digital imaging review
DESCRIPTION
Digital Imaging Review. RT 255. Display Workstations. Conventional film/screen radiography uses large multiviewer lightboxes. With early PACS, radiologists thought that they needed 4-6 monitors. Now, the number of monitors has dropped to an average of 2. - PowerPoint PPT PresentationTRANSCRIPT
RT 255
Digital Imaging Review
Display Workstationsbull Conventional filmscreen
radiography uses large multiviewer lightboxes
bull With early PACS radiologists thought that they needed 4-6 monitors
bull Now the number of monitors has dropped to an average of 2
bull Development of viewing software and better hardware
CRTbull The CRT is the most popular monitor on the market
bull It consists of a cathode and anode within a vacuum tube
bull Cathode boils off a cloud of electrons and then a potential difference is placed on the tube
bull A stream of electrons is sent across to the anode which in the case of the monitor is a sheet of glass coated with a phosphor layer
MONITORSDisplay Workstationsbull Early PACS reading rooms required
supplemental air-conditioning to offset the heat from multiple CRTs
bull Resolution and orientation of the monitor is also a factor in determining which type of monitor is to be used
bull Most cross-sectional imaging is read on a 1K square monitor
bull Most computed radiography (CR) and digital radiography (DR) images are read on at least a
2K portrait monitor
LCD
bull 13 megapixels bull to 5 megapixels bull mammography imaging =bull at least 5 megapixel resolution is
required
bull Rads VIEWERbull 4K or higher
Physician Review Stations Monitorsbull Step-down model of the radiologistrsquos reading
station (lower res)bull Some functions reducedbull One of the most important features bull is ability to view current and previous reports
with imagesbull Many vendors are integrating bull the RIS functions bull with PACS software
Technologist QC Stationsbull review images after acquisition
but before sending them to the radiologist
bull May be used to improve or adjust image-quality characteristics
bull May be used to verify patient demographic information
bull Placed between the CR and DR acquisition modalities as a pass-through to ensure that the images have met the departmental quality standard
Technologist QC Stationbull Generally has a 1K monitorbull Does not have the resolution capabilities of the
radiologistrsquos reading stationbull Care required of technologist when manipulating
images not to change the appearance too much from original acquired image
Technologist workstation monitors are used in brightly lighted areas So monitor luminance the brightness of a monitor display is an important consideration Also the monitor must allow a technologist to visualize enough detail to discern motion and that the recorded lines are sharp and visible
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Display Workstationsbull Conventional filmscreen
radiography uses large multiviewer lightboxes
bull With early PACS radiologists thought that they needed 4-6 monitors
bull Now the number of monitors has dropped to an average of 2
bull Development of viewing software and better hardware
CRTbull The CRT is the most popular monitor on the market
bull It consists of a cathode and anode within a vacuum tube
bull Cathode boils off a cloud of electrons and then a potential difference is placed on the tube
bull A stream of electrons is sent across to the anode which in the case of the monitor is a sheet of glass coated with a phosphor layer
MONITORSDisplay Workstationsbull Early PACS reading rooms required
supplemental air-conditioning to offset the heat from multiple CRTs
bull Resolution and orientation of the monitor is also a factor in determining which type of monitor is to be used
bull Most cross-sectional imaging is read on a 1K square monitor
bull Most computed radiography (CR) and digital radiography (DR) images are read on at least a
2K portrait monitor
LCD
bull 13 megapixels bull to 5 megapixels bull mammography imaging =bull at least 5 megapixel resolution is
required
bull Rads VIEWERbull 4K or higher
Physician Review Stations Monitorsbull Step-down model of the radiologistrsquos reading
station (lower res)bull Some functions reducedbull One of the most important features bull is ability to view current and previous reports
with imagesbull Many vendors are integrating bull the RIS functions bull with PACS software
Technologist QC Stationsbull review images after acquisition
but before sending them to the radiologist
bull May be used to improve or adjust image-quality characteristics
bull May be used to verify patient demographic information
bull Placed between the CR and DR acquisition modalities as a pass-through to ensure that the images have met the departmental quality standard
Technologist QC Stationbull Generally has a 1K monitorbull Does not have the resolution capabilities of the
radiologistrsquos reading stationbull Care required of technologist when manipulating
images not to change the appearance too much from original acquired image
Technologist workstation monitors are used in brightly lighted areas So monitor luminance the brightness of a monitor display is an important consideration Also the monitor must allow a technologist to visualize enough detail to discern motion and that the recorded lines are sharp and visible
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
CRTbull The CRT is the most popular monitor on the market
bull It consists of a cathode and anode within a vacuum tube
bull Cathode boils off a cloud of electrons and then a potential difference is placed on the tube
bull A stream of electrons is sent across to the anode which in the case of the monitor is a sheet of glass coated with a phosphor layer
MONITORSDisplay Workstationsbull Early PACS reading rooms required
supplemental air-conditioning to offset the heat from multiple CRTs
bull Resolution and orientation of the monitor is also a factor in determining which type of monitor is to be used
bull Most cross-sectional imaging is read on a 1K square monitor
bull Most computed radiography (CR) and digital radiography (DR) images are read on at least a
2K portrait monitor
LCD
bull 13 megapixels bull to 5 megapixels bull mammography imaging =bull at least 5 megapixel resolution is
required
bull Rads VIEWERbull 4K or higher
Physician Review Stations Monitorsbull Step-down model of the radiologistrsquos reading
station (lower res)bull Some functions reducedbull One of the most important features bull is ability to view current and previous reports
with imagesbull Many vendors are integrating bull the RIS functions bull with PACS software
Technologist QC Stationsbull review images after acquisition
but before sending them to the radiologist
bull May be used to improve or adjust image-quality characteristics
bull May be used to verify patient demographic information
bull Placed between the CR and DR acquisition modalities as a pass-through to ensure that the images have met the departmental quality standard
Technologist QC Stationbull Generally has a 1K monitorbull Does not have the resolution capabilities of the
radiologistrsquos reading stationbull Care required of technologist when manipulating
images not to change the appearance too much from original acquired image
Technologist workstation monitors are used in brightly lighted areas So monitor luminance the brightness of a monitor display is an important consideration Also the monitor must allow a technologist to visualize enough detail to discern motion and that the recorded lines are sharp and visible
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
MONITORSDisplay Workstationsbull Early PACS reading rooms required
supplemental air-conditioning to offset the heat from multiple CRTs
bull Resolution and orientation of the monitor is also a factor in determining which type of monitor is to be used
bull Most cross-sectional imaging is read on a 1K square monitor
bull Most computed radiography (CR) and digital radiography (DR) images are read on at least a
2K portrait monitor
LCD
bull 13 megapixels bull to 5 megapixels bull mammography imaging =bull at least 5 megapixel resolution is
required
bull Rads VIEWERbull 4K or higher
Physician Review Stations Monitorsbull Step-down model of the radiologistrsquos reading
station (lower res)bull Some functions reducedbull One of the most important features bull is ability to view current and previous reports
with imagesbull Many vendors are integrating bull the RIS functions bull with PACS software
Technologist QC Stationsbull review images after acquisition
but before sending them to the radiologist
bull May be used to improve or adjust image-quality characteristics
bull May be used to verify patient demographic information
bull Placed between the CR and DR acquisition modalities as a pass-through to ensure that the images have met the departmental quality standard
Technologist QC Stationbull Generally has a 1K monitorbull Does not have the resolution capabilities of the
radiologistrsquos reading stationbull Care required of technologist when manipulating
images not to change the appearance too much from original acquired image
Technologist workstation monitors are used in brightly lighted areas So monitor luminance the brightness of a monitor display is an important consideration Also the monitor must allow a technologist to visualize enough detail to discern motion and that the recorded lines are sharp and visible
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
LCD
bull 13 megapixels bull to 5 megapixels bull mammography imaging =bull at least 5 megapixel resolution is
required
bull Rads VIEWERbull 4K or higher
Physician Review Stations Monitorsbull Step-down model of the radiologistrsquos reading
station (lower res)bull Some functions reducedbull One of the most important features bull is ability to view current and previous reports
with imagesbull Many vendors are integrating bull the RIS functions bull with PACS software
Technologist QC Stationsbull review images after acquisition
but before sending them to the radiologist
bull May be used to improve or adjust image-quality characteristics
bull May be used to verify patient demographic information
bull Placed between the CR and DR acquisition modalities as a pass-through to ensure that the images have met the departmental quality standard
Technologist QC Stationbull Generally has a 1K monitorbull Does not have the resolution capabilities of the
radiologistrsquos reading stationbull Care required of technologist when manipulating
images not to change the appearance too much from original acquired image
Technologist workstation monitors are used in brightly lighted areas So monitor luminance the brightness of a monitor display is an important consideration Also the monitor must allow a technologist to visualize enough detail to discern motion and that the recorded lines are sharp and visible
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull Rads VIEWERbull 4K or higher
Physician Review Stations Monitorsbull Step-down model of the radiologistrsquos reading
station (lower res)bull Some functions reducedbull One of the most important features bull is ability to view current and previous reports
with imagesbull Many vendors are integrating bull the RIS functions bull with PACS software
Technologist QC Stationsbull review images after acquisition
but before sending them to the radiologist
bull May be used to improve or adjust image-quality characteristics
bull May be used to verify patient demographic information
bull Placed between the CR and DR acquisition modalities as a pass-through to ensure that the images have met the departmental quality standard
Technologist QC Stationbull Generally has a 1K monitorbull Does not have the resolution capabilities of the
radiologistrsquos reading stationbull Care required of technologist when manipulating
images not to change the appearance too much from original acquired image
Technologist workstation monitors are used in brightly lighted areas So monitor luminance the brightness of a monitor display is an important consideration Also the monitor must allow a technologist to visualize enough detail to discern motion and that the recorded lines are sharp and visible
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Physician Review Stations Monitorsbull Step-down model of the radiologistrsquos reading
station (lower res)bull Some functions reducedbull One of the most important features bull is ability to view current and previous reports
with imagesbull Many vendors are integrating bull the RIS functions bull with PACS software
Technologist QC Stationsbull review images after acquisition
but before sending them to the radiologist
bull May be used to improve or adjust image-quality characteristics
bull May be used to verify patient demographic information
bull Placed between the CR and DR acquisition modalities as a pass-through to ensure that the images have met the departmental quality standard
Technologist QC Stationbull Generally has a 1K monitorbull Does not have the resolution capabilities of the
radiologistrsquos reading stationbull Care required of technologist when manipulating
images not to change the appearance too much from original acquired image
Technologist workstation monitors are used in brightly lighted areas So monitor luminance the brightness of a monitor display is an important consideration Also the monitor must allow a technologist to visualize enough detail to discern motion and that the recorded lines are sharp and visible
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Technologist QC Stationsbull review images after acquisition
but before sending them to the radiologist
bull May be used to improve or adjust image-quality characteristics
bull May be used to verify patient demographic information
bull Placed between the CR and DR acquisition modalities as a pass-through to ensure that the images have met the departmental quality standard
Technologist QC Stationbull Generally has a 1K monitorbull Does not have the resolution capabilities of the
radiologistrsquos reading stationbull Care required of technologist when manipulating
images not to change the appearance too much from original acquired image
Technologist workstation monitors are used in brightly lighted areas So monitor luminance the brightness of a monitor display is an important consideration Also the monitor must allow a technologist to visualize enough detail to discern motion and that the recorded lines are sharp and visible
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Technologist QC Stationbull Generally has a 1K monitorbull Does not have the resolution capabilities of the
radiologistrsquos reading stationbull Care required of technologist when manipulating
images not to change the appearance too much from original acquired image
Technologist workstation monitors are used in brightly lighted areas So monitor luminance the brightness of a monitor display is an important consideration Also the monitor must allow a technologist to visualize enough detail to discern motion and that the recorded lines are sharp and visible
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Technologist workstation monitors are used in brightly lighted areas So monitor luminance the brightness of a monitor display is an important consideration Also the monitor must allow a technologist to visualize enough detail to discern motion and that the recorded lines are sharp and visible
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
The File Room Workstationbull Workstation may be used to bull look up exams for a physician bull or to print copies of images bull for the patient to take to an bull outside physicianbull Many hospitals are moving away from
printing films because of the costbull Hospitals are moving toward burning
compact disks (CDs) with the patientrsquos images
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Name the 3 types of monitors
bull Two major types of monitors with a third type gaining acceptance
bull CRTbull LCDbull Plasma screen
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Image Display= MONITORSbull viewing conditions
ndash (ieluminanceambient lighting)bull spatial resolution bull contrast resolutiondynamic range bull DICOM gray scale function bull window level and width function
ARRT DEFINITIONS
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
viewing conditions luminanceambient lighting
bull How does this affect viewing imagesbull Surrounding light impacted what was seen on
image ndash now With different monitors
bull LCD gives more lightbull LCD can be used in areas with a high amount of ambient light
ldquodark roomsrdquo not necessary
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
WINDOW LEVEL WIDTHWhich one controls
Denisty (brightness) Contrast
What else control these in DIGITAL IMAGING
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull The ability to window is a valuable feature of all digital images
bull Windowing is the process of selecting some segment of the total pixel value range (the wide dynamic range of the receptors) and then displaying the pixel values within that segment over the full brightness (shades of gray) range from white to black
bull Important pointContrast will be visible only for the pixel values that are within the selected window All pixel values that are either below or above the window will be all white or all black and display no contrast
bull The person controlling the display can adjust both the center and the width of the window The combination of these two parameters determine the range of pixel values that will be displayed with contrast in the image
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Enhanced Visualization Image Processing
bull Takes image diagnostic quality to a new levelbull Increases latitude while preserving contrastbull Process decreases windowing and levelingbull Virtually eliminates detail loss in dense tissues
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Nyquist frequency Reviewbull The highest spatial frequency that can be
recorded by a digital detector bull is determined by the ________________ bull The Nyquist frequency is half the number
of pixelsmm
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
10 PIXEL DENSITYWHAT IS THE NYQUIST FREQUENCY=
A digital system with a pixel density of 10 pixelsmm would have a Nyquist frequency of 5 line pairmm
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Sampling Frequency Define helliphellip
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Sampling Frequency
bull The sampling frequency is the rate atbull which the laser extracts the image databull from the plate
bull What other term does this relate to
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Nyquist Frequency
bull The Nyquist Frequency will be frac12 of the sampling frequencybull A plate that is scanned using a sampling
frequency of 10 pixels per millimeter would not be able to demonstrate more than 5 line pairs per millimeter based upon the Nyquist Frequency
bull The Nyquist Frequency allows thebull determination of the spatial resolution forbull a given sampling frequency
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull In the typical digital radiographic system a variety of LUTs are installed
bull The appropriate LUT is then automatically selected to give the desired contrast characteristics to match the type of procedure (chest extremity etc) that is designated by the operator
LUT
a histogram of the luminance values derived during image acquisition used as a reference to evaluate the raw information and correct the luminance values a mapping function in which all pixels are changed to a new gray value
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
LOOK UP TABLE (LUT)
Linear LUT
Black Shirt
Facial Tones
Black Saturation
White Saturation
No Detail in Black Areas High Contrast Only Detail in White Areas can be seen
No Detail in White Areas Low Contrast Only Detail in Black Areas can be seen
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
image signal (exposure related) Exposure Indicators
bull The amount of light given off by the imaging plate is a result of the radiation exposure that the plate has received
bull The light is converted into a signal that is used to calculate the exposure indicator number which is a different number from one vendor to another
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Digital artifacts
bull Grid Lines Appear as grid cutoff bull Moire (Aliasing)
ndash wavy artifact occurs because the grid lines and the scanning laser are parallel
ndash When the spatial frequency is greater than the Nyquist frequency
bull Maintenance (eg detector fog) When errors occur in equipment performance corrective action must occur These corrections will generally be done by service personnel employed by the vendor
bull non-uniformity erasure - blub problems
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
How else can Morie OCCUR
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
quantum mottleARRT definitions
failure of an imaging system to record densities usually caused by a lack of x-ray photons
ldquoPHOTON STARVEDrdquo
KVP amp MAS HOW IS THIS AFFECTED IN DR CR
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
PREPROCESSING ARTIFACTS
- dead detector elements- dead columns or rows- nonuniform response- heel effect (fixed systems)- light guide variations- ghosting
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Image Receptors
digital image characteristicsndash spatial resolutionndash sampling frequencyndash DEL (detector element size)ndash receptor size and matrix sizendash image signal (exposure related)ndash quantum mottlendash SNR (signal to noise ratio) orndash CNR (contrast to noise ratio)
ARRT definitions
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Image Acquisition and Readout
bull PSP (photo-stimulable phosphor)bull flat panel detectors
ndash (direct and indirect)
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
CR Imaging Platebull Constructionbull Image recorded on a thin sheet of plastic known
as the imaging plate - PSPbull Consists of several layersbull Phosphor
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Imaging Platebull Phosphor
bull BARIUM FLUORO bull HALIDE WITH bull A EUROPIUM BASE
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull Two types of digital radiographybull Indirect capture DR
bull Machine absorbs x-rays and converts them to light
bull CCD or thin-film transistor (TFT) converts light to electric signals
bull Computer processes electric signalsbull Images are viewed on computer
monitor
Digital Radiography
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull Direct capture DRbull Photoconductor
absorbs x-raysbull TFT collects signalbull Electrical signal is
sent to computer for processing
bull Image is viewed on computer screen
Digital Radiography
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Image Acquisition and Readout
flat panel detectorsPhosphors
ndash direct = Am SELENIUM
ndash indirect = Am SILICON
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull CR PSL light guide PMTPDbull Indirect CsIGOS contact layer PDTFT
arraybull Direct a-Se none TFT
arraybull CCDCMOS CsGOS lensfiber
CCDCMOS
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
CMOS
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
CMOS
bull Complimentary metal-oxide semi-conductor (CMOS) ndash A photographic detector
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull CCD and CMOS systems ndash both use a scintillator These systems are camera-like
bull they both use lenses to focus the light onto a detector
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull Digital Systemsbull electronic collimationbull grayscale rendition or look-up table (LUT)bull edge enhancement
ndash noise suppressionbull contrast enhancementbull system malfunctions (eg ghost image
banding erasure dead pixels readout problems printer distortion)
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Image Data Recognitionand Preprocessing shutter
bull Agfa uses the term collimation Kodak uses the term segmentation and Fuji uses the phrase ldquoexposure data recognitionrdquo
bull All systems use a region of interest to define the area where the part to be examined is recognized and the exposure outside the region of interest is subtracted
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull Excessive exposure to receptor without rescaling
bull Excessive exposure to receptor with rescaling
bull So in essence rescaling provided an acceptable image despite an excess level of exposure to the receptor
What about the dose to the patient
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Rescalingbull image pixel values to appear appropriate
display properly can lead to overexposing a patient
bull The visual cue to the technologist that overexposure has occurred isnrsquot present
bull With an analog system a technologist would have seen the image on the left as it came out of the processor and used the excessive density of the image as a visual cue to repeat the image
bull Rescaling forces a technologist to look elsewhere for signs that a proper exposure was used to produce an image
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Dose creep
bull refers to the potential to gradually increase patient exposure over time
bull However a technologist lacks visual feedback that additional radiation is being used to produce the images
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
DAPbull The dose area product (DAP) meter is a device that may
be interlinked with the x-ray unit to determine the actual patient entrance skin exposure dose with accurately calibrated equipment Currently no standards are established for using a dose area product meter
These two radiographs show the difference in entrance skin exposure measured by the DAP meter The area with a smaller exposure field size carries a lower exposure without reducing image quality
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Exposure Latitude
bull The analog receptor exposure latitude ranges from approximately
bull 30 underexposedbull to 50 overexposed relative tobull the ldquoidealrdquo exposure level
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Exposure Latitude
The digital image receptorbull exposure latitude ranges frombull approximately bull 50 underexposedbull to 100 over exposurebull relative to the ldquoidealrdquo exposure level
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
NoteIt is important to note that just because abull digital imaging system has the capacity tobull produce an image from gross underexposurebull or gross overexposure it does not equate tobull greater exposure latitude bull The reason the system is capable of producing
an image when significant exposure errors occur is through a process called automatic rescaling
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull In a digital system underexposure ofbull 50 or greater will result in a mottledbull image
bull 1048737 In a digital system overexposurebull greater than 200 of the ideal will resultbull in loss of image contrast
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Image EvaluationBrightness and Contrast in Images
bull Exposure Field Recognition Errorbull Gross Overexposurebull Excessive Scatter Striking the Receptorbull Excessive Fog on the Receptorbull Grid Cutoff bull Intra-Field or Off-Focus Radiationbull Wrong Menu Selection
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
EDR
bull Exposure Data Recognitionbull When laser scans it is looking for area of
plate that has exposurebull Some read from center out and look for
two sides of collimationbull Works best when image centered
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
S 12361 lat CXR
S 8357
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Exposure Numbers
bull The exposure numbers can only be used if all other parameters are correctndash Centering to platendash Collimation
bull Position over AEC look at mAs readout to determine if poor positioning caused light or dark image
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Same technique different centering and collimation
S 592 S 664
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
ARRT SPECS - DIGITAL
bull PACSbull HIS (hospital information system) - work
listbull RIS (radiology information system)bull DICOMbull Workflow (inappropriate documentation
lost images mismatched images corrupt data)
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
PACSbull Image is stored on a computer retrieval and
viewing system for digital imaging examinationsbull The PACS software provides ldquotoolsrdquo that enable
a PACS operator to manipulate images bull The basic image manipulations possible are
magnification and minification of an image altering image brightness and contrast and annotating the image using text symbols lines and arrows
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Picture Archival andCommunication Systems
bull Networked group of computers servers and archives to store digital images
bull Can accept any image that is in DICOM format
bull Serves as the file room reading room duplicator and courier
bull Provides image access to multiple users at the same time on-demand images electronic annotations of images and specialty image processing
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
HIS ndash RIS INTERFACE
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
RIS Data Storage
bull Less ERRORS
bull A radiology information system or RIS is a data system for patient-related functions in the radiology department Examples of functionality a RIS provides within a radiology department include (but are not limited to)
bull scheduling bull appointments bull collecting and displaying orders for radiologic
examinationsbull storing and displaying patient data bull tracking patients bull providing patient and order data to a PACS storing and
distributing radiology reports providing billing services and providing a database to track and project trends
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
HIS
bull A hospital information system or HIS is a paper andor data system that manages the administrative financial and clinical information necessary to operate a hospital or health care system
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Health Level 7 (HL7)
bull HL7 are the software standards established for exchanging electronic information in health care PACS is mainly concerned with images and data associated with images whereas HL7 sets standards for transmitting text-based information throughout a medical center
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Cassette-based systems
PSP plates
bull Turbid phosphors
bull Structured phosphors
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull Turbid Phosphor ndash A phosphor layer with a random distribution of phosphor crystals within the active layer
bull Structured (needle) phosphor ndash A phosphor layer with columnar phosphor crystals within the active layer Resembles needles lined up on end and packed together
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Exposure indexbull Cassette basedndash represents exposure level to platebull a Vendor specific valuesbull 1) Sensitivity ldquoSrdquo (Fuji Philips Konica) inversely related
to exposure- 200 S =1mR to the plate ndash optimal range 250-300 for trunk 75-125 for extremities
bull 2) Exposure Index (EI)- (Kodak) ndash directly related to exposure has a logarithmic component (change of 300 in EI = factor of 2 ie 1800 is exposed twice as much as 1500) optimal range 1800-1900
bull 3) Log Mean (LgM) - (Agfa) ndash directly related to exposure has a logarithmic component (change of 03 in LgM = factor of 2 ie 23 is exposed twice as much as 20) optimal range 19-21
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
bull MTF
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
MODULATION TRANSFER FUNCTION - MTF
bull A measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution
bull Every image can be described in terms of the amount of energy for each of its spatial frequency components
bull MTF often is regarded as the ideal expression of the image quality provided by a detector
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Exposure myths associated with digital systems
1 mAs ndash myth digital is mAs driven Truth digital is exposure driven The digitaldetector is unable to discriminate whether theexposure change was mAs or kVp Theonly thing that matters is exposure to pixels2 kVp ndash myth digital is kVp driven Truth see above3 Collimation ndash myth you cannot collimate Truth you can and should collimateInappropriate collimation will cause a histogram
analysis error
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Exposure myths associated with digital systems
4 Grid ndash myth cannot use grids and donrsquot need them
Truth digital systems are sensitive to scatter just like film in fact they are more sensitive Appropriate grid useis even more important A grid should be used when the remnant beam is more than 50 scatter chest larger than 24cm and anything else larger than 12cm
5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant
TruthGeometric rules of recorded detail and distortion are unchanged from film to digital
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Exposure myths associated with digital systems
7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truthdigital systems are more sensitive to both
8 Myth fluorescent lights fog PSP plates Truth that is not true
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-
Next
bull ODIA - Summer Reviewbull Prep for Registry Exam
- Digital Imaging Review
- Display Workstations
- CRT
- MONITORSDisplay Workstations
- LCD
- Slide 6
- Physician Review Stations Monitors
- Technologist QC Stations
- Technologist QC Station
- Slide 10
- The File Room Workstation
- Name the 3 types of monitors
- Image Display= MONITORS
- viewing conditions luminanceambient lighting
- WINDOW LEVEL WIDTH Which one controls Denisty (brightness)
- Slide 16
- Enhanced Visualization Image Processing
- Nyquist frequency Review
- Slide 19
- Slide 20
- Sampling Frequency Define helliphellip
- Sampling Frequency
- Nyquist Frequency
- Slide 24
- LOOK UP TABLE (LUT)
- Slide 26
- Image Receptors
- image signal (exposure related) Exposure Indicators
- Digital artifacts
- How else can Morie OCCUR
- quantum mottle
- PREPROCESSING ARTIFACTS
- Slide 33
- Slide 34
- Image Receptors (2)
- Image Acquisition and Readout
- CR Imaging Plate
- Imaging Plate
- Digital Radiography
- Digital Radiography (2)
- Image Acquisition and Readout (2)
- Slide 42
- CMOS
- CMOS (2)
- Slide 45
- Slide 46
- Image Data Recognition and Preprocessing shutter
- Rescaling
- Dose creep
- DAP
- Exposure Latitude
- Exposure Latitude (2)
- Note
- Slide 55
- Image Evaluation Brightness and Contrast in Images
- EDR
- Slide 58
- Slide 59
- Slide 60
- Exposure Numbers
- Same technique different centering and collimation
- ARRT SPECS - DIGITAL
- PACS
- Picture Archival and Communication Systems
- HIS ndash RIS INTERFACE
- RIS Data Storage
- HIS
- Health Level 7 (HL7)
- Slide 70
- Slide 71
- Slide 72
- Exposure index
- Slide 74
- MODULATION TRANSFER FUNCTION - MTF
- Exposure myths associated with digital systems
- Exposure myths associated with digital systems (2)
- Exposure myths associated with digital systems (3)
- Next
-