Computed Radiography

Objectives

Historical perspectives of computerized imaging

SF vs CR vs DDR imaging Basics of CR image capture CR imaging equipment Advantages of CR imaging Radiation Protection

Digital Imaging

bull Image acquisition that produces an electronic image that can be viewed and manipulated on a computer

bull Analog-to-digital converters

Development of Digital Imaging

bull The second major milestone in medical imaging the invention of CT

bull Began the coupling of the computers and imaging

bull Godfrey Hounsfield in the 1970rsquos

First-generation CT unit dedicated head scanner

(Photograph taken at Roentgen Museum Lennep Germany)

Digital Imaging Techniques

Are used inComputed TomographyMagnetic Resonance ImagingDiagnostic UltrasoundComputerized RadiographyDigital RadiographyDigital Fluoroscopy

CR amp DR imaging

Was limited until sufficient computer technology became available to process the large quantities of data generated

Clinical use began in the 1980rsquos (CR)

1990rsquos (DDR)

Methods to Digitize an Imagebull 1 Film Digitizer - Teleradiography system

(PACS DICOM)

bull 2 Video Camera (vidicon or plumbicon)

bull 3 Computed Radiography

bull 4 Direct Radiography

Computed Radiography Terms

PSL = photostimulable luminescence PSP = photostimulable phosphor SPS = storage phosphor screen IP = imaging plate SP = storage phosphor PMT = photomultiplier tube PD = photodiode SF = screen-film

Computed Radiography

Fundamentals of

Computerized Radiography

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Objectives

Historical perspectives of computerized imaging

SF vs CR vs DDR imaging Basics of CR image capture CR imaging equipment Advantages of CR imaging Radiation Protection

Digital Imaging

bull Image acquisition that produces an electronic image that can be viewed and manipulated on a computer

bull Analog-to-digital converters

Development of Digital Imaging

bull The second major milestone in medical imaging the invention of CT

bull Began the coupling of the computers and imaging

bull Godfrey Hounsfield in the 1970rsquos

First-generation CT unit dedicated head scanner

(Photograph taken at Roentgen Museum Lennep Germany)

Digital Imaging Techniques

Are used inComputed TomographyMagnetic Resonance ImagingDiagnostic UltrasoundComputerized RadiographyDigital RadiographyDigital Fluoroscopy

CR amp DR imaging

Was limited until sufficient computer technology became available to process the large quantities of data generated

Clinical use began in the 1980rsquos (CR)

1990rsquos (DDR)

Methods to Digitize an Imagebull 1 Film Digitizer - Teleradiography system

(PACS DICOM)

bull 2 Video Camera (vidicon or plumbicon)

bull 3 Computed Radiography

bull 4 Direct Radiography

Computed Radiography Terms

PSL = photostimulable luminescence PSP = photostimulable phosphor SPS = storage phosphor screen IP = imaging plate SP = storage phosphor PMT = photomultiplier tube PD = photodiode SF = screen-film

Computed Radiography

Fundamentals of

Computerized Radiography

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Digital Imaging

bull Image acquisition that produces an electronic image that can be viewed and manipulated on a computer

bull Analog-to-digital converters

Development of Digital Imaging

bull The second major milestone in medical imaging the invention of CT

bull Began the coupling of the computers and imaging

bull Godfrey Hounsfield in the 1970rsquos

First-generation CT unit dedicated head scanner

(Photograph taken at Roentgen Museum Lennep Germany)

Digital Imaging Techniques

Are used inComputed TomographyMagnetic Resonance ImagingDiagnostic UltrasoundComputerized RadiographyDigital RadiographyDigital Fluoroscopy

CR amp DR imaging

Was limited until sufficient computer technology became available to process the large quantities of data generated

Clinical use began in the 1980rsquos (CR)

1990rsquos (DDR)

Methods to Digitize an Imagebull 1 Film Digitizer - Teleradiography system

(PACS DICOM)

bull 2 Video Camera (vidicon or plumbicon)

bull 3 Computed Radiography

bull 4 Direct Radiography

Computed Radiography Terms

PSL = photostimulable luminescence PSP = photostimulable phosphor SPS = storage phosphor screen IP = imaging plate SP = storage phosphor PMT = photomultiplier tube PD = photodiode SF = screen-film

Computed Radiography

Fundamentals of

Computerized Radiography

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Development of Digital Imaging

bull The second major milestone in medical imaging the invention of CT

bull Began the coupling of the computers and imaging

bull Godfrey Hounsfield in the 1970rsquos

First-generation CT unit dedicated head scanner

(Photograph taken at Roentgen Museum Lennep Germany)

Digital Imaging Techniques

Are used inComputed TomographyMagnetic Resonance ImagingDiagnostic UltrasoundComputerized RadiographyDigital RadiographyDigital Fluoroscopy

CR amp DR imaging

Was limited until sufficient computer technology became available to process the large quantities of data generated

Clinical use began in the 1980rsquos (CR)

1990rsquos (DDR)

Methods to Digitize an Imagebull 1 Film Digitizer - Teleradiography system

(PACS DICOM)

bull 2 Video Camera (vidicon or plumbicon)

bull 3 Computed Radiography

bull 4 Direct Radiography

Computed Radiography Terms

PSL = photostimulable luminescence PSP = photostimulable phosphor SPS = storage phosphor screen IP = imaging plate SP = storage phosphor PMT = photomultiplier tube PD = photodiode SF = screen-film

Computed Radiography

Fundamentals of

Computerized Radiography

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

First-generation CT unit dedicated head scanner

(Photograph taken at Roentgen Museum Lennep Germany)

Digital Imaging Techniques

Are used inComputed TomographyMagnetic Resonance ImagingDiagnostic UltrasoundComputerized RadiographyDigital RadiographyDigital Fluoroscopy

CR amp DR imaging

Was limited until sufficient computer technology became available to process the large quantities of data generated

Clinical use began in the 1980rsquos (CR)

1990rsquos (DDR)

Methods to Digitize an Imagebull 1 Film Digitizer - Teleradiography system

(PACS DICOM)

bull 2 Video Camera (vidicon or plumbicon)

bull 3 Computed Radiography

bull 4 Direct Radiography

Computed Radiography Terms

PSL = photostimulable luminescence PSP = photostimulable phosphor SPS = storage phosphor screen IP = imaging plate SP = storage phosphor PMT = photomultiplier tube PD = photodiode SF = screen-film

Computed Radiography

Fundamentals of

Computerized Radiography

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Digital Imaging Techniques

Are used inComputed TomographyMagnetic Resonance ImagingDiagnostic UltrasoundComputerized RadiographyDigital RadiographyDigital Fluoroscopy

CR amp DR imaging

Was limited until sufficient computer technology became available to process the large quantities of data generated

Clinical use began in the 1980rsquos (CR)

1990rsquos (DDR)

Methods to Digitize an Imagebull 1 Film Digitizer - Teleradiography system

(PACS DICOM)

bull 2 Video Camera (vidicon or plumbicon)

bull 3 Computed Radiography

bull 4 Direct Radiography

Computed Radiography Terms

PSL = photostimulable luminescence PSP = photostimulable phosphor SPS = storage phosphor screen IP = imaging plate SP = storage phosphor PMT = photomultiplier tube PD = photodiode SF = screen-film

Computed Radiography

Fundamentals of

Computerized Radiography

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

CR amp DR imaging

Was limited until sufficient computer technology became available to process the large quantities of data generated

Clinical use began in the 1980rsquos (CR)

1990rsquos (DDR)

Methods to Digitize an Imagebull 1 Film Digitizer - Teleradiography system

(PACS DICOM)

bull 2 Video Camera (vidicon or plumbicon)

bull 3 Computed Radiography

bull 4 Direct Radiography

Computed Radiography Terms

PSL = photostimulable luminescence PSP = photostimulable phosphor SPS = storage phosphor screen IP = imaging plate SP = storage phosphor PMT = photomultiplier tube PD = photodiode SF = screen-film

Computed Radiography

Fundamentals of

Computerized Radiography

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Methods to Digitize an Imagebull 1 Film Digitizer - Teleradiography system

(PACS DICOM)

bull 2 Video Camera (vidicon or plumbicon)

bull 3 Computed Radiography

bull 4 Direct Radiography

Computed Radiography Terms

PSL = photostimulable luminescence PSP = photostimulable phosphor SPS = storage phosphor screen IP = imaging plate SP = storage phosphor PMT = photomultiplier tube PD = photodiode SF = screen-film

Computed Radiography

Fundamentals of

Computerized Radiography

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Computed Radiography Terms

PSL = photostimulable luminescence PSP = photostimulable phosphor SPS = storage phosphor screen IP = imaging plate SP = storage phosphor PMT = photomultiplier tube PD = photodiode SF = screen-film

Computed Radiography

Fundamentals of

Computerized Radiography

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Computed Radiography

Fundamentals of

Computerized Radiography

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

CR IR

Cassette-based digital radiography

In SF the intensifying screens contain phosphor that emits light in response to x-ray interaction

In CR the response to x-ray interaction is trapped photon energy (e-) on the PSP plate

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Conventional radiography latent image formation

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

CR latent image formation

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

What Is Digital ImagingDigital imaging is the acquisition of

images to a computer rather than directly to film

15

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

IMAGE CREATION

SAME RADIOGRAPHY EQUIPMENT USED

THE DIFFERENCE IS HOW IT IS CAPTURED

STORED VIEWED And POST -PROCESSED

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

General Overview CR

PSP cassette exposed by conventional x-ray equipment

Latent image generated as a matrix of trapped electrons in the PSP plate

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

CR BASICS

bull Eliminates the need for film as a recording storage amp viewing medium

bull PSP Plate ndash receiverbull Archive Manager ndash storagebull Monitor - Viewing

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Digital

Radiography

DirectCapture

IndirectCapture

Direct-to-DigitalRadiography

(DDR)-Selenium

ComputedRadiography

(CR) - PSL

LaserScanningDigitizers

Direct-to-DigitalRadiographySilicon Scint

DDR CR

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

CR SYSTEM COMPONENTS

CASSETTES (phosphor plates) ID STATION IMAGE PREVIEW (QC)

STATION DIGITIZER VIEWING STATION

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

ID STATIONID STATION

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

CR Readers

AKA

CR Processors

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Fuji Agfa Kodak

Computed Radiographic Readers

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

CR ndash PSP plate

photostimulable phosphor (PSP) plate

Exit photons energizes the PSP plate

The energy is stored in traps on plate (latent image)

PLATE scanned in CR READER

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Imaging Plate (IP)

Contained in a cassette

Handled the same as SF cassettes

Processed more like daylight processor with no chemicals

IP has lead backing to reduce scatter

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Imaging Plate Construction

A thin sheet of plastic

IPrsquos have several layersA protective layer This is a very thin tough

clear plastic that protects the phosphor layer A phosphor or active layer This is a layer of

photostimulable phosphor that ldquotrapsrdquo electrons during exposure

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Active Layer - Crystals The materials that make up the PSP plate

are from the barium fluorohalide family

Barium fluorohalide chlorohalide or bromohalide crystals The most common crystal uses is barium fluorohalide with europium

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Acquiring the Image

The remnant beam interacts with electrons in the barium fluorohalide crystals

This interaction stimulates or gives energy to electrons in the crystals allowing them to enter the conductive layer

The Conductuve layer is where they are

trapped in an area of the crystal known as the color or phosphor center

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Acquiring the Image cont

This trapped signal will remain for hours even days although deterioration begins almost immediately IR should be processed as soon as possible

The trapped signal is never completely lost

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Imaging Plate Construction

A reflective layer This is a layer that sends light in a forward direction when released in the cassette reader This layer may be black to reduce the spread of stimulating light and the escape of emitted light Some detail is lost in this process

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Imaging Plate Construction Conductive layer This is a layer of material that

absorbs and reduces static electricity A color layer Newer plates may contain a color

layer located between the active layer and the support that absorbs the stimulating light but reflects emitted light

A support layer This is a semirigid material that gives the imaging sheet some strength

A backing layer This is a soft polymer that protects the back of the cassette

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Cross section of a PSP screen

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Needle PSP increase the absorption of x-rays and limit the spread of light emission

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

IP Design

Designed to optimize the intensity of light release (CE)

Enhance the absorption of x-rays (DQE)

Limit the spread of light emission for more detail

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Photostimulable Luminescence When the cassette is put into the reader the

imaging plate is extracted and scanned With a helium laser beam or in more recent

systems solid-state laser diodes This beam about 100μm wide with a wavelength

of 633 nm (or 670 to 690 nm for solid state) Scans the plate with red light in a raster pattern

and gives energy to the trapped electrons

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

X-ray interaction with a PSP screen

1

2

X-ray interactions with the screen phosphors causes an e- to excited

When e- return to groundstate visible light is emitted

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

CR Phosphor PlatesCR Phosphor Plates

ABSORPTION EMISSION

X-RAY

LIGHT

LASER STIMULATION

ELECTRONTRAP

ELECTRONTRAP

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

CR Reader ndash PSP plate

Stimulates the matrix of trapped E- by a RED OR ULTRAVIOLET laser light

Trapped E- energy is released in a form of VIOLETBLUE light

Violet light is captured by PMT ndash is amplified and converted into a digital signal

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Sequence of CR imaging

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

PMT

Beam deflector

LaserSource

Light channeling guide

Plate translation Sub-scan direction

Laser beam Scan direction

Output Signal

Reference detec tor

Beam splitter

Cylindrical m irrorf-thetalens

Amplifier

ADC

To imageprocessor

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

How CR works

Released light is captured by a PMT (photo

multiplier tube) An ultrasensitive photomultiplier tube or CCD (charged couple device)

PSP light is amplified by the PMT or CCD

This light is sent to the analog to digital converter (ADC) To convert light to binary

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

PMT (photomultiplier tube) The intensity (brightness) of the light ndash

correlates to the density on the image

So lots of light will correlate to what size number amp what color on the image

The digital numeric values are stored in matrix form called pixels for display on a cathode ray tube (CRT) or printed on film

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

ERASING THE SCREEN ~50 of trapped electrons released during ldquoreadrdquo After image is recorded Plate is erased with high intensity white light and

re-used Erasing should be done after every exposure or

at minimum every 24 hours to avoid ghosting on future images

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Basics of Digital Images

bull digital images are a (matrix) of pixel (picture element) values

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Pixels Digital images are made of discrete picture

elements arranged in a matrix The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Matrix = each cell corresponds to a specific location on the image

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Pixel

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Pixels

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Digital Images ndash Bit Depth

bull Pixel values can be any bit depth (values from 0 to 1023)

bull Bit depth = or gray shades available for image display

bull Image contrast can be manipulated to stretched or contracted to alter the displayed contrast

bull Typically use ldquowindow widthrdquo and ldquowindow levelrdquo to alter displayed contrast and brightness

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Digital - Grayscale

Bit depth Number of gray shades

available for display 8 bit 256 10 bit 1024 12 bit 4096 4 bit 16384

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Display Bit Depth1 bit 6 bit 8 bit

2 shades 64 shades 256 shades

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Computed Radiography As the plate is scanned ldquoreadrdquo data is collected

at a specific frequency = Sampling frequency

Spatial resolution determined by sampling frequency

With some systems the smaller IRrsquos have higher sampling frequencies amp more pixels per mm = more spatial resolution

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Signal Loss (reducing image quality) Signal-to-Noise Ratio

Principle source of noise on the image is scatter radiation

Scattering of emitted light off screen

The efficiency of the photomultiplier tubes (PMTs) and photodiodes (PDs)

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Improving Signal-to-Noise Ratio

Optical filter is used to prevent the longer-wavelength laser light affecting the image formation

Increasing exposure to IR Newer CR systems are better at reducing noise at lower exposure levels

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Technique Selections

What are some factors that technologist must take into consideration when selecting a technique

What regulates that technologists to select appropriate techniques in FS CR amp DR

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Screen Film

Self regulating system The receptor speed and film HampD curve defined

the proper exposure Achieving optimal OD guaranteed appropriate

exposure to the patient Over exposed = dark image Correct exposure = correct OD Under exposed = light image

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Characteristic curveof radiographic film

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Characteristic Curve

Sometimes called the HampD curve for Hurter and Driffield who first described the relationship

Describes the relationship between OD and exposure

Exposure changes near the toe or shoulder result in very little OD changes

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Screen Film Imaging = self regulating

2 mAsUnder exposed

6 mAsCorrect exposure

24 mAsOver exposed

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

CR imaging results in 10000 shades of gray

Fixed kVp exposures

mAs = 05S = 357

mAs = 10 S = 175

mAs = 20S = 86

mAs = 50S = 35

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

SF fundamental principle

Keep receptor exposure constant for given receptor response

The receptor exposure level (mR) depends on

Receptor ldquospeedrdquo 100 speed ~ 2 mR (to IR for appropriate OD)

200 speed ~1 mR 400 speed ~ 05 mR

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Speed Class

For CR imaging the speed is determined by the image quality required by the Radiologists or programmed by the service engineer Dependent on exposure to the PSP plate 200 RS = highest quality images Increasing RS will reduce contrast resolution and patient dose

S numbers Index numbers Sensitivity numbers Exposure index

Each imaging system is unique

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Dose Implications

Images nearly always look better at

higher exposures

FS system on average used a 400 RS combinationCR looks best at 200 RS If you were a manufacture how would you set up

your system for image quality vs ALARA

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

55 15 30

100 200 500

80 KVP

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Dose Implications Huge dynamic range means nearly impossible to

overexpose

Then the COMPUTER corrects majority of exposure errors

Therefore almost ANY technique can be used on the patient ndash

The computer will fix it

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

POST PROCESSING

Part Selection

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Workstation Menu

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

ALGORITHM ndash a set of mathematical values used to solve a problem or find an average

HISTOGRAM ndash a bar graph depicting the density distribution (in numerical values) of the imaging plate

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Wrong Algorithm

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Histogram showing pixel values in an image The pixel values in gray are on the horizontal with the total number for each on the vertical

DarkerLighter

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Histogram Analysis

A histogram is a plot of gray scale value vs the frequency of occurrence

pixels of the gray value in the image A graph that displays signal value x-axis related to amount of exposure y-axis displays number of pixels for each exposure Series of peaks and valleys Pattern varies for each body part

Statistical plots of the

frequency of occurrence of

each pixels value

Initial Image Processing

Automated exposure field edge detection

Eliminates signals outside collimation margins

If margin not detected extraneous data included in the histogram

EDR

Exposure Data Recognition When laser scans it is looking for area of

plate that has exposure Some read from center out and look for

two sides of collimation Works best when image centered

Exposure Indicators

Imaging plates get a signal from the exposure they receive

The value of the signal is calculated from the region identified as the anatomy of interest

The signal for the plate is an average of all signals given to the plate

Exposure Values

Each system has range of values for appropriate exposure for part

The range used by vendor is very broad Each facility should develop its own

exposure range taking into accountRadiologist preferenceALARA

S numbers Index numbers Sensitivity numbers Exposure index

The total signal is not a measure of the dose to the patient but indicates how much radiation was absorbed by the plate

A 1 mR exposure will giveFuji S 200KodakCarestream EI 2000Agfa 200 speed lgm reference value for site

EXPOSURE VALUES

Exposure indicatorPlates sensitive to 01 mR ndash 100 mR ldquoSrdquo number for Fuji

S number inverse to exposureS=2 (100 mR) S=200 (1 mR)

CarestreamKodak uses exposure index ndash direct relationship2000 (1 mR) 3000 (10 mR)

Using Exposure Numbers

Fuji if appropriate is 200 thenAt 400 too light double mAs for 200At 100 too dark half mAs for 200

Kodak if appropriate is 1800At 1500 too light double mAs for 1800At 2100 to dark half mAs for 1800

Exposure Numbers

The exposure numbers can only be used if all other parameters are correctCentering to plateCollimation

Position over AEC look at mAs readout to determine if poor positioning caused light or dark image

S 12361 lat CXRS 8357

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Initial Image Processing

Automated exposure field edge detection

Eliminates signals outside collimation margins

If margin not detected extraneous data included in the histogram

EDR

Exposure Data Recognition When laser scans it is looking for area of

plate that has exposure Some read from center out and look for

two sides of collimation Works best when image centered

Exposure Indicators

Imaging plates get a signal from the exposure they receive

The value of the signal is calculated from the region identified as the anatomy of interest

The signal for the plate is an average of all signals given to the plate

Exposure Values

Each system has range of values for appropriate exposure for part

The range used by vendor is very broad Each facility should develop its own

exposure range taking into accountRadiologist preferenceALARA

S numbers Index numbers Sensitivity numbers Exposure index

The total signal is not a measure of the dose to the patient but indicates how much radiation was absorbed by the plate

A 1 mR exposure will giveFuji S 200KodakCarestream EI 2000Agfa 200 speed lgm reference value for site

EXPOSURE VALUES

Exposure indicatorPlates sensitive to 01 mR ndash 100 mR ldquoSrdquo number for Fuji

S number inverse to exposureS=2 (100 mR) S=200 (1 mR)

CarestreamKodak uses exposure index ndash direct relationship2000 (1 mR) 3000 (10 mR)

Using Exposure Numbers

Fuji if appropriate is 200 thenAt 400 too light double mAs for 200At 100 too dark half mAs for 200

Kodak if appropriate is 1800At 1500 too light double mAs for 1800At 2100 to dark half mAs for 1800

Exposure Numbers

The exposure numbers can only be used if all other parameters are correctCentering to plateCollimation

Position over AEC look at mAs readout to determine if poor positioning caused light or dark image

S 12361 lat CXRS 8357

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

EDR

Exposure Data Recognition When laser scans it is looking for area of

plate that has exposure Some read from center out and look for

two sides of collimation Works best when image centered

Exposure Indicators

Imaging plates get a signal from the exposure they receive

The value of the signal is calculated from the region identified as the anatomy of interest

The signal for the plate is an average of all signals given to the plate

Exposure Values

Each system has range of values for appropriate exposure for part

The range used by vendor is very broad Each facility should develop its own

exposure range taking into accountRadiologist preferenceALARA

S numbers Index numbers Sensitivity numbers Exposure index

The total signal is not a measure of the dose to the patient but indicates how much radiation was absorbed by the plate

A 1 mR exposure will giveFuji S 200KodakCarestream EI 2000Agfa 200 speed lgm reference value for site

EXPOSURE VALUES

Exposure indicatorPlates sensitive to 01 mR ndash 100 mR ldquoSrdquo number for Fuji

S number inverse to exposureS=2 (100 mR) S=200 (1 mR)

CarestreamKodak uses exposure index ndash direct relationship2000 (1 mR) 3000 (10 mR)

Using Exposure Numbers

Fuji if appropriate is 200 thenAt 400 too light double mAs for 200At 100 too dark half mAs for 200

Kodak if appropriate is 1800At 1500 too light double mAs for 1800At 2100 to dark half mAs for 1800

Exposure Numbers

The exposure numbers can only be used if all other parameters are correctCentering to plateCollimation

Position over AEC look at mAs readout to determine if poor positioning caused light or dark image

S 12361 lat CXRS 8357

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Exposure Indicators

Imaging plates get a signal from the exposure they receive

The value of the signal is calculated from the region identified as the anatomy of interest

The signal for the plate is an average of all signals given to the plate

Exposure Values

Each system has range of values for appropriate exposure for part

The range used by vendor is very broad Each facility should develop its own

exposure range taking into accountRadiologist preferenceALARA

S numbers Index numbers Sensitivity numbers Exposure index

The total signal is not a measure of the dose to the patient but indicates how much radiation was absorbed by the plate

A 1 mR exposure will giveFuji S 200KodakCarestream EI 2000Agfa 200 speed lgm reference value for site

EXPOSURE VALUES

Exposure indicatorPlates sensitive to 01 mR ndash 100 mR ldquoSrdquo number for Fuji

S number inverse to exposureS=2 (100 mR) S=200 (1 mR)

CarestreamKodak uses exposure index ndash direct relationship2000 (1 mR) 3000 (10 mR)

Using Exposure Numbers

Fuji if appropriate is 200 thenAt 400 too light double mAs for 200At 100 too dark half mAs for 200

Kodak if appropriate is 1800At 1500 too light double mAs for 1800At 2100 to dark half mAs for 1800

Exposure Numbers

The exposure numbers can only be used if all other parameters are correctCentering to plateCollimation

Position over AEC look at mAs readout to determine if poor positioning caused light or dark image

S 12361 lat CXRS 8357

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Exposure Values

Each system has range of values for appropriate exposure for part

The range used by vendor is very broad Each facility should develop its own

exposure range taking into accountRadiologist preferenceALARA

S numbers Index numbers Sensitivity numbers Exposure index

The total signal is not a measure of the dose to the patient but indicates how much radiation was absorbed by the plate

A 1 mR exposure will giveFuji S 200KodakCarestream EI 2000Agfa 200 speed lgm reference value for site

EXPOSURE VALUES

Exposure indicatorPlates sensitive to 01 mR ndash 100 mR ldquoSrdquo number for Fuji

S number inverse to exposureS=2 (100 mR) S=200 (1 mR)

CarestreamKodak uses exposure index ndash direct relationship2000 (1 mR) 3000 (10 mR)

Using Exposure Numbers

Fuji if appropriate is 200 thenAt 400 too light double mAs for 200At 100 too dark half mAs for 200

Kodak if appropriate is 1800At 1500 too light double mAs for 1800At 2100 to dark half mAs for 1800

Exposure Numbers

The exposure numbers can only be used if all other parameters are correctCentering to plateCollimation

Position over AEC look at mAs readout to determine if poor positioning caused light or dark image

S 12361 lat CXRS 8357

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

S numbers Index numbers Sensitivity numbers Exposure index

The total signal is not a measure of the dose to the patient but indicates how much radiation was absorbed by the plate

A 1 mR exposure will giveFuji S 200KodakCarestream EI 2000Agfa 200 speed lgm reference value for site

EXPOSURE VALUES

Exposure indicatorPlates sensitive to 01 mR ndash 100 mR ldquoSrdquo number for Fuji

S number inverse to exposureS=2 (100 mR) S=200 (1 mR)

CarestreamKodak uses exposure index ndash direct relationship2000 (1 mR) 3000 (10 mR)

Using Exposure Numbers

Fuji if appropriate is 200 thenAt 400 too light double mAs for 200At 100 too dark half mAs for 200

Kodak if appropriate is 1800At 1500 too light double mAs for 1800At 2100 to dark half mAs for 1800

Exposure Numbers

The exposure numbers can only be used if all other parameters are correctCentering to plateCollimation

Position over AEC look at mAs readout to determine if poor positioning caused light or dark image

S 12361 lat CXRS 8357

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

EXPOSURE VALUES

Exposure indicatorPlates sensitive to 01 mR ndash 100 mR ldquoSrdquo number for Fuji

S number inverse to exposureS=2 (100 mR) S=200 (1 mR)

CarestreamKodak uses exposure index ndash direct relationship2000 (1 mR) 3000 (10 mR)

Using Exposure Numbers

Fuji if appropriate is 200 thenAt 400 too light double mAs for 200At 100 too dark half mAs for 200

Kodak if appropriate is 1800At 1500 too light double mAs for 1800At 2100 to dark half mAs for 1800

Exposure Numbers

The exposure numbers can only be used if all other parameters are correctCentering to plateCollimation

Position over AEC look at mAs readout to determine if poor positioning caused light or dark image

S 12361 lat CXRS 8357

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Using Exposure Numbers

Fuji if appropriate is 200 thenAt 400 too light double mAs for 200At 100 too dark half mAs for 200

Kodak if appropriate is 1800At 1500 too light double mAs for 1800At 2100 to dark half mAs for 1800

Exposure Numbers

The exposure numbers can only be used if all other parameters are correctCentering to plateCollimation

Position over AEC look at mAs readout to determine if poor positioning caused light or dark image

S 12361 lat CXRS 8357

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Exposure Numbers

The exposure numbers can only be used if all other parameters are correctCentering to plateCollimation

Position over AEC look at mAs readout to determine if poor positioning caused light or dark image

S 12361 lat CXRS 8357

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

S 12361 lat CXRS 8357

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Same technique different centering and collimation

S 592S 664

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Histogram Analysis Collimation is very important

If plate reader cannot find collimated edges then all the exposure on plate will be included in the histogram

Histogram from plate is compared to body part histogram stored in computer

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Characteristic curve amp histogram

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Histogram with HampD curve

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Underexposed

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Overexposed

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Just right

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Changes to Histogram

Hip prosthesis

Line caused from dirt collected in a CR Reader

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Higher kVp

bull Smaller signal difference

bull Narrower data range

bull Photons to IR

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Lower kVp

bull Larger signal difference

bull Wider data range

bull More photons will be absorbed

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

kVp vs Data Width

bull Very difficult concept for radiographer

bull Focused on exposure vs appearance

bull High kVp = longer scale = wider

bull Low kVp = shorter scale = narrower

bull Change focus to underlying physics

bull High kVp = less differential attenuation

bull Smaller signal difference

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

LUT Look Up Table (LUT) Each anatomic area has a LUT or

Algorithm Used to adjust contrast and density Other terms that may be used for this

Contrast rescalingContrast processingGradation processingTone scaling

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

LUT

The image data from the histogram is rescaled for application of the LUT

The LUT maps the adjusted data through a ldquoSrdquo curve that is similar to an H amp D curve

The result is an image that has the correct contrast and brightness (density)

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Automatic rescaling

Mapping grayscale to ldquopixel values of interestrdquo to achieve specific display levels

Critical elementsPeaksTroughsWidthLocates VOI (values of interest)Exposure index determination

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

LUT

1 is unprocessed 2 algorithm finds anatomy 3 finished

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Myths for CR 1 amp 2

1 mAs ndash myth digital is mAs driven Truth

2 kVp ndash myth digital is kVp driven Truth

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Contrast

What determines contrast Which factors have more impact on contrast than

kVp for all systems Anatomical structure Contrast media Grid utilization Grid vs non-grid Grid efficiency Processing algorithm

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

TECHNIQUE CONISDERATIONS

kVp energy dependant

Now COMPUTER controls CONTRAST

Higher kVp to stimulate electron trapskVp range for CR 45 - 120

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Using Higher kVp with Digital

There is a limit If higher kVp is used to limit doseRemember basic physics

Higher kVp ndash more transmission Lower kVp ndash more photoelectric Too low mAs can cause quantum mottle

regardless of kVp used

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

kVp Selection

Anatomical contrast Inherent Δ attenuation due to structure Grid utilization Yes No Efficiency

Ratio frequency lead content Contrast improvement Default processing algorithm

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

kVp Selection

Determined by anatomy and grid Adults 1048707 Optimal range 60 ndash 120 1048707 Pediatrics lt 100 lbs Optimal range 50 -

90 May use higher kVp than with SF Helps limit dose increase Narrows acquired data range

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

kVp ranges for CR

Infant extremities 50 - 60 kVp

Adult extremities 65 - 75 kVp

Bucky extremities 75 ndash 90 kV

AP spine 85 - 95 kVp

Lateral spine 85 ndash 100 kVp

Chest 110 ndash 130 kVp Skull 80 ndash 90 kVp

Only 1 kVp is not reccomended

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Another set of suggested kVp ranges Distal Extremities =

65 ndash 75 Ped extremities = 50

- 65 KUB = 80 - 85 IVU = 70 ndash 80 BE = 110 -120

Grid extremities = 85 - 90

L-spinePelvis = 85 ndash 90 Chest grid = 110 ndash 130 Ped chest NG 70 ndash 80 Ribs = 80 ndash 90 T-spine = 90 ndash 100

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Collimation

Proper collimation is the best way to enhance your CR image Why

What is shuttering

Is it the same as collimating

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Myths for CR 3

Collimation ndash myth you cannot collimateTruth

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Shuttering

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

If radiologist objectApply back border

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Collimation

Collimation Less water irradiated Less scatter produced Improves contrast Reduces effective dose Reduces automatic rescaling errors

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Exposure Field RecognitionIf the exposure field is not recognized the entire plate is used in image construction

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Myths for CR 4

Grid ndash myth cannot use grids and donrsquot need them Truth

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Grid vs Non-grid

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Myths for CR 5

5 SID ndash myth magnification doesnrsquot occur with digital so SID is unimportant Truth

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Myths for CR 6

Speed class ndash myth it is a 200 speed class you need to double your mAs and increase your kVp by 10 Truth

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Myth for CR 7 amp 8

7 Fog ndash myth digital systems canrsquot be fogged by scatter or background radiation Truth

Myth fluorescent lights fog PSP plates Truth

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

ADVANTAGE OF CRDR vs FS

Rapid storage retrieval of images NO LOST FILMS PACS (storage management) Teleradiology - long distance transmission

of image information Economic advantage - at least in the long

run

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

ADVANTAGE OF CRDR

Can optimize image quality by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Image Preprocessing

Data recognition is very important

Two on one imaging Can it be done Is it good practice

Carter pg 87

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Improves Exam Times Improves Exam Times

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

High resolution with digital imaging

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

NEW IMAGEbull towel that was used

to help in positioning a child

bull CR is MORE sensitive to

bull ARTIFACTS

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE

Questions

• Digital Imaging
• Development of Digital Imaging
• First-generation CT unit dedicated head scanner (Photograph taken at Roentgen Museum Lennep Germany)
• Methods to Digitize an Image
• Slide 11
• Conventional radiography latent image formation
• CR latent image formation
• Slide 19
• Slide 24
• Slide 38
• Slide 41
• Basics of Digital Images
• Matrix = each cell corresponds to a specific location on the image
• Pixel
• Slide 49
• Digital Images ndash Bit Depth
• Display Bit Depth 1 bit 6 bit 8 bit
• Screen Film Imaging = self regulating
• CR imaging results in 10000 shades of gray Fixed kVp exposures
• Slide 65
• Slide 66
• Workstation Menu
• Wrong Algorithm
• Slide 72
• Slide 83
• Same technique different centering and collimation
• Slide 85
• Characteristic curve amp histogram
• Histogram with HampD curve
• Underexposed
• Overexposed
• Just right
• Changes to Histogram
• Higher kVp
• Lower kVp
• kVp vs Data Width
• Slide 99
• Slide 104
• Shuttering
• If radiologist object Apply back border
• Slide 114
• Exposure Field Recognition If the exposure field is not recognized the entire plate is used in image construction
• Slide 116
• Slide 117
• Slide 118
• Slide 119
• Slide 120
• Grid vs Non-grid
• NEW IMAGE