section 03 reference images · the tuffest stuff ct registry review solution major components of...

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SECTION 03REFERENCE IMAGES

MIKE ENRIQUEZ, MPA, BSRT(R)(CT)

AUTHOR/PRESENTER

THE TUFFEST STUFF CT REGISTRY REVIEW SOLUTION

MAJOR COMPONENTS

ofThe

CT IMAGING CHAIN

X-ray Tube (1.)

The Generator (2.)

The Beam Shaping Filter (3.)

Pre-patient Collimator (4.)

PATIENT

Pre-Detector Collimator (5.)

Detector Array (6.)

Analog-to-Digital Converter (7.)

CT Computer, aka, Array Processor (8.)

Digital-to-Analog Converter (9.)

Monitor (10.)

[email protected] 209-617-4468 The Tuffest Stuff CT Registry Review

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Scale of Contrast


Long Scale, Wide Window Short Scale, Narrow Window

THE WIDER THE WINDOW, THE LONGER THE SCALE, THE GRAYER THE IMAGE;WIDE WINDOWS RANGE FROM 500 – 2000;

WIDE WINDOWS ARE GOOD FOR BONY DETAIL

THE NARROWER THE WINDOW, THE SHORTER THE SCALE, THE MORE BLACK & WHITE THE IMAGE;

NARROW WINDOWS RANGE FROM 0 - 499;NARROW WINDOWS ARE GOOD FOR SOFT TISSUE DETAIL

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Short vs. Long Scale“The wider the window, the longer the scale”

“The narrower the window, the shorter the scale”


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Which area of the spectrum represents higher ENERGY?

Short Wavelength, High Frequency = High EnergyLong Wavelength, Low Frequency = Low Energy


FAMILY MEMBER CHARACTERISTICS• NO MASS• NO CHARGE• TRAVEL @ C

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ACQUISITION GEOMETRIES


WITH HELICAL, INTERPOLATION OF DATA IS NECESSARY; ALSO, OVER-RANGING IS AN ISSUE

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BEAM GEOMETRIES

•Cone Beam• Fan beam + expanded Z axis as it

exits from the patient and covers the length & width of the detectors

• MDCT SYSTEMS: 3rd & 4th

generation CT Systems

•Area Beam• Like that used in diagnostic to

obtain a KUB

• Includes X, Y & Z axes in CT


•Pencil Beam• Like that of a laser pointer

• 1st generation CT Systems only

•Fan Beam• The inverted V of beam

that covers the patient as in the SFOV

• 2nd, 3rd & 4th generation CT System

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THE DATA ACQUISITION SYSTEM

• PRIMARY COMPONENTS

• THE CT DETECTOR SYSTEM• Convert EM energy to Electrical

energy

• Xenon gas

• Scintillation photodiode

• THE ANALOG TO DIGITAL CONVERTER (ADC)• Convert electrical impulses to

Binary Data


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THE 6 STEPS OF RECONSTRUCTION

• FROM THE CT DETECTORS TO THE ADC TO THE CT COMPUTER…

1. PREPROCESSING

• Filter SCAN DATA = MEASUREMENT DATA and correct for data set errors due to beam hardening, bad detector reading, scatter radiation

2. REFORMATTED RAW DATA

• This is scan data that has been corrected by preprocessing

3. CONVOLUTION WITH FILTER

4. IMAGE RECONSTRUCTION ALGORITHM

• Back projection of convolved data

5. RECONSTRUCTED IMAGES OF CT NUMBERS

6. IMAGE STORAGE, DISPLAY, RECORDING, ARCHIVING


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Important Cerebral Anatomy


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1. Superior sagittal sinus2. Frontal bone3. Lateral ventricle, anterior horn4. Head of the caudate nucleus5. Putamen6. Third ventricle7. Choroid plexus8. Parietal bone9. Inion10. Cerebellar vermis11. Pineal body12. Thalamus13. Internal capsule


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ACQUISITION GEOMETRIES• 1st Generation

• Rotate-translate system

• Pencil beam scanning

• 2nd Generation

• Rotate-translate system

• Fan beam scanning

• 3rd Generation

• Rotate-rotate system


• 4th Generation

• Rotate only system


• 5th Generation• High speed CT scanners

• Obtain images in mS

• Electron beam CT Scanner

• Dynamic Spatial Reconstructor

• 6th Generation• Dual source CT scanner

• 2 tubes & 2 detector systems• Offset by 90 degrees

• Variable kVp

• 7th Generation• Flat panel CT Scanner


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1. Maxillary bone2. Oral vestibule3. Masseter muscle4. Ramus, mandible5. Atlas6. Dens7. Spinal cord8. Internal jugular vein9. Mastoid tip10. Parotid gland11. Retromandibular vein12. Internal carotid artery13. pharynx14. Genioglossus muscle15. Vertebral artery16. Vertebra, spinous process17. Longus colli muscles18. Rectus/oblique capitus

muscle19. Splenius capitus muscle20. Pterygoid muscle21. External carotid artery


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Top of the Aortic Arch


1. Brachiocephalic Artery = Innominate Artery

A. Right Common Carotid ArteryB. Right Vertebral ArteryC. Right Subclavian Artery

2. Left Common Carotid Artery

3. Left Subclavian ArteryD. Left Vertebral

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Circle of Willis

• ARTERIAL COMPOSITION• LEFT & RIGHT ANTERIOR CEREBRAL

ARTERIES

• ANTERIOR COMMUNICATING ARTERY

• LEFT & RIGHT INTERNAL CAROTID ARTERY

• POSTERIOR CEREBRAL ARTERY

• POSTERIOR COMMUNICATING ARTERY

• BASILAR ARTERY


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Circle of Willis


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1. Frontal lobe2. Medial rectus muscle3. Superior rectus muscle4. Infraorbital fissure5. Nasal conchae6. Maxillary sinus7. Zygoma8. Maxillary bone9. Hard palate10. Mandible11. Tooth12. Nasal septum13. Inferior rectus muscle14. Lateral rectus muscle15. Optic nerve16. Sphenoid sinus17. Tongue18. Oral vestibule19. Masseter [email protected] 209-617-4468

The Tuffest Stuff CT Registry Review20

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CARDIAC ANATOMY & CIRCULATIONCORONARY ARTERY DETAILS1. Both the R & L main coronaries

arise from the base portion of the aorta

2. Both the R & L main coronaries lie on the epicardial surface & then branch

3. Venous return to the right atrium occurs via the coronary sinus

1. Important branches1. Great cardiac vein (Lt.

coronary vein)2. Middle cardiac vein3. Small cardiac vein


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1. Pectoralis major muscle2. Pectoralis minor muscle3. Ribs4. Aortic arch5. Vertebra6. Lung7. Pulmonary vessels8. Scapula9. Infraspinatus muscle10. Trachea11. Right brachiocephalic vein12. Left brachiocephalic vein13. Brachiocephalic artery14. esophagus


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1. Sternum2. Pulmonary artery3. Ascending aorta4. Left atrium5. Descending aorta6. Vertebra7. Left inferior pulmonary vein8. Spinal cord9. Esophagus10. Right inferior pulmonary vein11. Superior vena cava12. Right atrial appendage13. lungs


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1. Right ventricle2. Aortic root3. Aortic valve4. Left anterior descending aorta5. Left ventricle6. Left atrium7. Descending aorta8. Left inferior pulmonary vein9. Spinal cord10. Vertebra11. Trapezius muscle12. Erector spinae muscle13. Azygos vein14. Esophagus15. Right inferior pulmonary vein16. Right lower lobe bronchus17. Right atrium18. Ribs19. Right coronary artery20. Left circumflex coronary artery


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LEFT

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1. 1st cuneiform2. 2nd cuneiform3. 3rd cuneiform (lateral)4. Cuboid5. Navicular6. Calcaneus10. Achilles tendon


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1. Extensor tendons2. Trapezium3. Scaphoid4. Capitate5. Hamate6. Triquetrum7. Pisiform8. Abductor &

opponensmuscles

9. Flexor tendons10.Radial artery11.Radial vein


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CERVICAL VERTEBRA (be able to label)


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TYPICAL THORACIC VERTEBRA (be able to label)


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Typical LUMBAR (be able to label)


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ABDOMINAL VASCULATURE


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Abdomen Anatomy Review


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• FATTY LIVER INFILTRATION

If the spleen measures 10 or more HU greater than the liver, a fatty liver is indicated; or,If the liver measures 10 or more HU less than the spleen, a fatty liver is indicated


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Pancreatic Anatomy


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CORTICO-MEDULLARY NEPHROGRAM EXCRETORY


30-70 sec. POST-Bolus 100-120 sec. POST-Bolus 3-16 min. POST-Bolus

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1. Falciform ligament3. Magenblase4. Barium-filled stomach5. Spleen8. Left adrenal gland11. Aorta12. Inferior vena cava13. Portal vein14. Liver17. Transverse colon18. Splenic vein19. Cortex, left kidney20. Medulla, left kidney21. Vertebra22. Right adrenal gland23. Pancreas


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2. Duodenum4. colon, splenic flexure5. Spleen9. Aorta10. Inferior vena cava12. Liver15. Rectus abdominus muscle17. Pancreatic head18. Portal vein confluence19. Jejunum20. Superior mesenteric artery21. Left renal vein22. Right kidney23. Psoas muscle24. Erector spinae muscle25. Gall bladder


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UPPER ABDOMINAL ARTERIES


CELIAC AXIS ARTERIES• SPLENIC ARTERY• COMMON HEPATIC ARTERY

SUPERIOR MESENTERIC ARTERY

RIGHT & LEFT RENAL ARTERIES

INFERIOR MESENTERIC ARTERY

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Thoracic & Abdominal Veins

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AZYGOS & HEMI-AZYGOS VEINS


FACTS:1. Innominate = Brachiocephalic2. Azygos connects the IVC & SVC

1. Courses the right vertebral column2. Azygos origin at pre-renal portion

of the IVC3. Azygos drains into the SVC

3. Hemi-azygos:1. Courses the left vertebral column2. Communicates with the Azygos at

the level of T-74. Accessory Hemi-azygos

1. Receives venous return from:1. Oblique vein of Lt. Atrium2. Coronary Sinus

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Hepatic-Portal System


H-P SYSTEM CONTRIBUTING VEINS

• SUPERIOR MESENTERIC VEIN• INFERIOR MESENTERIC VEIN• GASTRO-SPLENIC VEIN

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1. Bladder2. Left external iliac artery3. Left external iliac vein4. Obturator internus muscle5. Seminal vesicles6. Rectum7. Coccyx8. Ischium9. Femoral head10. Pubis11. Right external iliac artery12. Right external iliac vein13. Rectus abdominus muscle14. Quadriceps femoris muscle15. Prostate gland16. Iliopsoas muscle17. Sartorius muscle18. Femoral head19. Gluteus maximus muscle20. Gluteus minimus muscle21. Gluteus medius muscle22. Tensor fascia lata muscle


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1. Bladder2. Sigmoid colon5. Gluteus minimus muscle6. Gluteus medius muscle7. Ovaries8. Uterus w/ IUD9. Ilium10. Gluteus maximus muscle11. Sacrum12. Piriformis muscle13. Rectum15. Iliacus muscle16. Right external iliac artery18. Rectus abdominusmuscle


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SYSTOLE is DEMONSTRATED- the AV VALVES are CLOSED; the SEMILUNAR VALVES are OPEN.Also, “LUB” occurs when the AV Valves CLOSE. “DUB” occurs when the SEMILUNAR VALVES CLOSE.


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• Blood travels to and from heart via the great vessels

• KNOW THESE:• Aorta

• Pulmonary Trunk/Arteries

• Pulmonary Veins

• Superior Vena Cava

• Inferior Vena Cava


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Let’s Study This…

[email protected] 209-617-4468 The Tuffest Stuff CT Registry Review 52

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Tachy-, Brady- & the ECG

• Tachycardia- ECG

• Resting heart rate of greater than or equal to 100 beats per minute


Tachy-, Brady- & the ECG

• Bradycardia- ECG

• Resting heart rate of under 60 beats per minute

• Usually not symptomatic until 50 beats per minute or less


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Cardiac Gating

Prospective

• A signal from the R-wave triggers scanning at a set point in the R-R interval

• In this way only a portion of the cardiac cycle is used

• Low dose procedure comparatively

• Used for calcium scoring

Retrospective

• Continuous acquisition throughout the cardiac cycle with simultaneous recording of the ECG.

• Data can be reconstructed at any point in the R-R interval.

• Cine loops can be generated

• Higher radiation dose


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A Convolution “kernel”The averaging of 9 values to create 1 value

As applied to raw data


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“PITCH” Exists because Slice “PITCH” is Real!

“PITCH” is the term that describes the relationship between tube rotation, table indexing and beam width at the detectors

As SLICE “PITCH” increases, the value of “PITCH” increases


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“PITCH” Exists because Slice “PITCH” is Real!

“PITCH” is the term that describes the relationship between tube rotation, table indexing and beam width at the detectors

As SLICE “PITCH” increases, the value of “PITCH” increases


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HELIX Expansion, HELIX Contraction


AS THE HELIX EXPANDS, PITCH INCREASES

AS THE HELIX CONTRACTS,

PITCH DECREASES62

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“PITCH” relationships…

• INTERPRETING the diagram…• AS “P” increases:

• “PITCH” increases,

• dose decreases,

• slice pitch increases, • anatomy covered

per tube rotation increases; and,

• resolution decreases


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“PITCH” relationships…

• INTERPRETING the diagrams…• AS “P” decreases:

• “PITCH” decreases,

• dose increases,

• slice pitch decreases, • anatomy covered

per tube rotation decreases; and,

• resolution increases


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“Pitch”, the Helix, Dose & Resolution

• As the helix expands, “pitch” Increases• Dose & Resolution

DEcrease

• As the helix contracts, “pitch” Decreases

• Dose & Resolution INcrease


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CT specific patient dose measures• DLP takes into account the entire scanned volume and

tissue irradiated

• Can multiply by weighting factor to get effective dose

• DLP represents an improved method for estimating patient dose (e.g., effective dose)


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CT Specific MeasuresEstimating Effective Dose in mSvApplying k values for Adults

• Effective dose = DLP x k (where k is the weighting factor)• Representative adult weighting factors for k are:

»Head/Neck .0031»Head .0021»Neck .0059» Chest .014»Abdomen .015

–IF, DLP = 251 mGy-cm for a CHEST CT–THEN, Effective dose = DLP or 251 mGy-cm x 0.014 (k) = 3.5 mSv

PEDIATRIC CHART:AAPM Report No. 96These are k factor charts for kids aged 0 -1 -5 -10


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Dose uniformity decreases as SFOV and patient thickness increases


100 rad = 1.0 Gy = 1,000 mGy10 rad = 0.10 Gy = 100 mGy1 rad = 0.01 Gy = 10 mGy1.2 rad = 0.012 Gy = 12 mGy3.1 rad = 0.031 Gy = 31 mGy3.3 rad = 0.033 Gy = 33 mGy3.5 rad = 0.035 Gy = 35 mGy4.0 rad = 0.040 Gy = 40 mGy4.1 rad = 0.041 Gy = 41 mGy4.4 rad = 0.044 Gy = 44 mGy4.5 rad = 0.045 Gy = 45 mGy5.0 rad = 0.050 Gy = 50 mGy

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From Achieving Ideal Computed Tomographic Scan Length in Patient With Suspected Urolithiasis

Overranging/Z-Axis Overscanning


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Acquisition Parameter Settings

Detector Configuration


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Soft tissue ww=400, wl=40


Bone window ww=2000, wl=150Brain window ww=100, wl=35

Window Samples(Brain)

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ARTIFACT REVIEW- PART 1

MOTION METALSTREAK

OUT-OF-FIELD


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ARTIFACT REVIEW- PART 2

BEAM HARDENING

METALSTREAK

WINDMILL RING


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Injection rate controls the time to peak enhancement

As injection rate increases, the time to peak enhancement decreases; and/or,

As injection rate decreases, the time to peak enhancement increases.


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