Imaging - CT, Questions -- Image Production-- (CT Boot camp) -- Image Post-Processing, Imaging: CT, CT Imaging Procedures Board Review

HU of Dense bone

1000

How do you calculate the CT number (Hounsfield units = HU)?

1000 x (Tissue density - water density)/(water density) ranges: -1000 to +3000

HU of CSF

15

HU of blood

20

gray level =

2^(# of bits)

HU of grey matter

40

In obtaining a 4DCT, if breathing amplitude is more than ___, you need to limit amplitude in order to deliver SBRT

5 mm (per TG-76)

HU of muscle

50

MRI guided radiation therapy only has ___ MV photon energy FFF

6 MV - MRIdian 7 MV - Unity (7MV FFF PDD is similar to conventional 6MV with FF) either way, MRI linac only has a single photon energy

1 bite = ___ bites

7

1 byte = ____ bits

8

CT Sim Bore Size

80-90cm

Consider a voxel in a mutliplanar reformation that includes equal portions of air, blood, and bone. What Hounsfield Unit (HU) will be displayed on the pixel? A.The average of all HU in the voxel B.The HU for water C.The HU for fat D.The HU for bone

A

Which of these 3D rendering techniques display only one tissue type? A. Shaded surface display B. Volume rendering C. Maximum intensity projection D. Minimum intensity projection

A

Which of these axial data would be best suited for creating 2.5mm coronal reformatted images through the abdomen? A.1.25 mm axial images B.2.5 mm axial images C.5 mm axial images D.10 mm axial images

A

3) 100 ml at 4ml/s

A CT scan is requested to evaluate a patient for a thoracic aorta aneurysm. The patient weighs 147 pounds, they have a history of COPD, and they are in acute renal failure. Which of these contrast injection parameters would be ideal for this patient? 1) 100 ml at 3ml/s 2) 150 ml at 4ml/s 3) 100 ml at 4ml/s 4) 150 ml at 3ml/s

3) Bolus tracking in the descending aorta

A Type-B aortic dissection should be evaluated using which of these contrast-timing methods? 1) 30 second scan delay time 2) Bolus tracking in the pulmonary arteries 3) Bolus tracking in the descending aorta 4) Non-contrast

3) Both prospective and retrospective gating

A cardiologist requests coronary images at 50%-75% of the R-to-R interval. What gating method can accomplish this request? 1) Prospective gating 2) Retrospective gating 3) Both prospective and retrospective gating 4) No gating is required

3) CT chest in venous phase

A diagnosis of hilar adenopathy is an indication for which of these imaging protocols? 1) CTA chest of the thoracic aorta 2) CTA chest for PE 3) CT chest in venous phase 4) CT high resolution chest

3) CT chest in venous phase

A general survey of the chest for a trauma patient should be completed using which of these CT protocols? 1) CTA chest of the thoracic aorta 2) CTA chest for PE 3) CT chest in venous phase 4) CT high resolution chest

3) Fewer images

A general survey of the sinuses is requested on a 35 year old female with chronic sinusitis. Compared to 1.25 mm slices, 3.75 mm slices will result in which of the following? 1) More image noise 2) More spatial resolution 3) Fewer images 4) Lower dose

What is a histogram?

A histogram is a graph of the frequencies of each pixel value (HU) within the CT images.

3) 45 second scan delay time

A known blood clot in the transverse sinus of the brain could be best evaluated with which IV contrast timing method? 1) Bolus tracking in the ascending aorta 2) Timing bolus monitoring in the internal carotid artery 3) 45 second scan delay time 4) 90 second scan delay time

1) Scan delay time

A new CT protocol requires scanning the liver at exactly 25 seconds after initiating IV contrast injection. This can be accomplished by which scan timing method? 1) Scan delay time 2) Test bolus 3) Bolus tracking

4) CT myelogram with intrathecal contrast

A patient arrives in the radiology department with complaints of lower pain the numbness in the lower extremities. Initial evaluation in diagnostic x-ray shows collapse of L3-L4 disc space, with a suspected ruptured disc. What protocol should be used to assess the intrusion of the ruptured disc into the spinal canal? 1) CT spine WO 2) CT spine W after a 45 second scan delay time 3) CT spine W after a 90 second scan delay time 4) CT myelogram with intrathecal contrast

1) CT abdomen pelvis W

A patient arrives in your department after a motor vehicle accident with right flank pain. What CT scan is most likely to be ordered by the attending physician? 1) CT abdomen pelvis W 2) CTA abdomen pelvis 3) CT multiphase pancreas 4) CT appendicitis

1) CTA abdomen pelvis

A patient arrives in your department for evaluation of a know renal artery stenosis. What imaging protocol should be performed? 1) CTA Abdomen pelvis 2) CTA thoracic aorta 3) CT abdomen and pelvis W 4) CTA Enterography

1) Routine head CT WO

A patient arrives in your department unresponsive. No history is known. The appropriate scan to perform is: 1) Routine head CT WO 2) Routine head CT W 3) CTA head and neck 4) CT venogram

1) CT head WO contrast

A patient diagnosed with a subdural hematoma is to be evaluated in your department. What is the correct protocol for assessing changes in the subdural hematoma? 1) CT head WO 2) CT head W 3) CTA head 4) CT head W and WO

1) CT abdomen pelvis WO

A patient experiencing acute flank pain with hematuria should be evaluated with what CT study? 1) CT abdomen pelvis WO 2) CT and pelvis W 3) CTA abdomen pelvis 4) CT multiphase kidneys

4) 400 WW and 40 WL

A patient has experienced trauma to their right eye. Soft tissue changes are best visualized with which image window? 1) 2600 WW and 500 WL 2) 400 WL and 600 WL 3) 80 WW and 40 WL 4) 400 WW and 40 WL

1) CTA chest of the thoracic aorta

A patient is brought to the ER following a MVA. The patient is experiencing severe upper back pain and an injury to the aorta is suspected. What is the best imaging protocol to evaluate the patient for this condition? 1) CTA chest of the thoracic aorta 2) CTA chest for pulmonary embolism 3) CT chest in venous phase 4) CT high resolution chest

1) CT for renal stones

A patient is presented to the ER with extreme right sided abdominal pain for 1 hour. The patient has a surgical history of appendectomy and cholecystectomy. Urinalysis demonstrate micro-hematuria. What study is likely to be used to assess this patient? 1) CT for renal stones 2) CT for PE 3) CT for aortic dissection 4) CT for renal mass

4) 5 minutes

A patient is suspected as having a tumor obstructing the valve connecting the right ureter to the bladder. This condition is best evaluated with what IV contrast scan delay time? 1) 30 seconds 2) 60 seconds 3) 90 seconds 4) 5 minutes

1) CT head WO contrast

A patient presenting with symptoms of stroke and no prior imaging should be evaluated with which CT scanning protocol? 1) CT head WO 2) CT head W 3) CTA head 4) CT head W and WO

3) MRI W

A patient presents to the radiology department for imaging of a soft-tissue tumor on the lower leg. What scan protocol should be used? 1) CT W 2) CT W intra-articular 3) MRI W 4) CT WO

3) CTA head

A patient requires imaging of a known aneurysm of the anterior communicating artery. The appropriate scan to perform is: 1) Routine head CT WO 2) Routine head CT W 3) CTA head 4) CTA head and neck

4) CT head W and WO contrast

A patient with a dental abscess is suspected as having an infection in the brain. The correct CT protocol is: 1) CT head WO 2) CT head W 3) CTA head 4) CT head W and WO

3) CT chest in venous phase

A patient with a history of cigarette smoking and COPD is suspected as having a primary lung cancer. What CT imaging procedure should be used to scan this patient? 1) CTA chest of the thoracic aorta 2) CTA chest for pulmonary embolism 3) CT chest in venous phase 4) CT high resolution chest

3) CT chest in venous phase

A patient with advanced bladder cancer needs a CT scan to check for metastatic disease in the lungs. The appropriate imaging protocol is: 1) CTA chest of the thoracic aorta 2) CTA chest for pulmonary embolism 3) CT chest in venous phase 4) CT high resolution chest

2) CTA chest for PE

A positive d-dimer test may indicate the need for which of these CT protocols? 1) CTA chest of the thoracic aorta 2) CTA chest for pulmonary embolism 3) CT chest in venous phase 4) CT high resolution chest

2) CT abdomen in multiple phases

A suspected liver mass is an indication for which of these studies? 1) CT abdomen pelvis in portal venous phase 2) CT abdomen in multiple phases 3) CT abdomen WO 4) CTA of the abdomen

3) 1 and 2 only

Advantages of helical scanning over axial scanning include: Decreased scan time Decreased patient dose Increased spatial resolution 1) 1 only 2) 2 only 3) 1 and 2 only 4) 1, 2, and 3

3) 2.5 mm slice thickness and 2.5 mm slice interval

After scanning CAP W on a trauma patient, the attending physician requests lumbar spine reconstructions to evaluate for spinal fractures. What slice parameters should be used for the axial images? 1) 1.25 mm slice thickness and 0.625 mm slice interval 2) 5.0 mm slice thickness and 5.0 mm slice interval 3) 2.5 mm slice thickness and 2.5 mm slice interval 4) 3.75 mm slice thickness and 3.75 slice interval

3) 3 only

An ER physician requests that you scan a patient's liver to evaluate for traumatic injuries. What phase of contrast should be used? 1- Non-contrast 2- Arterial phase 3- Portal venous phase 4-Delayed phase 1) 1 only 2) 2 only 3) 3 only 4) 1, 2, 3, and 4

1) CT head WO contrast

An elderly patient with a prior history of breast cancer arrives in the emergency department with sudden onset mental status change. What is the correct CT protocol for initial evaluation of the patient? 1) CT head WO contrast 2) CT head W contrast 3) CTA head 4) CT head WO and W contrast

4) CT head W and WO

An evaluation of know cerebral metastasis indicates which CT imaging procedure? 1) CT head WO 2) CT head W 3) CTA head 4) CT head W and WO

2) CTA chest PE

An ordering physician requests high-resolution images of a patient to evaluate for PE. The patient has a cough and the chest x-ray shows consolidations in the lower lungs. What is the appropriate protocol to use? 1) CTA chest of the thoracic aorta 2) CTA chest for pulmonary 3) CT chest in venous phase 4) CT high resolution chest

1) 5 ml per second

Angiographic imaging of the cerebrum can be successfully performed with which of these contrast injection flow rates? 1) 5 ml per second 2) 2 ml per second 3) 1 ml per second 4) Flow rate does not affect imaging

1) CT spine WO

Ankylosing spondylitis is an arthritic condition of the spine resulting in the fusion of adjacent vertebrae. What imaging protocol should be used to evaluate this condition? 1) CT spine WO 2) CT spine W IV contrast 3) CT myelogram 4) MRI is preferred

Third generation CT scanners

Arc of detectors Source and detector rotate in synchrony Use collimator to reduce scattered photons Fast scans (<1 sec/slice)

1) Decreased image noise 3) Decreased spatial resolution

Assume that all variables remain constant: Compared to a 1 mm reconstructed slice, a 5 mm reconstructed slice will usually result in what two changes? (Select two) 1) Decreased image noise 2) Decreased patient dose 3) Decreased spatial resolution 4) Increased image noise

1) 5.0 mm slices in a smoothing algortihm

Axial images of the CT abdomen pelvis for routine viewing are typically reconstructed as: 1) 5.0 mm slices in a smoothing algorithm 2) 1.0 mm slices in an edge-enhancing algorithm 3) 5.0 mm slices in an edge-enhancing algorithm 4) 1.0 mm slices in a smoothing algorithm

4) 1.0 mm slices in a smoothing algorithm

Axial images of the abdomen to be used for MPR should be reconstructed as: 1) 5.0 mm slices in a smoothing algorithm 2) 1.0 mm slices in an edge-enhancing algorithm 3) 5.0 mm slices in an edge-enhancing algorithm 4) 1.0 mm slices in a smoothing algorithm

1) Parallel to the hard palate

Axial imaging of the facial bones should be oriented: 1) Parallel to the hard palate 2) Perpendicular to the floor of the maxillary sinus 3) Parallel to the supraorbital meatal line 4) Perpendicular to the supraorbital meatal line

A trauma physician is requesting a 3D imaging showing several tissues with various levels of transparency. The appropriate rendering technique is: A.Shaded surface display B.Volume rendering C.Maximum intensity projection D.Minimum intensity projection

B

After completing a routine scan of the chest, the radiologist requests a sagittal image series with 5 mm slices. This request can be completed using which of these imaging techniques? A.Retrospective Reconstruction B. Multiplanar Reformation C.Histogram Analysis D.Volume Rending

B

The process of converting axial images into coronal images requires a technique called: A. Retrospective Reconstruction B. Multiplanar Reformation C. Filter back-projection D. Convolution

B

Which of the following is NOT considered a "post-processing" application of the CT image data? A. Multiplanar Reformation B. Retrospective Reconstruction C. 3D Rendering D. Region-of-Interest measurements

B

Which of these quantitative analysis methods in CT can be used to identify the maximum Hounsfield value in an area of concern? A. Region-of-interest ellipse B. Histogram analysis C. Ejection fraction D. Calcium scoring

B Histogram analysis is useful when specific hounsfield values need to be evaluated. A region of interest only shows the average hounsfield values and standard deviation. If the technologist or radiologist needs to see maximum values, the histogram must be used.

Using edge-enhanced images for volume rendering is expected to result in: A. Loss of contrast B. Image noise C. Poor spatial resolution D. Partial volume averaging

B Volume rendered images should always be created with smoothing algorithms, like the standard algorithm. Failure to do so will result in significant image noise in the 3D images. This is true even when creating volume rendered images of bones.

A physician is requesting a 3D imaging showing several tissues with various levels of transparency. The appropriate rendering technique is: A. Shaded surface display B. Volume rendering C. Maximum intensity projection D. Minimum intensity projection

B Volume rendering allows the technologist to create 3D images with different tissues and different levels of transparency. For example, volume rendering is sometimes used to create images of the thorax that show the lungs as well as the surrounding bony structures. Shaded surface display shows only one tissue at a time. Maximum intensity and minimum intensity projections cannot provide transparency.

If a radiologist needs to know the ratio of fluid to blood in a cerebral lesion, what quantitative tool can help to estimate this ratio? A. Region-of-interest ellipse B. Histogram analysis C. Ejection fraction D. Calcium scoring

B. Histogram analysis Histogram analysis is sometimes used to evaluate the frequency of specific tissue types within an area of concern. A simple region of Interest tool only shows the average of all hounsfield values, but the histogram analysis shows the frequency of all values. Histogram analysis can be used to compare the amount of blood in a lesion compared to fluid in the lesion.

Which of these measurements is NOT usually acquired using a simple region-of-interest (ROI) tool? A. Average HU value B. Maximum HU value C. Standard deviation D. Area (cm2)

B. Maximum HU value A simple region of Interest tool will show the average hounsfield values, the standard deviation, and usually the total area. The maximum hounsfield value is not displayed.

4) Incorrect windowing presentation

Based on the appearance of the following image, why is the image inappropriate for diagnostic interpretation? 1) Failure to include the entire cervical spine 2) Incorrect orientation of the sagittal reformation 3) Failure to process in the correct algorithm 4) Incorrect windowing presentation

2) 60 seconds

Based on the appearance of the image below, what scan delay time was used to acquire the image? 1) Non-contrast 2) 30 seconds 3) 60 seconds 4) 5 minutes

4) Image D

Based on the appearance of the images, which image was acquired in portal venous phase? 1) Image A 2) Image B 3) Image C 4) Image D

1) CTA of the head and neck

Based on the appearance of this image, what imaging protocol was used for this patient? 1) CTA of the head and neck 2) CTA of the Circle of WIllis 3) CT soft tissue neck 4) CT head W and WO

3) Bolus tracking in the ascending aorta

Based on the appearance of this image, what imaging protocol was used to scan the patient? 1) 30 second scan delay time 2) Bolus tracking in the pulmonary arteries 3) Bolus tracking in the ascending aorta 4) Non-contrast

1) 30 second scan delay time

Based on the appearance of this image, what imaging protocol was used to scan this patient? 1) 30 second scan delay time 2) Bolus tracking in the pulmonary arteries 3) Bolus tracking in the ascending aorta 4) Non-contrast

4) 325 psi

Based on the image below, what is the maximum intraluminal pressure that will be allowed during the IV contrast injection? 1) 4.5 ml/sec 2) 45 ml 3) 72 ml 4) 325 psi

1) Standard algortihm

Based on the smooth appearance of anatomic structures, what reconstruction algorithm may have been used to create this image? 1) Standard algorithm 2) Bone algorithm 3) Edge-enhancing

If pitch is =1 for a CT scanner, what happens?

Beams are contiguous for adjacent rotations

Explain the main similarities and differences between shaded surface display and volume rendering

Both SSD and volume rendering create 3D images. SSD processes on the surface anatomy for display, but volume rendering includes all tissues within the images

Explain the main similarities between multiplanar reformation and reconstruction.

Both reconstruction and MPR require the assignment of slice thickness and slice interval.

If a multiplanar reformation is rendered as a maximum intensity projection, what CT number will be displayed for a voxel containing mostly air, lung, fluid, and a small amount of iodinated contrast? A. The CT number for air B. The CT number for lung C. The CT number for contrast D. The average CT number within the voxel

C

The slice thickness of a reformation will affect what aspect of the resulting images? 1 - Spatial Resolution 2 - Window Width 3 - Image Noise A. 1 only B. 2 and 3 only C. 1 and 3 only D. 1, 2, and 3

C

What is the effect of using overlapping slices for volume rendered images? A. Increased image noise B. Decreased image noise C. Increased smoothing in the images D. Decreased tissue differentiation

C

Which of the statements concerning multiplanar reformations (MPRs) is TRUE? A. MPRs must be created from the raw data B. MPRs can only be produced in the same slice orientation as the image data C. MPRs must be displayed with the same algorithm as the image data D. MPRs must be displayed with the same slice thickness as the image data

C

Ejection fraction analysis in CT is used for: A. Real-time tracking of contrast enhancement B. Measuring the size of a suspicion lesion C. Evaluating the efficiency of heart contractions D. Defining the range of CT numbers in an ROI

C. Evaluating the efficiency of heart contractions The contraction of the heart chambers causes ejection of blood from one chamber to another chamber, or from one chamber into the great vessels. The efficiency of these contractions can be measured by evaluating the ejection fraction. As the ejection fraction increases, this represents highly efficient contractions of the heart. A low ejection fraction represents low efficiency and poor heart health.

Which imaging modality provides electron density information for heterogeneity based dose calculations?

CT

4) Intravenous contrast

CT evaluation of tibial neoplasm of tibial neoplasm requires which of the following contrast protocols? 1) Oral contrast 2) Rectal contrast 3) Intra-articular contrast 4) Intravenous contrast

2) Ventricular diastole

CTA images of the coronary arteries should be acquired during what phase of the cardiac cycle? 1) Ventricular systole 2) Ventricular diastole 3) Atrial systole 4) Arterial diastole

2) Aorta at the level of the diaphragm

CTA imaging of the abdomen and pelvis can be accomplished using bolus tracking in the: 1) Ascending aorta 2) Aorta at the level of the diaphragm 3) Aorta at the level of the iliac bifurcation 4) Descending aorta at the level of the carina

Imaging panel of a CBCT

Called EPID, 2D array of amorphous silicon detectors in 30x30cm. Resolution at isocenter is better because tightly packed detectors (0.25 mm)

2) Difficulty walking

Claudication is a medical term that refers to: 1) Ulceration 2) Difficulty walking 3) Loss of blood flow 4) Loss of feeling

Per TG-142, what image system needs daily QA?

Collision interlocks Positioning/repositioning (2mm normally/1mm SBRT/SRS) Image iso/treatment iso coincidence

1) Non-contrast

Consider a patient admitted to the emergency department for flank pain, hematuria, and suspected renal stone. CT imaging for the initial assessment of the collecting system should be performed during which phase of contrast enhancement? 1) Non-contrast 2) Excretory phase 3) Arterial phase 4) Portal venous phase

4) 1, 2, and 3

Consider a patient being evaluated for flank pain. If a non-contrast CT scan identifies a large hepatic tumor, what phase of contrast would be useful in further characterizing the tumor? 1- Arterial phase 2- Venous phase 3- Delayed phase 1) 1 only 2) 2 only 3) 1 and 2 only 4) 1, 2, and 3

2) Poor contrast enhancement

Consider a patient scheduled for a CTA PE scan. After testing the peripheral IV, the technologist decreases the contrast injection rate to 2.5 ml per second to avoid infiltration. This scan may lack diagnostic quality as a result of: 1) Unacceptable image noise 2) Poor contrast enhancement 3) Increased patient dose 4) Loss of spatial resolution

4) CTA Runoff

Consider a patient that arrives in your department with a weak pulse in the lower extremities. What CT protocol would be most appropriate for evaluating this condition? 1) CTA for PE 2) CTA thoracic aorta 3) CT abdomen and pelvis W 4) CTA runoff

4) CTA head and neck

Consider a patient with the symptoms of a stroke. If routine imaging shows no focal ischemia or hemorrhage, what CT procedure may be indicated? 1) CTA head and neck 2) CT head W and WO 3) CTA head 4) CTA head and neck

2) Initiating contrast injection 60 seconds prior to scanning

Contrast-enhanced imaging of the orbits (in venous phase) can be accomplished by: 1) Initiating contrast injection 30 seconds prior to scanning 2) Initiating contrast injection 60 seconds prior to scanning 3) Initiating contrast injection 120 seconds prior to scanning 4) Initiating contrast injection 15 seconds prior to scanning

Photodiode assembly

Converts light from the CT detectors to an electrical signal

Sixth generation (helical/spiral) CT scanners

Couch continuously moves toward gantry during rotation (2 rotations/sec) No interslice delay

3) CT enterography

Crohn's disease is a condition that is best imaged using which of these CT protocols? 1) CT abdomen pelvis W 2) CTA abdomen pelvis 3) CT enterography 4) CT Liver

Which of the following multiplanar reformations are impossible to create? A.1.0 mm coronal reformation from 5.0 mm axial reconstructions B.5.0 mm sagittal reformation from 1.0 mm axial reconstructions C.Bone reformation from bone algorithm reconstruction D.Standard reformation from bone algorithm reconstruction

D

Which of these methods is used to estimate a patient's risk of coronary heart disease (CAD)? A.Region-of-interest ellipse B.Histogram analysis C.Ejection fraction D.Calcium scoring

D

Patient's with an Agatston grade greater than 400 have a severe risk of major adverse cardiac events. The Agatston grade for coronary calcification is acquired using which of these methods? A. Region-of-interest ellipse B. Histogram analysis C. Ejection fraction D. Calcium scoring

D The Agatston score is created using calcium scoring in CT. The score is created by a quantitative post processing technique that measures the amount of calcium in the patient's coronary arteries.

Histogram analysis is useful for which of these applications? A. Real-time tracking of contrast enhancement B. Measuring the size of a suspicion lesion C. Evaluating the efficiency of heart contractions D. Defining the range of CT numbers in an ROI

D. Defining the range of CT numbers in an ROI Histogram analysis is a special technique which shows the frequency of specific seating numbers in a region of interest.

4) Dehydration

Spinal cord impingement is a possible effect of all of the following conditions except: 1) Disc injuries 2) Arthritic disease 3) Spinal tumors 4) Dehydration

4) MRI

Spinal ependymoma is a primary tumor of the brain or spinal cord. Suspicion of ependymoma should initially be assessed using which imaging procedure? 1) CT spine WO 2) CT spine W 3) CT myelogram 4) MRI

2) CTA neck

Stenosis of the carotid bifurcation is best evaluated with which procedure? 1) CT soft tissue neck 2) CTA neck 3) CT c-spine

1) CT soft tissue neck

Swelling in the neck (with an unknown cause) is an indication for what CT protocol? 1) CT soft tissue neck 2) CTA neck 3) CT c-spine

Data acquistion system

Takes the electrical signal from detectors, measures it and converts it into binary code, then transfers to computer

4) 15 minutes

The "delayed phase" of adrenal imaging is acquired at what scan delay time? 1) 60 seconds 2) 90 seconds 3) 4 minutes 4) 15 minutes

4) 100 ml at 4 ml/sec

The CT enterography study should use which of the following contrast injection parameters? 1) 100 ml at 3 ml/sec 2) 150 ml at 2.5 ml/sec 3) 75 ml at 5 ml/sec 4) 100 ml at 4 ml/sec

3) Thrombosis of the superior sagittal sinus

The CT venogram protocol of the head is best suited to diagnose which of these pathologies? 1) Occlusion of the internal carotid arteries 2) Dissection of the vertebral arteries 3) Thrombosis of the superior sagittal sinus 4) Subarachnoid hemorrhage

2) Motion artifact on the images

The abrupt starting and stopping of the patient table during axial scanning can result in: 1) Increased patient dose 2) Motion artifact on the images 3) Decreased scan time 4) Decreased spatial resolution from interpolation

1) Thickness of activated detector rows

The acquisition slice thickness used during a scan is determined by the technologist. Acquisition thickness refers to which of the following? 1) Thickness of activated detector rows 2) Thickness of anatomical data averaged into each image 3) Total width of the x-ray beam 4) Space between adjacent slices

1) Stranding

The appearance of inflamed tissue surrounding the appendix is called: 1) Stranding 2) Claudication 3) Hematoma 4) Hemangiomas

1) Large bowel

The appendix is an appendage of the: 1) Large bowel 2) Small bowel 3) Spleen 4) Mesentery

1) Adrenal adenoma

The arrow in the following image is pointing to a condition called: 1) Adrenal adenoma 2) Aortic aneurysm 3) IVC filling defect 4) Ovarian cyst

1) Corticomedullary phase

The arterial phase of IV contrast enhancement in the kidneys is also called: 1) Corticomedullary 2) Nephrographic phase 3) Excretory phase 4) Portal venous phase

2) 3 ml per second

The average flow rate recommended for venous phase imaging of the abdomen is: 1) 1 ml per second 2) 3 ml per second 3) 5 ml per second 4) 10 ml per second

2) Increased contrast enhancement

The benefit of increased flow rate in angiographic imaging is: 1) Decreased patient dose 2) Increased contrast enhancement 3) Decreased scan time 4) Decreased intraluminal pressure

1) Malignant

The contrast-enhancing tissues behind the eye are most likely: 1) Malignant 2) Normal 3) Bleeding 4) Inflammation

4) Peripheral catheter

The device in this image is a: 1) PICC line 2) Port 3) Dialysis catheter 4) Peripheral catheter

2) Arterial phase

The first phase of IV contrast enhancement for most organs is the: 1) Portal venous phase 2) Arterial phase 3) Delayed phase 4) Capillary phase

3) Image C

The following images were acquired on the same patient during a multiphase kidney exam. What image best demonstrates the renal collecting system? 1) Image A 2) Image B 3) Image C 4) Image D

1) Image A

The following images were acquired on the same patient during a multiphase liver study. The images are not in sequential order. Based on the appearance of the images, which image was acquired 5 minutes after IV contrast injection? 1) Image A 2) Image B 3) Image C 4) Image D

1) Small bowel

The goal of administering oral contrast for CT enterography is to fill the: 1) Small bowel 2) Large bowel 3) Stomach 4) Rectum

2) Image B

The images below were acquired on the same patient during a multiphase kidney examination. What images was acquired with a 70 second scan delay time? 1) Image A 2) Image B 3) Image C 4) Image D

Window length

The location on a digital image number scale where the levels of grey are centered around

2) Decreased risk of complications

The main advantage of CTA imaging of the coronary arteries compared to imaging in the catheterization lab is: 1) Increased spatial resolution 2) Decreased risk of complications 3) Ability to intervene immediately 4) No IV contrast is required

3) Ability to intervene immediately

The main advantage of coronary imaging in the catheterization lab compared to CTA imaging is: 1) Increased spatial resolution 2) Decreased risk of complications 3) Ability to intervene immediately 4) No IV contrast is required

3) DFOV

The major difference between these two images is the: 1) Slice thickness 2) Slice interval 3) DFOV 4) Scan type

1) Slice thickness

The major difference in the following two images is most likely the: 1) Slice thickness 2) Slice interval 3) DFOV 4) Scan type

3) 90 seconds

The nephrographic portion of the kidneys will experience maximum contrast enhancement at what scan delay time? 1) 30 seconds 2) 60 seconds 3) 90 seconds 4) 5 minutes

TG-142

Defined linac image system QA

Spatial resolution

Degree of blurring on an image. Determined by the amount and size of detectors.

Fundamental Principle of CT scanning

Density of tissue can be measured by the calculation of an attenuation coefficient

4) CTA runoff

Diabetic ulcers may be an indication for which of these CT examinations? 1) CTA for PE 2) CTA thoracic aorta 3) CT abdomen pelvis W 4) CTA runoff

Artifact

Discrepancies between the reconstructed CT numbers and the true attenuation coefficient of the object

DFOV

Display field of view. Can be set at the console. Smaller than or equal to the SFOV.

1) Reconstruction slice thickness

Displayed CT images are processed to display a specific amount of anatomical data in each image. This is the: 1) Reconstruction slice thickness 2) Reconstruction slice interval 3) Acquisition slice thickness 4) Beam width

2) Poor contrast enhancment

During a CT of the chest for PE, the technologist injects 50% of the recommended volume of contrast. How will this affect the scan? 1) Unacceptable image noise 2) Poor contrast enhancement 3) Increased patient dose 4) Loss of spatial resolution

2) Beta blockers

During cardiac CT, what medication may be administered to correct tachycardia prior to imaging? 1) Glucogen 2) Beta blockers 3) Nitroglycerin 4) Analgesics

1) Motion blur

During coronary CTA, an excessive heart rate could result in: 1) Motion blur 2) Poor contrast enhancement 3) Rising artifact 4) Vascular spasm

4) All of the answer options listed are correct

During the monitoring phase of bolus tracking you see several images showing no contrast at all. Possible explanations include: 1) The contrast injection was never initiated 2) The contrast has infiltrated 3) The saline and contrast syringes were loaded backwards 4) All of the answer options listed are correct

4) Non-contrast

Emphysema is a condition of the lung parenchyma that is best diagnosed using which of these contrast regimens? 1) 30 second delay time 2) Bolus tracking in the pulmonary arteries 3) Bolus tracking in the ascending aorta 4) Non-contrast

2) CT abdomen W in multiple phases

Evaluation of an uncharacterized pancreatic mass is best accomplished with which of these CT studies? 1) CT abdomen W in the portal venous phase 2) CT abdomen W in multiple phases 3) CT abdomen WO 4) CT enterography

4) CT sinuses screening

Evaluation of chronic sinusitis can be accomplished with which CT protocol? 1) CT neck W contrast 2) CT facial bones W contrast 3) CT facial bones WO contrast 4) CT sinus screening

2) 20 seconds

Evaluation of the in the arterial phase of IV contrast enhancement can be accomplished with what scan delay time? 1) 120 seconds 2) 20 seconds 3) 45 seconds 4) 90 seconds

3) 40 seconds

Evaluation of the neck in the venous phase of IV contrast enhancement can be accomplished with what scan delay time? 1) 10 seconds 2) 20 seconds 3) 40 seconds 4) 90 seconds

For 3D imaging, typical FOV ___ # of pixels ___ R ___

FOV 50cm, # of pixels = 512, R = 1mm/pixel

Advantages of Spiral CT

Faster scan times, lower tube heat loading, variable slice thickness, decreased image noise

2 Methods of CT image reconstruction

Filtered back projection and iterative reconstruction

2) 25 seconds

For arterial imaging of the pancreas, what scan delay time may be used? 1) 5 seconds 2) 25 seconds 3) 55 seconds 4) 90 seconds

1) 18 cm

For specialized imaging of the adrenal glands, the DFOV may be assigned as: 1) 18 cm 2) 8 cm 3) 80 cm 4) 32 cm

Anti-scatter grid

Grid from lead strips that reduce scattered radiation by absorbing scatter so increase the contrast Allows primary radiation to pass through but blocks scattered radiation (and also blocks some primary radiation so it increases exposure time and dose to patient)

4) 6 minutes

Hepatic hemangioma will fill with contrast at what scan delay time? 1) 15 seconds 2) 30 seconds 3) 60 seconds 4) 6 minutes

Narrow window width

High contrast

1) Bone algorithm

High resolution imaging of the chest may use which of these algorithms? 1) Bone algorithm 2) Standard algorithm 3) Brain algorithm 4) Smoothing algorithm

1) 1.25 mm slices with matching slice interval

High spatial resolution imaging of the facial bones can be accomplished using which of these slice parameters? 1) 1.25 mm slices with matching slice interval 2) 5 mm slices with matching slice interval 3) 5 mm slices with 2.5 mm interval 4) 1.25 mm slices with 5 mm interval

1) 1.25 mm slices

High spatial resolution imaging of the orbits is accomplished by: 1) 1.25 mm slices 2) 2.5 mm slices 3) 3.75 mm slices 4) 5 mm slices

1) 1.25 mm

High-resolution imaging of the chest should use which reconstruction slice thickness? 1) 1.25 mm 2) 2.5 mm 3) 5 mm 4) >5 mm

3) Parallel to the supraorbital meatal line

How should axial slices be oriented for imaging of the brain? 1) Parallel to the hard palate 2) Perpendicular to the floor of the maxillary sinus 3) Parallel to the supraorbital meatal line 4) Perpendicular to the supraorbital meatal line

1) Parallel to the hard palate

How should axial slices be oriented for imaging of the orbits? 1) Parallel to the hard palate 2) Perpendicular to the floor of the maxillary sinus 3) Parallel to the supraorbital meatal line 4) Perpendicular to the supraorbital meatal line

2) Perpendicular to the hard palate

How should the gantry be oriented when scanning direct coronal CT sinuses with the patient in the prone position? 1) Parallel to the hard palate 2) Perpendicular to the hard palate 3) Parallel to the supraorbital meatal line 4) Perpendicular to the supraorbital meatal line

1) Venous phase

IV injected contrast can be viewed exiting organs during which phase of enhancement? 1) Venous phase 2) Arterial phase 3) Delayed phase 4) Equilibrium phase

1) Basilar artery aneurysm

Identify the pathology visible in the image below: 1) Basilar artery aneurysm 2) Subarachnoid hemorrhage 3) Subdural hemorrhage 4) Arterial-venous malformation

2) Immediately prior to scanning

If glucagon is being administered for a CT study, when should it be given to the patient? 1) With the administration of oral contrast 2) Immediately prior to scanning 3) Thirty minutes prior to scanning 4) With the administration of rectal contrast

1) With the administration of oral contrast

If metoclopramide (reglan) is being used for a CT enterography study, when should it be administered? 1) With the administration of oral contrast 2) Immediately prior to scanning 3) Thirty minutes prior to scanning 4) With the administration of rectal contrast

3) 50 minutes prior to scanning

If oral contrast is to be visualized within the small bowels, when should the contrast be administered to the patient? 1) Immediately prior to scanning 2) 10 minutes prior to scanning 3) 50 minutes prior to scanning 4) 5 hours prior to scanning

1) Decrease contrast volume

If performing a CTA abdominal aorta study on a 90 lb. geriatric patient, how could the contrast injection protocol be changed without compromising the quality of the scan? 1) Decrease contrast volume 2) Increase contrast volume 3) Decrease injection rate 4) Increase injection rate

1) 100 ml at 3 ml/sec

Imaging of the abdomen and pelvis in the portal venous phase will usually use which of these IV contrast protocols? 1) 100 ml at 3 ml/sec 2) 150 ml at 3 ml/sec 3) 100 ml at 5 ml/sec 4) 150 ml at 4 ml/sec

3) Rectal contrast

In the following image, the absence of contrast media in the descending colon likely means that the patient did not receive: 1) IV contrast 2) Oral contrast 3) Rectal contrast 4) Intra-articular contrast

4) Occlusion

In the following image, the right internal jugular vein has experienced which of the following? 1) Stenosis 2) Dissection 3) Aneurysm 4) Occlusion

1) Colitis

In the image below, the arrow is pointing at a condition called: 1) Colitis 2) Appendicitis 3) Hepatitis 4) Pancreatitis

1) The patient standing after the contrast injection

In the image below, the high concentration of contrast in the inferior portion of the intrathecal space could be a result of: 1) The patient standing after the contrast injection 2) The patient laying supine after the injection 3) The patient laying prone after the injection 4) The radiologist injecting above the level of L2

1) Superior to inferior in the direction of blood flow

In what direction should the thoracic aorta be scanned when using iodinated contrast? 1) Superior to inferior in the direction of blood flow 2) Superior to inferior against the direction of blood flow 3) Inferior to superior in the direction of blood flow 4) Inferior to superior against the direction of blood flow

2) Visualization of more anatomy with decreased spatial resolution

Increasing the reconstruction slice thickness results in: 1) Visualization of more anatomy with increased spatial resolution 2) Visualization of more anatomy with decreased spatial resolution 3) Visualization of less anatomy with increased spatial resolution 4) Visualization of less anatomy with decreased spatial resolution

Relationship between window level and brightness

Indirect

1) Maintain contrast filling in the collecting system

Instructing the patient not to void prior to a urogram procedure helps to: 1) Maintain contrast filling in the collecting system 2) Maintain contrast enhancement in the circulatory system 3) Dislodge renal stones from the ureters 4) Test the patient's continence

larger pixel --> ___ (worse/better) resolution --> ___ (worse/better) SNR

Larger pixel --> worse resolution --> better SNR (tradeoff)

The only IGRT capable of 3D imaging during treatment

MRI guided radiation therapy

2) Timing bolus monitoring in the internal carotid artery

Maximum contrast enhancement for CTA imaging of the head and neck could be accomplished by: 1) Bolus tracking in the abdominal aorta 2) Timing bolus monitoring in the internal carotid artery 3) 40-second scan delay time 4) 55-second delay time

4) CT myelogram

Measuring the degree of spinal cord compression caused by spondylolisthesis is best achieved with which of these imaging protocols? 1) Routine CT spine WO 2) Routine CT spine W 3) Diagnostic radiography 4) CT myelogram

Imaging dose: kV planar imaging kV CBCT kV CT MV portal imaging MV CT MV CBCT

Most 1-5 cGy except kV planar dose which is 100x less than everything else

Per TG-142, what image system needs monthly QA?

Mostly image quality related: Isocenter coincidence Contrast resolution Spatial resolution Uniformity and noise Planar: scaling 3D only: Geometric distortion, HU constancy

What is a multiplanar reformation?

Multiplanar reformation (MPR) converts a series of axial images into coronal, sagittal, or oblique planes.

3) CT c-spine

Neck pain following a MVA is an indication for which procedure? 1) CT soft tissue neck 2) CTA neck 3) CT c-spine

2) Poor IV catheter patency

One reason for decreasing the IV injection rate during CT scanning is: 1) High-speed scanner (16 rows or more) 2) Poor IV catheter patency 3) Angiographic scanning 4) Geriatric imaging

IF a radiograph is too black, what may have occurred?

Overexposure to excessive number of xrays

Array processors

Perform the attenuation calculations at the console

4) CTA runoff

Peripheral Vascular Disease (PVD) is an indication for which of these CT protocols? 1) CTA for pulmonary embolism 2) CTA thoracic aorta 3) CT abdomen and pelvis with contrast 4) CTA runoff

Pixel size equation

Pixel size=(FOV)/Matrix size

Explain post-processing. When does it take place?

Post-processing refers to manipulations of the image data after scanning is over.

2) Arterial phase

Primary liver cancer will be brightest during which phase of IV contrast enhancement? 1) Non-contrast 2) Arterial phase 3) Portal venous phase 4) Delayed phase

4) CT myelogram W intrathecal contrast

Radiculopathy is a condition best evaluated with which of these imaging procedures? 1) CT spine WO 2) CT spine W after a 45 second scan delay time 3) CT spine W after a 90 second scan delay time 4) CT myelogram with intrathecal contrast

___ has highest resolution because detectors are finely spaced

Radiographic films

Slice pitch

Ratio of the table advance to the slice thickness

Fourth generation CT scanners

Ring of detectors Source is the only thing that rotates (ring does not move) Not possible to use collimator Fast scans (<1 sec/slice)

Spiral CT scanner

Same as helical scanning or multi-slice scanning. Captures more slices simultaneously than axial scanning

SFOV

Scanned field of view. Smaller than the aperture size. Centered in the bore.

HU of air

-1000

HU of water

0

A CBCT is generally acquired with how many rotations of the x-ray tube?

1

For treatment planning using a 4D scan, which of the following would not typically be used for dose calculation? 1. maximum intensity projection (MIP) scan 2. 3D scan 3. 3D average scan 4. scan for the deep inspiration phase

1. maximum intensity projection (MIP) scan because it OVERESTIMATES the tissue density MIP: if you have the same slice at 2 different phases, then MIP just means you take the maximum of the two pixels

2) Emphysema

The patient in the image below has experienced chronic shortness of breath for several years. Based on the appearance of the image, what is most likely the cause of their symptoms? 1) Saddle embolism 2) Emphysema 3) Type B Dissection 4) Mass lesion

Spatial uniformity

The pixel values should be constant in all regions of a uniform object

Linearity

The plot of CT number versus linear attenuation coefficient. Should be a straight line

1) Avoid contrast extravasation

The primary reason for monitoring intraluminal pressure during IV contrast injection is to: 1) Avoid contrast extravasation 2) Evaluate contrast flow rate 3) Minimize total contrast volume

1) Evenly diffuse intrathecal contrast

The purpose of rolling a patient prior to CT myelogram imaging is to: 1) Evenly diffuse intrathecal contrast 2) Loosen the intervertebral ligaments 3) Relax the spinal muscles 4) Reduce curvature of the spine

Window width

The range of CT numbers that are displayed on a grey scale

1) Occlusion of the external iliac artery

The red arrow is pointing to what abnormality? 1) Occlusion of the external iliac artery 2) Stenosis of the internal iliac artery 3) Aneurysm of the common iliac artery 4) Dissection of the superficial femoral artery

3) MIP

The technique used to create this image is called: 1) MPR 2) Volume Rendering 3) MIP 4) Shaded Surface Display

2) Nephrographic phase

The venous phase of IV contrast enhancement in the kidneys is also called: 1) Corticomedullary phase 2) Nephrographic phase 3) Excretory phase 4) Portal venous phase

If pitch is > 1 for a CT scanner, what happens?

There is a gap between beams. Larger pitch means faster scans (more table travel per rotation), and noisier images (think: lots of table travel, small slice thickness)

If pitch is < 1 for a CT scanner, what happens?

There is beam overlap. Smaller pitch means slower scans (less table travel per rotation)

1) The scan was initiated too late

This image is from a CTA PE, but the pulmonary arteries are not very well enhanced. Based on the appearance of the image, what did the technologist do wrong? 1) The scan was initiated too late 2) The scan was initiated too soon 3) The scan did not use IV contrast 4) The scan was initiated 15 seconds after injection

3) The scan should start

This image is of a bolus-tracking chart 12 seconds into contrast IV injection. What happens when threshold of 110 HU is crossed? 1) The injection should stop 2) The scan should stop 3) The scn should start 4) Nothing

1) Maximum intensity projection

This image of the brain is described as a: 1) Maximum intensity projection 2) Volume rendering 3) Sagittal reformation 4) Axial reconstruction

3) Inflammatory changes in the soft tissues of the face

This image of the lower facial bones is ideal for viewing: 1) Structural changes in the mandible 2) Bone degradation around an abscessed tooth 3) Inflammatory changes in the soft tissues of the face 4) Fractures of the facial bones

1) Normal saline was loaded in the contrast syringe

This image of the pancreas was acquired 30 seconds after initiating contrast injection. Which of the following scenarios may explain the appearance of the image? 1) Normal saline was loaded in the contrast syringe 2) Contrast was injected at 4 ml per second 3) 5.0 mm slices were used 4) The scanner was in axial mode

3) Poor enhancement of the aorta

This image was acquired to evaluate a patient for a thoracic aorta dissection. What is the main factor limiting the diagnostic quality of this scan? 1) Excessive image noise 2) Artifact obstructing the view of the anatomy 3) Poor enhancement of the aorta 4) Excessively small FOV

1) Incorrect algorithm selection

This image was presented to the radiologist for viewing the soft tissue of the brain. The appearance of excessive image noise may be a result of: 1) Incorrect algorithm selection 2) Incorrect gantry tilt 3) Incorrect WW 4) Incorrect slice interval

1) Pulmonary embolism

This is an image acquired with a 30 second scan delay time. What pathology should be reported to the attending physician? 1) Pulmonary embolism 2) Pulmonary fibrosis 3) Aortic dissection 4) Pneumothorax

2) Arterial phase

This series of images was performed on the same patient during different phases of IV contrast enhancement. A contrast-enhancing liver lesion (Arrow) is best visualized in what phase? 1) Non-contrast 2) Arterial phase 3) Portal venous phase 4) Delayed phase

How does tumor tracking differ from respiratory gating?

Tumor tracking: aperture moves with the CTV, very technically challenging but efficient delivery Respiratory gating: beam on only when CTV is within defined aperture, less efficient Both have small margins relative to ITV method

1) 30 second scan delay time

Venous-phase imaging of the chest is usually accomplished using a: 1) 30 second scan delay time 2) Bolus tracking in the pulmonary arteries 3) Bolus tracking in the ascending aorta 4) Non-contrast

1) CT orbits W

Vision changes should be evaluated in CT using which imaging protocol? 1) CT orbits W 2) CT facial bones W 3) CT sinuses WO 4) CT head WO and W

Voxel size equation

Voxel Size= pixel size x slice thickness

3) CT enterography

What CT protocol is most useful in evaluating bowel disease? 1) CT abdomen pelvis W 2) CTA abdomen pelvis 3) CT enterography 4) CT appendicitis

1) CTA abdomen and pelvis

What CT protocol should be used to diagnose abnormal narrowing of the abdominal aorta? 1) CTA abdomen pelvis 2) CTA thoracic aorta 3) CT abdomen pelvis W 4) CT enterography

4) CTA runoff

What CT protocol should be used to evaluate an arterial dissection extending from the aortic bifurcation through the popliteal arteries? 1) CTA Abdomen pelvis 2) CTA thoracic aorta 3) CT abdomen and pelvis W 4) CTA runoff

1) 100 ml at 3.0 ml per second

What IV injection protocol is most appropriate for multiphase renal imaging on an average-sized patient? 1) 100 ml at 3.0 ml per second 2) 150 ml at 3.0 ml per second 3) 100 ml at 5.0 ml per second 4) 150 ml at 5.0 ml per second

1) Curved MPR

What MPR technique can be used to visualize very tortuous coronary arteries in a single plane? 1) Curved MPR 2) Thick MPR 3) Thin MPR 4) MIP technique

1) Occlusion of the carotid arteries

What abnormality is visible in this image of a CTA head and neck scan? 1) Occlusion of the carotid arteries 2) Dissection of the vertebral arteries 3) Basilar tip aneurysm 4) Accessory vessels branching from the aortic arch

3) Abdomen and pelvis

What body cavity should be scanned when evaluating a patient for acute appendicitis? 1) Abdomen only 2) Pelvis only 3) Abdomen and pelvis 4) Chest, abdomen, pelvis

1) Prospective gating

What cardiac gating technique acquires scan data only during specific phases of the heart cycle? 1) Prospective gating 2) Retrospective gating 3) Both prospective and retrospective gating 4) No gating required

4) Non-contrast

What contrast injection protocol is necessary for diagnosis of interstitial lung disease? 1) 30 second scan delay time 2) Bolus tracking in the pulmonary arteries 3) Bolus tracking in the ascending aorta 4) Non-contrast

2) TIming bolus in the aortic arch

What contrast timing method might have been used to acquire this image of the brain? 1) Bolus tracking in the abdominal aorta 2) TIming bolus in the aortic arch 3) 45 second scan delay time 4) 60 second scan delay time

3) 45 second scan delay time

What contrast timing method was used to acquire this image of the brain? 1) Bolus tracking in the ascending aorta 2) Timing bolus monitoring in the internal carotid artery 3) 45 second scan delay time 4) 90 second scan delay time

3) 80 WW and 30 WL

What image windowing was used to display the following image? 1) 2600 WW and 500 WL 2) 400 WW and 600 WL 3) 80 WW and 30 WL 4) 400 WW and 40 WL

1) Axial

What imaging plane is best suited for viewing the pulmonary trunk where it bifurcates into the right and left pulmonary arteries? 1) Axial 2) Sagittal 3) Coronal 4) Oblique

1) CT abdomen pelvis WO

What imaging protocol in the following image? 1) CT abdomen pelvis WO 2) CT abdomen pelvis W in portal venous phase 3) CT abdomen pelvis W in arterial phase 4) CT abdomen pelvis W in renal excretory phase

3) CTA head

What imaging protocol should be followed for evaluation of a known AVM in the right upper parietal lobe? 1) CT head WO 2) CT head WO and W 3) CTA head 4) CTA head and neck

4) MRI shoulder

What imaging protocol should be used to evaluate muscular injuries within the shoulder joint? 1) CT should WO and W 2) CT shoulder W 3) CT shoulder W intra-articular contrast 4) MRI shoulder

2) CTA chest for PE

What imaging protocol was used to scan the patient? 1) CTA chest of the thoracic aorta 2) CTA chest for PE 3) CT chest in venous phase 4) CT high resolution chest

2) Maximum Intensity Projection (MIP)

What imaging technique was used to produce the image below? 1) Curved MPR 2) MIP 3) Volume rendering 4) Shaded surface display

1) 0.625 mm slices with matching interval

What is a common reconstructed slice parameter for CT angiography imaging of the brain? 1) 0.625 mm slices with matching interval 2) 3.75 mm slices with overlapping interval 3) 5 mm slices with a larger interval 4) 1.25 mm slices with a larger interval

1) 2500 WW and 600 WL

What is an appropriate windowing technique for displaying axial images of the pelvis in the bone algorithm? 1) 2500 WW and 600 WL 2) 400 WL and 600 WL 3) 80 WW and 40 WL 4) 400 WW and 40 WL

1) Bismuth eye shield

What is the bright artifact anterior to the bridge of the patient's nose? 1) Bismuth eye shield 2) EDG lead 3) Oxygen tubing 4) Motion artifact

2) Large bowel

What is the brightly enhanced structure in the LLQ of the patient imaged below? 1) Appendicitis 2) Large bowel 3) Uterine tumor 4) Urinary bladder

1) Less than 65 beats per minute

What is the ideal heart rate for coronary imaging in CT? 1) Less than 65 beats per minute 2) 65-85 BPM 3) 85-100 BPM 4) Greater than 100 BPM

3) Adrenal glands

What is the lower limit of a routine CT chest protocol? 1) Lung apices 2) Costophrenic angles 3) Adrenal glands 4) 1st lumbar vertebra

3) 1,000 ml

What is the minimum volume of rectal contrast expected to fill most of the large bowel? 1) 10 ml 2) 100 ml 3) 1,000 ml 4) 10,000 ml

3) 400 WW and 40 WL

What is the most common image window for viewing images in the standard algorithm? 1) 2500 WW and 600 WL 2) 600 WW and 2500 WL 3) 400 WW and 40 WL 4) 80 WW and 30 WL

1) Non-contrast

What is the most important phase of contrast enhancement when evaluating the kidneys for renal calculi? 1) Non-contrast 2) Excretory phase 3) Arterial phase 4) Portal venous phase

1) Different reconstruction algortihm

What is the most likely explanation for the different appearances of the following two images? 1) Different reconstruction algorithm 2) Different WW 3) Different WL 4) Different gantry tilt

1) Increased spatial resolution in the axial images

What is the purpose of reconstructing thin slices of the lungs for the high-resolution protocol? 1) Increased spatial resolution in the axial images 2) Increased contrast resolution in the axial images 3) Increased quality of multiplanar reformation 4) Decreased image noise in the axial images

1) Decreased viscosity

What is the purpose of warming IV contrast prior to injection? 1) Decreased viscosity 2) Increased radiopacity 3) Decreased chemical toxicity

3) CT facial bones without contrast

What is the recommended CT scanning procedure for a patient with traumatic injuries to the face from a motorcycle accident? 1) CT neck W contrast 2) CT facial bones W contrast 3) CT facial bones WO contrast 4) CT sinus screening

2) Perpendicular to the hard palate

What is the recommended orientation of these coronal slices? 1) Parallel to the hard palate 2) Perpendicular to the hard palate 3) Parallel to the supraorbital meatal line 4) Perpendicular to the supraorbital meatal line

3) Type B Dissection

What is the technical classification for this pathology? 1) Saddle embolism 2) Pulmonary Fibrosis 3) Type B Dissection 4) Type A Dissection

1) Type A

What is the technical classification of a thoracic aortic aneurysm that originates in the ascending aorta? 1) Type A 2) Type B 3) Type C 4) Type D

1) 400 WW and 40 WL

What is the typical image presentation for the CTA runoff procedure? 1) 400 WW and 40 WL 2) 2500 WW and 600 WL 3) 1800 WW and -600 WL 4) 80 WW and 30 WL

2) Rectal contrast

What kind of contrast may be administered immediately prior to scanning to fill the cecum of the large bowel? 1) Oral contrast 2) Rectal contrast 3) IV contrast

1) Smoothing algorithm

What kind of reconstruction algorithm is traditionally used for angiography imaging of the heart? 1) Smoothing algorithm 2) Sharpening algorithm 3) Edge-enhancing algorithm 4) Lung algorithm

3) Nitroglycerin

What medication has the effect of dilating the coronary arteries? 1) Glucagon 2) Beta blockers 3) Nitroglycerin 4) Analgesics

2) Glugagon

What medication has the effect of temporarily stopping peristalsis? 1) Metoclopramide (Reglan) 2) Glucagon 3) Nitroglycerin 4) Beta blocker

1) Metoclopramide (Reglan)

What medication helps to fill the bowels with oral contrast? 1) Metoclopramide (Reglan) 2) Glucagon 3) Nitroglycerin 4) Beta blocker

1) Aneurysm

What pathology is demonstrated by the arrow in the following image? 1) Aneurysm 2) Calcification 3) Tachycardia 4) Vascular spasm

1) Fracture of the vertebral body

What pathology is demonstrated in this image? 1) Fracture of the vertebral body 2) Fracture of the vertebral arch 3) Arthritic stenosis of the vertebral canal 4) Collapse of the intervertebral disc space

1) Appendicitis

What pathology is indicated by the arrow in the image below? 1) Appendicitis 2) Small bowel obstruction 3) Bowel perforation 4) Ovarian cyst

2) Ruptured spleen

What pathology is indicated by the arrow in the image below? 1) Ruptured liver 2) Ruptured spleen 3) Ruptured kidney 4) Ruptured aorta

2) Spinal impingement

What pathology is seen in this image? 1) Spinal metastasis 2) Spinal impingement 3) Subluxation 4) Arthritic disease

2) Calcification

What pathology is visible in the following image? 1) Aneurysm 2) Calcification 3) Tachycardia 4) Vascular spasm

1) Stenosis

What pathology is visible in the following image? 1) Stenosis 2) Calcification 3) Tachycardia 4) Vascular spasm

1) Embolism

What pathology is visible in the popliteal artery in the following image? 1) Embolism 2) Aneurysm 3) Dissection 4) Occlusion

3) Thrombosis of the superior sagittal sinus

What pathology is visible in this image? 1) Occlusion of the internal carotid arteries 2) Dissection of the vertebral arteries 3) Thrombosis of the superior sagittal sinus 4) Subarachnoid hemorrhage

1) Pancreatic tumor

What pathology is visible in this image? 1) Pancreatic tumor 2) Hepatocellular carcinoma 3) Metastatic liver cancer 4) Hemangioma of the liver

3) Portal venous phase

What phase of IV contrast enhancement best demonstrates metastatic liver cancer? 1) Non-contrast 2) Arterial phase 3) Portal venous phase 4) Delayed phase

3) Excretory phase

What phase of IV contrast enhancement is used to visualize the contrast-filled collecting system? 1) Corticomedullary phase 2) Nephrographic phase 3) Excretory phase 4) Portal venous phase

1) Non-contrast

What phase of contrast enhancement is necessary to diagnose a loss of elasticity in the lung tissues? 1) Non-contrast 2) Peak enhancement of the pulmonary arteries 3) Peak enhancement of the aorta 4) Even enhancement of entire thoracic cavity

3) Renal pelvis

What portion of the kidney is expected to experience maximum brightness at 4 minutes scan delay time? 1) Renal arteries 2) Nephrons 3) Renal pelvis 4) Renal cortex

1) Curved multiplanar reconstruction (MPR)

What post-processing technique was used to create this image? 1) Curved multiplanar reconstruction (MPR) 2) Maximum Intensity Projection 3) Volume rendering 4) Shaded Surface Display

1) MPR

What processing technique was used to create the following image? 1) MPR 2) Volume Rendering 3) MIP 4) Shaded Surface Display

3) Lung algorithm

What reconstruction algorithm is best suited for demonstrating the lung tissue? 1) Bone algorithm 2) Standard algorithm 3) Lung algorithm 4) Cerebral algorithm

2) 2.5 mm

What reconstruction slice thickness is generally used for axial images of a CTA chest protocol? 1) 1.25 mm 2) 2.5 mm 3) 5 mm 4) <1.25 mm

1) 30 seconds

What scan delay time is appropriate for viewing the renal arteries? 1) 30 seconds 2) 60 seconds 3) 90 seconds 4) 5 minutes

4) 5 minutes

What scan delay time should be used to evaluate the urinary collecting system? 1) 30 seconds 2) 60 seconds 3) 90 seconds 4) 5 minutes

3) 60 seconds

What scan delay time was used to acquire this image of the adrenal glands? 1) Non-contrast 2) 30 seconds 3) 60 seconds 4) 4 minutes

1) CT abdomen pelvis W

What scanning protocol should initially be used to evaluate nausea and diarrhea with an unknown origin? 1) CT abdomen pelvis W 2) CTA abdomen pelvis 3) CT multiphase pancreas 4) CT multiphase liver

2) 2.5 mm

What slice parameter is used for imaging the liver in multiple phases of contrast? 1) 1.0 mm 2) 2.5 mm 3) 5.0 mm 4) 10.0 mm

1) Cervical

What spinal level is demonstrated in this image? 1) Cervical 2) Thoracic 3) Lumbar 4) Sacral

2) 150 ml at 4 ml/s 3) 100 ml at 4 ml/s

What two IV contrast injection techniques should be used to evaluate a patient for PE? (Select two) 1) 100 ml at 3 ml/s 2) 150 ml at 4 ml/s 3) 100 ml at 4 ml/s 4) 150 ml at 3 ml/s

1) Inspiration 3) Expiration

What two phases of respiration should be used for evaluation of interstitial lung disease? (Select two) 1) Inspiration 2) Light breathing 3) Expiration

1) Iodine

What type of IV contrast is traditionally used for imaging the abdomen and pelvis? 1) Iodine 2) Barium 3) Water

1) No contrast is visible

What type of contrast was administered to this patient prior to scanning? 1) No contrast is visible 2) Oral contrast 3) Rectal contrast 4) Intravenous contrast

1) 500 ml

What volume of oral contrast is generally appropriate for routine imaging of the abdomen pelvis? 1) 500 ml 2) 5 ml 3) 50 ml 4) 5,000 ml

1) 400 WW and 40 WL

What windowing technique is traditionally used for viewing the soft tissues of the abdomen following CTA imaging? 1) 400 WW and 40 WL 2) 80 WW and 30 WL 3) 1800 WW and -600 WL 4) 2500 WW and 600 WL

1) 2500 WW and 600 WL

What windowing technique was used for this image of the facial bones? 1) 2500 WW and 600 WL 2) 600 WW and 2500 WL 3) 400 WW and 40 WL 4) 80 WW and 30 WL

1) 350 WW and 30 WL

What windowing technique would be appropriate for viewing the soft tissues of the abdomen? 1) 350 WW and 30 WL 2) 80 WW and 30 WL 3) 1400 WW and 400 WL 4) 2500 WL and -400 WL

Uniformity

When a uniform object is imaged, each pixel should have the same value

1) Immediately prior to scanning

When should oral contrast be administered to demonstrate filling in the stomach and duodenum? 1) Immediately prior to scanning 2) 50 minutes prior to scanning 3) 5 minutes prior to scanning 4) 5 hours prior to scanning

1) Ascending Aorta

Where should bolus-tracking ROI be placed for CTA imaging of the coronary arteries? 1) Ascending aorta 2) Descending aorta 3) Left ventricle 4) Right atrium

1) 1.25 mm slice thickness and 0.625 mm slice interval

Which axial data set should be used for creating sagittal reformations of the lumbar spine? 1) 1.25 mm slice thickness and 0.625 mm slice interval 2) 5.0 mm slice thickness and 5.0 mm slice interval 3) 2.5 mm slice thickness and 2.5 mm slice interval 4) 3.75 mm slice thickness and 3.75 mm slice interval

3) 0.625 mm slices in the standard algorithm

Which image series will produce the best volume-rendered (3D) models of the bones of the wrist? 1) 0.625 mm slices in the bone algorithm 2) 2.5 slices in the bone algorithm 3) 0.625 mm slices in the standard algorithm

2) CT ankle WO

Which imaging protocol is appropriate for assessing a fracture of the distal tibia? 1) CT wrist WO and W 2) CT ankle WO 3) CT knee W 4) Wrist WO

1) 2500 WW and 600 WL

Which of the following imaging windows would best visualize fractures of the cranium and facial bones? 1) 2500 WW and 600 WL 2) 400 WL and 600 WL 3) 80 WW and 40 WL 4) 400 WW and 40 WL

4) Reduce patient radiation exposure

Which of the following is NOT a common reason to use contrast enhancement during CT scanning? 1) Differentiate between normal tissues 2) Differentiate between normal tissues and abnormalities 3) Add visual contrast to the images 4) Reduce patient radiation exposure

1) Hormone changes

Which of the following is a reason to perform multiphase CT imaging of the adrenal glands? 1) Hormone changes 2) Hematuria 3) Bilateral flank pain 4) Increase WBC count

3) 5 mm

Which of the following is an appropriate slice thickness for viewing axial images of the routine venous phase chest CT? 1) 1.25 mm 2) 2.5 mm 3) 5 mm 4) <1.25 mm

2) Pediatric scanning

Which of the following is potential reason to decrease the IV contrast volume used during a CT scan? 1) Angiographic scanning 2) Pediatric scanning 3) Slow scanner speed 4) Long scan length

4) Gall bladder

Which of the following organs does not necessarily need to be included in a CT scan performed to evaluate a patient for renal stones 1) Kidneys 2) Ureters 3) Urinary bladder 4) Gallbladder

3) Image C

Which of the following scout images properly demonstrates the scan localizer for a CT adrenal scan? 1) Image A 2) Image B 3) Image C 4) Image D

1) Image A

Which of the following scout images properly demonstrates the scan localizer for a routine CT scan of the abdomen pelvis? 1) Image A 2) Image B 3) Image C 4) Image D

4) 2.0 mm thickness x 2.0 mm interval

Which of the following slice parameters is appropriate for viewing axial slices through the elbow? 1) 0.5 mm thickness x 0.5 mm interval 2) 0.5 mm thickness x 0.25 mm interval 3) 1.0 mm thickness x 5.0 mm interval 4) 2.0 mm thickness x 2.0 mm interval

2) Nephrons

Which of thes renal structures are maximally enhanced between 60 and 90 seconds after IV contrast injection? 1) Renal arteries 2) Nephrons 3) Renal pelvis 4) Renal cortex

1) Bolus tracking in abdominal aorta

Which of these IV contrast enhancement protocols should be used for imaging the abdominal aorta? 1) Bolus tracking in abdominal aorta 2) Bolus tracking in the ascending aorta 3) 60 second scan delay time 4) 90 scan delay time

1) 150 ml at 4 ml/s

Which of these IV contrast injection parameters are suitable for imaging of the coronary arteries? 1) 150 ml at 4 ml/s 2) 150 ml at 2.5 ml/s 3) 90 ml at 4 ml/s 4) 100 ml at 3 ml/s

1) 150 ml at 4 ml/s

Which of these IV contrast protocols is appropriate for CTA imaging of the coronary arteries? 1) 150 ml at 4 ml/s 2) 150 ml at 2.5 ml/s 3) 90 ml at 4 ml/s 4) 100 ml at 3 ml/s

1) Soft tissue

Which of these algorithms is used for angiographic imaging of the abdomen and pelvis? 1) Soft tissue 2) Bone 3) Lung 4) Edge-enhancing

1) Renal calculi

Which of these conditions are best evaluated without the use of IV contrast? 1) Renal calculi 2) Renal cell carcinoma 3) Transitional cell carcinoma 4) Renal mass of known etiology

1) Burst fracture of L4

Which of these conditions are best visualized with routine CT imaging of the lumbar spine WO contrast? 1) Burst fracture of L4 2) Spina bifida at the level of L1 3) Spinal stenosis at the level of L3 4) Spinal metastasis in L2 and L3

1) 30 second scan delay time

Which of these contrast enhancement protocols should be used to evaluate a mediastinal tumor? 1) 30 second scan delay time 2) Bolus tracking in the pulmonary arteries 3) Bolus tracking in the ascending aorta 4) Non-contrast

1) Bolus tracking in the aortic arch

Which of these contrast enhancement timing methods would be appropriate for imaging the Circle of Willis? 1) Bolus tracking in the aortic arch 2) Bolus tracking in the jugular vein 3) 45 second scan delay time 4) 60 second scan delay time

1) 0.5 mm thickness x 0.5 mm interval

Which of these data sets should be used as the source images for creating reformations through the ankle? 1) 0.5 mm thickness x 0.5 mm interval 2) 0.7 mm thickness x 0.5 mm interval 3) 1.0 mm thickness x 5.0 mm interval 4) 2.0 mm thickness x 2.0 mm interval

2) Retrospective gating

Which of these gating techniques require that scan data be acquired for all phases of cardiac contraction and relaxation? 1) Prospective gating 2) Retrospective gating 3) Both perspective and retrospective gating

2) Sagittal

Which of these imaging planes is commonly used to visualize the full extent of the aortic arch and the entirety of the thoracic aorta? 1) Axial 2) Sagittal 3) Coronal 4) Oblique

4) CT high resolution chest

Which of these imaging protocols allow for large gaps between reconstructed slices? 1) CTA chest of the thoracic aorta 2) CTA chest for PE 3) CT chest in venous phase 4) CT high resolution chest

1) 150 ml at 4 ml/s

Which of these intravenous contrast protocols would provide the best arterial enhancement during a CTA runoff procedure? 1) 150 ml at 4 ml/s 2) 150 ml at 2.5 ml/s 3) 90 ml at 4 ml/s 4) 100 ml at 3 ml/s

1) Metoclopramide

Which of these medications may be administered to stimulate emptying of the stomach in preparation of the CT enterography study? 1) Metoclopramide 2) Glucagon 3) Nitroglycerin 4) Beta blocker

4) CTA runoff

Which of these protocols demonstrates arterial structures from the diaphragm through the ankles? 1) CTA for pulmonary embolism 2) CTA thoracic aorta 3) CT abdomen and pelvis with contrast 4) CTA runoff

2) CTA chest for PE

Which of these protocols will best demonstrate stenosis of the pulmonary arteries? 1) CTA chest of the thoracic aorta 2) CTA chest for pulmonary embolism 3) CT chest in venous phase 4) CT high resolution chest

1) 2.5 mm slices in a softening algorithm

Which of these reconstruction parameters is suitable for multiphase imaging of the pancreas? 1) 2.5 mm slices in a softening algorithm 2) 5.0 mm slices in softening algorithm 3) 2.5 mm slices in a sharpening algorithm 4) 5.0 mm slices in a sharpening algorithm

1) 1.0 mm slice thickness and 1.0 slice interval

Which of these reconstruction parameters would be most appropriate for CT imaging of the cervical spine WO? 1) 1.0 mm slice thickness and 1.0 slice interval 2) 2.0 mm slice thickness and 2.0 slice interval 3) 1.0 mm slice thickness and 2.0 slice interval 4) 3.0 mm slice thickness and 3.0 slice interval

1) 1.0 mm slice thickness and 1.0 slice interval

Which of these reconstruction parameters would be most appropriate for CT imaging of the lumbar spine following the myelogram protocol? 1) 1.0 mm slice thickness and 1.0 slice interval 2) 3.0 mm slice thickness and 3.0 slice interval 3) 1.0 mm slice thickness and 2.0 slice interval 4) 3.0 mm slice thickness and 1.5 slice interval

4) 5.0 mm slices in the standard algorithm

Which of these reconstruction slice parameters will produce images with the least amount of image noise in the brain? 1) 2.5 mm slices in the bone algorithm 2) 2.5 mm slices in the standard algorithm 3) 5.0 mm slices in the bone algorithm 4) 5.0 mm slices in the standard algorithm

2) CT venogram head

Which of these scans must be performed from superior to inferior? 1) CT head WO 2) CT venogram head 3) CTA head 4) CTA head and neck

3) Image C

Which of these scout images demonstrates an 18 cm display FOV? 1) Image A 2) Image B 3) Image C 4) Image D

1) 2.5 mm slices with matching slice interval

Which of these slice parameters are preferred for visualization of the posterior fossa of the cranium? 1) 2.5 mm slices with matching slice interval 2) 2.5 mm slices with 5 mm interval 3) 5 mm slices with 2.5 mm interval 4) 5 mm slices with matching interval

1) 1.25 mm

Which of these slice parameters should be used to create multiplanar reformations of the abdomen and pelvis? 1) 1.25 mm 2) 2.5 mm 3) 5 mm 4) >5 mm

1) Renal arteries

Which of these structures will demonstrate the highest level of contrast enhancement at a 25 second scan delay time? 1) Renal arteries 2) Nephrons 3) Renal pelvis 4) Renal veins

4) CT urogram

Which of these studies is most useful for mapping the collecting system prior to ureter stent placement? 1) CT renal stone 2) CT kidney protocol 3) CT adrenal protocol 4) CT urogram protocol

4) CT urogram

Which of these studies is most useful in identifying the cause of recurrent renal stones? 1) CT renal stone 2) CT kidney 3) CT adrenal 4) CT urogram

1) Central lines (Port)

Which of these venous access devices are sometimes labeled for CT power injection? 1) Central lines (Port) 2) Dialysis catheters 3) Jugular lines

1) 400 WW and 40 WL

Which of these windowing techniques is appropriate for viewing the arteries of a CTA head examination? 1) 400 WW and 40 WL 2) 80 WW and 40 WL 3) 2500 WW and 600 WL 4) 1500 WW and -400 WL

1) 400 WW and 40 WL

Which of these windowing techniques is appropriate for viewing the intervertebral disc following routine CT imaging of the spine? 1) 400 WW and 40 WL 2) 80 WW and 40 WL 3) 2500 WW and 600 WL 4) 1500 WW and -400 WL

4) Non-contrast

Which phase of IV contrast enhancement is ideal for initial imaging of intracranial hemorrhage? 1) Venous phase 2) Arterial phase 3) Delayed phase 4) Non-contrast

1) Portal venous phase

Which phase of contrast enhancement in the abdomen peaks at 50-60 seconds after initiating IV injection? 1) Portal venous phase 2) Arterial phase 3) Delayed phase 4) Capillary phase

1) Maxillary Mass 2) Diffuse Swelling 3) Dental Abscess

Which three of the following is an appropriate indication for CT imaging of the facial bones? (Select three) 1) Maxillary Mass 2) Diffuse Swelling 3) Dental Abscess 4) Subarachnoid Hemorrhage

2) Test bolus 3) Bolus tracking

Which two contrast injection methods are useful for precisely timed angiographic procedures? (Select two) 1) Scan delay time 2) Test bolus 3) Bolus tracking 4) Fixed time delay

1) Sagittal reformation of the full scan 2) Coronal reformation of full scan

Which two of these reformation series are typically created with CT imaging of the thoracic spine WO contrast? (Select two) 1) Sagittal reformations of the full scan 2) Coronal reformation of the full scan 3) Axial reformations on the disc spaces

1) 400 WW and 40 WL

While viewing high-resolution images of the lungs, the radiologists notices a suspicious mass in the mediastinum. What window presentation will she use to view the mass? 1) 400 WW and 40 WL 2) 2500 WW and 600 WL 3) 1800 WW and -600 WL 4) 80 WW and 30 WL

Electron return effect

With a magnetic field (ie MRI Linac), the secondary electrons can be deflected /curved --> asymmetric dose distribution laterally

Noise

a variation in CT numbers above or below the average value. Appears as grainy

Contrast resolution

ability to distinguish one soft tissue from another without regard to the size or shape

Temporal resolution

ability to freeze or decrease motion in a scanned object. Important for 4DCT

Rank in order of lowest to highest HU: Air, fat, water, soft tissue, bone

air (-1000) < fat (-100) < water (0) < soft tissue (100-300) < bone (200 - 3000)

A CBCT has (worse/better) resolution than regular diagnostic multiple slide CT in the cephalo-caudal direction

better

To reduce CT imaging cupping artifacts from beam hardening, use a ___

bowtie filter

ring artifact

caused by a bad detector

Starring artifact

caused by metal materials

Streak Artifact

caused by motion

Window width relates to

contrast

3 Steps of CT image formation

data acquisition, image reconstruction, and image display

window level relates to

density

For planar imaging, imaging resolution depends on ___

detector spacing (mm/pixel)

Partial volume effect

different tissue densities within the voxel, giving an "odd" linear attenuation coefficient

DRR

digitally reconstructed radiograph that is generated from the CT, in kV *Gold standard*

To increase signal to noise ratio (SNR) for CT imaging, you need to increase:

dose (MU or mAs) less noise --> better image

What is the CT number (Hounsfield units = HU) used to estimate?

electron density Remember: for MV photon beams, Compton interactions dominate

What causes ring artifact in third gen CT scanners?

faulty detectors or inaccurate detector calibration

For a full-fan CBCT, use a __ bowtie filter. When would you use a full fan CBCT?

full bowtie filter for full-fan CBCT Use full-fan CBCT if single FOV can fit within 24 cm

For a half-fan CBCT, use a __ bowtie filter. When would you use a half fan CBCT?

half bowtie filter for half-fan CBCT If FOV > 24 cm use half-fan CBCT

Per TG-142, what image system needs yearly QA?

imaging dose

To decrease the CT image noise, what dose parameter do you need to change?

increase mAs (tube current [mA] x exposure time [s])

CT image noise decrease as dose ___(dec/inc)

increases It is compromise.

Increasing pitch

increases the volume of tissue that can be imaged in one 360 degree rotation

Relationship between window width and contrast

indirect

To increase image contrast, you need to decrease:

kVp lower kVp --> higher contrast Higher kVp --> lower contrast Note: Increasing the mAs will increase SNR but has not effect on contrast

Advantages to using MV for CT imaging in IGRT

less artifact of bone/metal In kV CT, photo-electric effect dominates, which is governed by Z^3

The wider the window, the (less/more) small differences in HU you will appreciate in a CT image.

less small difference

For CT imaging, what does the level, width, and range tell you?

level: minute differences width (of the window): the magnitude of the HU spectrum Range = level +/- width / 2 where the window is on the spectrum of HU

What are 2 limitations of CT?

limited soft tissue contrast anatomic in nature (no functional info)

Wide window width

low contrast

Use of a dual energy CT scanner for proton beam treatment planning has the advantage(s) over a single-energy CT scanner because of____

more accurate determination of proton beam range in patient * range uncertainty is biggest concern in proton therapy, so determination of different substances is important to determine stopping power and therefore proton range

Pitch

ratio of the distance the table advances per gantry rotation

Beam pitch

ratio of the table advance to the beam thickness

For 3D imaging, imaging resolution depends on ___

scanning parameter and reconstruction Longitudinal direction: slice thickness (2-5mm) Axial direction: Field of view/# pixels

Why is the cone beam CT image quality not as good as a fan-beam CT?

scattering (cone of xrays instead of a fan)

CBCT has better resolution in ___ direction than diagnostic CT

sup/inf because you can get slice thickness of 0.22mm/pixel (conventional CT is 1mm)

For CT scanners, define pitch

table travel per rotation / slice thickness

CT number (Hounsfield units = HU) for water is ___ CT number (Hounsfield units = HU) for air is ___

water: 0 air: -1000