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CT Cross Training > ASRT EXAM 5 > Flashcards

ASRT EXAM 5 Flashcards

1
Q

Which of the following best represents typical bone window settings?
A. WW 100; WL 30.
B. WW 350; WL 50.
C. WW 1500; WL -600.
D. WW 1800; WL 400

A

D. WW 1800; WL 400.

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2
Q

Which of the following changes would improve a CT scan’s signal-to-noise ratio (SNR) and reduce image noice?
A. Increasing pitch.
B. Decreasing mA.
C. Applying a high spatial frequency algorithm.
D. Using a larger voxel dimension.

A

D - Using a larger voxel dimension.

Using a larger voxel dimension would improve a CT scan’s signal-to-noise ratio (SNR) and reduce image noice b/c of the greater amount of photon flux.

Voxel dimensions are increased by using a larger DFOV, wider slice thickness, or decreasing the matrix size.

An increase in image noise would occur with a lower mA setting, increased pitch, or high spatial frequency algorithm.

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3
Q

Which term is used to describe the amount of variation inside a region of interest (ROI)?
A. Resolution.
B. Standard deviation.
C. Linearity.
D. Matrix size.

A

B - Standard deviation.

Standard deviation is used to describe the amount of variation inside a region of interest (ROI).
Low standard deviation indicates that the ROI has little variation, while higher values indicate high variance.
Standard deviation is influenced by the presence of streak artifacts, mixed attenuation tissues, & incorrect ROI margins.

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4
Q

All of the following methods would reduce the radiation dose for a pediatric patient during a CT procedure, EXCEPT:
A. Using a multiphase scanning approach.
B. Scanning only the indicated area.
C. Increasing pitch.
D. Reducing mAs.

A

A - Using a multiphase scanning approach.

(Increasing pitch = makes table move faster through gantry = decreased time = decreased patient dose).

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5
Q

Relationship between Pitch & Pt Dose.

A

Increasing pitch = table moves faster through gantry = more anatomy scanned in a set amount of time = reduce pt dose.

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6
Q

What anatomy is best demonstrated during a CT scan of the larynx when a patient pronates a continuous “EEE” sound during the entire scan acquisition?

A

Vocal Chords.

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7
Q

What setting controls the energy of the X-rays emitted at the focal spot on the anode?

A

KVp.

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8
Q

The kinetic energy conversion produces approximately ________% electromagnetic energy in the form of X-ray and __________% thermal energy.

A

1% electromagnetic energy & 99% thermal energy.

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9
Q

All of the following are true when providing care for a patient with a chest tube, EXCEPT:
A. The chest tube should remain unclamped.
B. The drainage system can be raised above the pts chest.
C. Chest tubing should remain as straight as possible without kinks.
D. Continuous bubbling of the water seal may indicate a leak.

A

B - The drainage system can be raised above the pts chest.

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10
Q

When using a bow tie filter, which of the following is critical to AVOICD undesired irregularities in a pts radiation dose?
A. Correct WW and WL settings.
B. Centering the pt in the gantry.
C. Choosing a suitable post-processing technique.
D. Selecting the appropriate DFOV.

A

B - Centering the pt in the gantry.

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11
Q

What is a bowtie filter?

A

A bowtie or shaping filter can counterbalance the non-columnar quality of most pt body forms. It adds extra filtration along the side of the beam to absorb X-rays, which helps to reduce pt dose. It is critical to center the pt in the middle of the gantry when using a bowtie filter to prevent radiation dose irregularities.

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12
Q

Which of the following is a universally adopted file format that allows the exchange of medical images between facilities?
A. PACS.
B. HL-7.
C. DICOM.
D. EMR.

A

C - DICOM.

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13
Q

The reference artery for post-processing of a ct brain perfusion should:

A

Be visible in a cross-section.

When performing the post-processing for a CT brain perfusion, it is important to select a reference artery seen in a cross-section. Additionally, the reference artery should be one of the first to enhance & produce a curve with a wide width & high enhancement peak.

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14
Q

The imaging plane used parallel to the foot’s metatarsals is the:
A. Sagittal plane.
B. Oblique axial plane.
C. Coronal plane.
D. Direct axial plane.

A

B - oblique axial plane.

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15
Q

A typical injection rate for a CT abdomen and pelvis with contrast for cancer staging is:
A. 1 mL/s.
B. 3 mL/s.
C. 5 mL/s.
D. 12 mL/s.

A

B - 3 mL/s.

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16
Q

When performing a cat scan of the orbits in the axial plane, images should be acquired parallel to the:

A

Infraorbital meatal line (IOML) in thin sections of 1 to 3 mm.

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17
Q

The most proximal main branch of the right coronary artery (RCA) is the:

A

Conus artery.

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18
Q

A typical injection flow rate for CTA of the chest to evaluate for pulmonary embolism is:

A

4 to 5 mL/s.

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19
Q

During cardiac CT, a complete cardiac cycle is measured by the:

A

R-R interval. (It represents one cardiac cycle on a ECG).

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20
Q

All of the following are considered central venous catheters, EXCEPT:
A. Peripherally inserted central catheter (PICC).
B. Hickman.
C. Grohsong.
D. Levin.

A

D - Levin.

Levin is a type of plastic nasogastric tube that has a single-lumen and holes near the tip. It is passed through a patients nose & into the stomach and is commonly used for gastric decompression.

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21
Q

The CT scanner function that adjusts tube current based on signal-to-noise ratio (SNR) to maintain a constant signal & reduce patient dose is referred to as:

A

Automatic tube current modulation.

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22
Q

Which of the following techniques should NOT be used when performing a CTA of the abdomen to rule-out an aortic dissection?
A. Use a test bolus or automated bolus tracking to scan during the arterial phase.
B. Have the patient ingest barium sulfate.
C. Inject contrast media at a flow rate of 4 to 5 mL/s.
D. Employee a single-breath hold during the scan.

A

B - Have the patient ingest barium sulfate.

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23
Q

The unit of measurement for exposure which describes the ability of X-rays to ionize a volume of air is:

A

Roentgen (R).

The roentgen (R) is a unit of measurement that describes the quantity of radiation absorbed in a volume of air. The SI unit for exposure is C/kg.

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24
Q

What is a Roentgen (R) and its SI units.

A

The roentgen (R) is a unit of measurement that describes the quantity of radiation absorbed in a volume of air. The SI unit for exposure is C/kg.

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25
Q

What 3D post-processing technique generates an image by including gall voxels?
A. Surface rendering.
B. MinIP.
C. MIP.
D. Volume rendering.

A

D - Volume rendering.

Volume rendering (VR) is a 3D post-processing technique that includes all voxels to generate an image, which demonstrates relationships between/t various anatomical structures.
- a benefit of VR post-processing is that items such as color scale, window setting, and values can be altered.

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26
Q

What is a typical injection rate for a CTA head to evaluate the circle of Willis?

A

4.0 mL/s.

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27
Q

What pathological condition involves the accumulation of excess fluid inside the lungs due to obstruction of the pulmonary circulation?

A

Pulmonary edema.

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28
Q

What step of imaging collects and measures the number of transmitted X-rays that strike the CT detectors?

A

Data acquisition.

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29
Q

Which of the following would affect the arrival time of IV contrast media at the main pulmonary artery during a CTA chest?
A. The pts cardiac output.
B. The pts gender.
C. The generation of CT scanner.
D. The pitch setting.

A

A - the pts cardiac output.

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30
Q

What type of artifacts is typically caused by a faulty detector in the CT system?

A

Ring.

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31
Q

The process that removes image blur from reconstructed images by including data obtained from X-ray tube rotations slightly above & below a slice is called:

A

Interpolation.

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32
Q

__________ allows the pt to travel through the CT gantry in one single breath-hold while the X-ray tube continuously rotates.

A

Helical mode.

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33
Q

On a 64-slice MDCT system with beam pitch set to 1.75 and a total collimation of 20 mm, how far will the table move per gantry rotation?

A

35 mm.

On MDCT scanner: beam pitch = table feed per rotation / total collimation [total number of sections x section width].

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34
Q

To optimally display opacification of the renal collecting system, the scan delay should be set to:
A. 20 to 25 seconds.
B. 30 to 40 seconds.
C. 70 to 90 seconds.
D. 3 to 15 minutes.

A

D 3 to 15 minutes.

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35
Q

The amount of blood (mL) that moves through 100 g of brain issue every minute is the:

A

Cerebral blood flow (CBF).

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36
Q

The amount of blood (mL) found within 100 g-volume of brain tissue is the:

A

Cerebral blood volume (CBV).

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37
Q

The average time for blood to travel through a given area of brain tissue & is measured in seconds is the:

A

Mean transit time (MTT).

38
Q

The central volume principle is a relation between what?

A

CBF, CBV, & MTT
(Brain blood flow, brain volume, and means transit time)

CBF = CBV/MTT).

39
Q

The entire gestation dose limit for a fetus is:

A

5.0 mSv.

40
Q

If a pixel dimension is 0.5 mm and the matrix size is 512x512, what is the size of the DFOV in cm?

A

25.6 cm.

Formula: d = FOV (mm) / Matrix.
(0.5 mm = x/512).
In this case , x is equal to 256 mm, which is converted to 25.6 cm.

41
Q

All of the following are typical series included in a HRCT of the chest except:
A. Supine chest images with inspiration.
B. Right lateral images with expiration.
C. Prone chest images with inspiration.
D. Supine chest images with expiration.

A

B - Right lateral images with expiration.

42
Q

What does a typical HRCT chest include?

A

Includes three images:
- Supine with inspiration.
- Supine with expiration.
- Prone with inspiration.

43
Q

The normal range of respiration for an adult at rest is:

A

12-20 breaths/min.

44
Q

_________ is a defect in the pars interarticularis.

A

Spondyloysis.

45
Q

An adaptive array detector system is configured with:

A

The thinnest detectors in the center & increasingly wider detectors along the z-axis.

46
Q

What parameter primarily controls the depth of a voxel?
A. Sector width.
B. SFOV.
C. Matrix size.
D. DFOV.

A

A - Sector width.

47
Q

Which of the following CT procedures would be most suitable to evaluate polyps in the large intestine?
A. CT-guided aspiration.
B. CT enteroclysis.
C. CT enterography.
D. CT colonography.

A

D - CT colonography.

48
Q

The main factor of IV contrast media that causes adverse side effects is the:

A

Osmolality.

49
Q

For a manual coronal Multiplanar reformation (MPR) created from a sagittal MPR of a scapula, the oblique sagittal MPR should be parallel to the:

A

Body of the scapula.

50
Q

During CT urography, the delay for excretory phase imaging is:

A

3-16 minutes.

51
Q

Which of the following conditions is evaluated using a noncontrast CT abdomen and pelvis exam?
A. Hemangioma.
B. Urinary tract calculi.
C. Adrenal mass.
D. Aortic dissection.

A

B - Urinary Tract Calculi.

52
Q

Which of the following contrast media can cause peritonitis if it leaks into the abdominal cavity?
A. Barium sulfate suspension.
B. LOCM.
C. HOCM.
D. Water-soluble contrast.

A

A - Barium sulfate suspension.

53
Q

What 3D post-processing techniques uses approximately 10% of the available data to create an image from pixel values over a predetermined threshold value?

A

Surface rendering.

54
Q

What phase of liver enhancement is optimal for the evaluation of hyper vascular lesions or tumors such as hepatocellular carcinoma (HCC)?

A

Arterial phase.

55
Q

The typical anatomic scan range for a CT abdomen with contrast to evaluate the pancreas is from:

A

Just above the diaphragm through the iliac crest.

56
Q

Which of the following SFOV sizes would be the most suitable for a CT of the pelvis on an adult pt with a hypersthenic body habits?
A. Half-field.
B. Small (25 cm).
C. Medium (35 cm).
D. Large (42-50 cm).

A

D. Large (42-50 cm).

57
Q

The area within the gantry from which raw data is acquired is called the:

A

Scan field of view (SFOV).

58
Q

All of the following are typically included in a comprehensive CT stroke protocol, EXCEPT:
A. CT of the temporal bones.
B. CT perfusion of the brain.
C. CTA of the brain and carotids.
D. CT head without contrast.

A

A. CT of the temporal bones.

59
Q

During a contrast exam, which of the following anatomical structures would most benefit from MIP post-processing?
A. Lungs.
B. Biliary tree.
C. Trachea.
D. Aorta.

A

D - Aorta.

60
Q

Which of the following dose measurements requires no overlap or gaps between slices?
A. Gy.
B. DLP.
C. MSAD.
D. CTDI.

A

D. CTDI.

Computer tomography dose index (CTDI) requires that slices be adjacent & contain no gaps or overlap to calculate. If CT scans have more complex parameters, other indices may be used such as CTDI100 or CTDIvol.

61
Q

A post-patient collimator is used to:

A

Reduce the amount of scatter radiation reaching the detectors.

62
Q

Which of the following is used to create a new CT image using retrospective reconstruction?
A. Image data.
B. Dose maps.
C. Raw Data.
D. WW and WL.

A

C. Raw Data.

63
Q

Which of the following protocols would be most suitable for optimal Opacification of the stomach & duodenum?
A. Drink an additional amount of contrast 30 minutes before the scan.
B. Ingest all contrast 120 minutes before the scan.
C. Swallow an additional amount of contrast immediately before scanning.
D. Use both oral & rectal contrast.

A

C. Swallow an additional amount of contrast immediately before scanning.

64
Q

Which of the following will help optimally visualize the bladder on a CT scan?
A. Perform the CT with no contrast.
B. Position the patient prone.
C. Scan the bladder when full of urine or contrast.
D. Administer rectal contrast.

A

C. Scan the bladder when full of urine or contrast.

65
Q

The CT scan of the _________ is performed to evaluate for a possible fracture of the acetabulum.

A

Hip.

66
Q

One of the main purposes of filtration in the x-ray beam is to:
A. Decrease detector efficiency.
B. Remove low energy x-rays from the beam.
C. Increase the number of x-rays reaching the patient.
D. Reduce occupational dose.

A

B. Remove low energy x-rays from the beam.

67
Q

All of the following are useful when providing pt education, EXCEPT:
A. Explaining the various steps of the procedure.
B. Describing expected side effects of medications or contrast media.
C. Stating the estimated duration of the procedure.
D. Providing false reassurances to ease pt fears.

A

D. Providing false reassurances to ease pt fears.

68
Q

The normal range for an adult pt’s pulse is:

A

60 to 100 beats per minute (BPM).

69
Q

The normal range for an child’s and infant heart rate.

A

Child: 95 to 100 BPM.
Infant: 100 to 160 BPM.

70
Q

Which of the following is an example of a late stochastic effect?
A. Cataractogenesis.
B. Epilation.
C. Carcinogenesis.
D. Erythema.

A

C. Carcinogenesis.

Late stochastic effects, such as cancer or genetic anomalies, are nonthreshold and occur randomly. Nonstochastic effects are deterministic and affected directly by radiation dose. Early nonstochastic effects include erythema and epilation. An example of a late nonstochastic effect is cataractogenesis

71
Q

Late vs. Early Stochastic effects.

A

Late stochastic effects, such as cancer or genetic anomalies, are nonthreshold and occur randomly. Nonstochastic effects are deterministic and affected directly by radiation dose. Early nonstochastic effects include erythema and epilation. An example of a late nonstochastic effect is cataractogenesis

72
Q

To reduce the risk of step artifacts on CT images:
A. Increase the kVp.
B. Adjust the WW and WL settings.
C. Use overlapping, thin sections.
D. Reduce scan time.

A

C. Use overlapping, thin sections.
- Using overlapping, thin sections of images will reduce the risk of step artifacts on CT images. Step artifacts will appear as a deficiency of general sharpness and detail on CT images. This type of artifact was common in older CT systems.

73
Q

The _________ pull the large intestine into pouches or haustra.

A

Taeniae coli.

74
Q

When preparing a pt for a CT biopsy, the skin is prepped by scrubbing from:

A

The center, working OUTWARD.

75
Q

All of the following are included in CT imaging of the airways, EXCEPT:
A. fast scan Aquisition with a single-breath hold.
B. an inspiration & expiration series.
C. Injection of IV contrast media.
D. image reconstruction of thin overlapping slice sections.

A

C. Injection of IV contrast media.

76
Q

What x-ray interaction with matter is responsible for a MAJORITY of the pts radiation dose?

A

Photoelectric.

Photoelectric absorptions are responsible for a majority of the patient’s radiation dose. In these cases, the incoming x-ray’s energy is fully absorbed by an atom’s inner-shell, which ejects an electron. An electron from a higher-shell will drop down to fill the void and emit a secondary characteristic x-ray. In particular, tissues with high atomic number will undergo a higher proportion of photoelectric interactions.

77
Q

Photoelectric Interactions

A

Photoelectric absorptions are responsible for a majority of the patient’s radiation dose. In these cases, the incoming x-ray’s energy is fully absorbed by an atom’s inner-shell, which ejects an electron. An electron from a higher-shell will drop down to fill the void and emit a secondary characteristic x-ray. In particular, tissues with high atomic number will undergo a higher proportion of photoelectric interactions.

78
Q

_________ enables the x-ray tube to rotate continuously while the pt travels through the gantry during a CT scan.

A

Slip-ring technology.

79
Q

What special precaution is needed for pts on Coumadin (warfarin) during contrast imaging procedures?

A

Pressure should be applied to the IV site after removal of the catheter.
(Warfarin = helps reduce blood clots & makes pts bruise easier!).

80
Q

When performing an axial scan, the multiple scan average dose (MSAD) calculation should incoporate:

A

Image spacing.

81
Q

What is the purpose of administering a B-blocker during a CT cardiac study?

A

Lowers the pt’s heart rate.

82
Q

Which of the following cell types is the most radiosensitive?
A. Nerve cells.
B. Reproductive cells.
C. Brain cells.
D. Muscle cells.

A

B. Reproductive cells.

83
Q

For a CT soft tissue neck:
A. the pt is positioned supine with both arms raised above their head.
B. a slice thickness of 10mm is reconstructed.
C. the DFOV is set between 18 and 25 cm.
D. a WW of 1500 and a WL of -700 WL are applied.

A

C.

84
Q

All of the following are desirable characteristics or qualities of CT detectors, EXCEPT:
A. high dynamic range.
B. rapid signal decay.
C. afterglow.
D. increased efficiency.

A

C. Afterglow.

85
Q

What medication is used to constrict blood vessels and stimulate the heart during cardiac arrest & severe allergic reactions?

A

Epinephrine.

86
Q

A CT of the cspine with IV contrast is ordered to evaluate for injury to the vertebral arteries. The scan acquisition should occur in the _____ phase.

A

Arterial phase.

87
Q

Which of the following is a suitable method to reduce metallic artifacts on a CT image?
A. decrease kVp setting.
B. increase WW.
C. use thick section slices.
D. decrease mA.

A

B. Increase WW.

88
Q

Which of the following body tissues has the highest linear attenuation coefficient?
A. fat.
B. blood.
C. bone.
D. muscle.

A

C. bone.

89
Q

The term that describes the accuracy b/t CT numbers & corresponding linear attenuation coefficient is:

A

Linearity.

90
Q

After injection of intrathecal contrast, the pt should:

A

rest 4 to 8 hours with the head of the bed elevated 35 to 45 degrees.

91
Q

When performing pediatric CT scans, what is the most common dose formula for IV contrast media?

A

2 mL/kg.

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