Question 1

The minimum distance between two objects that allows them to be seen as separate and distinct would define what CT imaging parameter?&#10;A)Low-contrast resolution&#10;B)Uniformity&#10;C)High-contrast resolution&#10;D)Image noise

Accepted Answer

The minimum distance between two objects that allows them to be seen as separate and distinct is a measure of high-contrast resolution in CT imaging. Low-contrast resolution refers to the ability to distinguish small differences in contrast between tissues, uniformity refers to the consistency of image quality across the entire image, and image noise refers to the presence of random variations in image intensity.

Question 2

The laser light field and radiation field should coincide to within ____ mm.&#10;A)0.5&#10;B)1.0&#10;C)2.0&#10;D)5.0

Accepted Answer

For optimal performance, the light field should coincide with the radiation field to within 2 mm.

Question 3

For ACR CT accreditation, the Water CT Number and Standard Deviation (Noise) should be evaluated by the CT technologist&#10;A)quarterly.&#10;B)monthly.&#10;C)weekly.&#10;D)daily.

Accepted Answer

The Water CT Number and Standard Deviation (Noise) evaluation is part of the CT technologist's daily duties for ACR accreditation.

Question 4

A visual inspection of a CT unit should be evaluated at least _____ for ACR accreditation programs.&#10;A)daily.&#10;B)weekly.&#10;C)monthly.&#10;D)semi-annually.

Accepted Answer

The visual inspection is part of the CT technologist's monthly duties for ACR accreditation.

Question 5

The CTDI&#7525;&#8338;&#8343; pass/fail criterion for an adult abdomen is ____ mGy.&#10;A)20&#10;B)40&#10;C)30&#10;D)80

Accepted Answer

The appropriate CTDIᵥₒₗ pass/fail criterion for an adult abdomen is 30 mGy. This ensures that the radiation dose received by the patient is within safe limits while still providing high-quality diagnostic images. Choosing A (20 mGy) or B (40 mGy) would either be too conservative or too liberal, respectively. Choosing D (80 mGy) would result in an unacceptably high radiation dose.

Question 6

The uniformity of the CT number of water should not vary by more than ____ HU from the center of the phantom to the periphery.&#10;A)2&#10;B)3&#10;C)5&#10;D)10

Accepted Answer

Edge-to-center mean CT number difference must be less than 5 HU for all four edge positions.

Question 7

The CT number of water should not deviate by more than ____ CT numbers from 0.&#10;A)2&#10;B)3&#10;C)5&#10;D)10

Accepted Answer

The CT number of water should be 0, but there may be slight variations due to different factors such as the temperature of water and the scanner used. A deviation of 3 CT numbers is considered acceptable and within the range of tolerance. Deviations beyond 3 CT numbers may affect the accuracy of the image and the diagnosis. Therefore, choice B is the best answer.

Question 8

Section thickness should not vary by more than ____ mm for sections greater than 5 mm.&#10;A)&#177;0.5&#10;B)&#177;1.0&#10;C)&#177;2.0&#10;D)&#177;5.0

Accepted Answer

According to ASTM E112-13, section thickness should not vary by more than ±1.0 mm for sections greater than 5 mm. This is to ensure consistent and accurate measurements for metallographic analysis.

Question 9

For a slice thickness of 5 mm or less, the slice thickness should not vary by more than ____ mm.&#10;A)0.5&#10;B)1.0&#10;C)2.0&#10;D)3.0

Accepted Answer

If the slice thickness is 5 mm or more, the slice thickness should not vary more than ±1 mm from the intended slice thickness. If it is 5 mm or less, the slice thickness should not vary more than ±0.5 mm.

Question 10

Patient dose values for CT scans should remain within ____ of the manufacturer's specifications.&#10;A)&#177;2%&#10;B)&#177;5%&#10;C)&#177;10%&#10;D)&#177;20%

Accepted Answer

Patient dose values for CT scans should remain within ±10% of the manufacturer's specifications to ensure safety and accuracy in diagnostic imaging.

Deck 12: Quality Control in Computed Tomography