ARRT Equipment Operation and Quality Control

Question 1

Which daily CT quality control test verifies that CT numbers (Hounsfield Units) remain accurate and consistent?

Accepted Answer

CT number accuracy/linearity test

Answer

Noise index measurement

Answer

Slice thickness verification

Answer

High-contrast spatial resolution test

Question 2

What is the primary purpose of performing a daily air calibration (warm-up scan) on a CT scanner?

Accepted Answer

To calibrate detector channels and normalize dark current

Answer

To test the table weight limit

Answer

To verify gantry tilt accuracy

Answer

To measure patient dose output

Question 3

Which CT quality control phantom is most commonly used to evaluate CT number accuracy, noise, uniformity, and spatial resolution?

Accepted Answer

AAPM CT performance phantom

Answer

Alderson Rando phantom

Answer

Leeds TOR phantom

Answer

MOSFET dosimetry phantom

Question 4

On a CT scanner, what does image uniformity testing evaluate?

Accepted Answer

The consistency of CT numbers across the field of view in a homogeneous phantom

Answer

The ability to visualize small high-contrast structures

Answer

The accuracy of the patient table indexing

Answer

The linearity of dose output versus mAs

Question 5

Which factor is evaluated by the modulation transfer function (MTF) in CT quality control?

Accepted Answer

High-contrast spatial resolution

Answer

Low-contrast detectability

Answer

Image noise levels

Answer

CT number linearity

Question 6

What is the recommended frequency for performing a full CT equipment performance evaluation by a qualified medical physicist?

Accepted Answer

Annually

Answer

Daily

Answer

Weekly

Answer

Every five years

Question 7

When a CT scanner undergoes a tube replacement, which quality control step is mandatory before returning the unit to clinical service?

Accepted Answer

Full calibration and acceptance testing

Answer

Slice sensitivity profile measurement only

Answer

Low-contrast detectability test only

Answer

Gantry tilt angle verification only