ARRT Equipment Operation and Quality Control 2

Question 1

What does the term 'detector efficiency' refer to in CT scanner performance?

Accepted Answer

The ability of detectors to capture and convert X-ray photons into usable signal

Answer

Detector efficiency describes how effectively CT detectors absorb incident X-ray photons and convert them into electrical signal, directly affecting image quality and dose.

Question 2

In CT quality control, 'low-contrast detectability' refers to the system's ability to:

Accepted Answer

Distinguish objects with small differences in attenuation from background

Answer

Low-contrast detectability measures the scanner's ability to visualize objects with subtle attenuation differences, which is critical for soft-tissue diagnosis.

Question 3

Which of the following best describes the purpose of the CT table indexing accuracy test?

Accepted Answer

To confirm the table moves the correct prescribed distance between scan acquisitions

Answer

Table indexing accuracy testing ensures the patient couch advances exactly the specified distance, which is critical for accurate slice positioning and volume coverage.

Question 4

The 'noise' measured in a CT image is quantified as:

Accepted Answer

The standard deviation of CT numbers in a uniform region of interest

Answer

Image noise in CT is quantified as the standard deviation of HU values within a uniform phantom region; higher standard deviation indicates greater noise.

Question 5

Which generator component is responsible for converting AC power to the high-voltage DC supply required by the X-ray tube in modern CT systems?

Accepted Answer

High-frequency inverter generator

Answer

Modern CT systems use high-frequency inverter generators that convert line AC to high-frequency AC, then rectify it to produce a near-constant high-voltage DC supply for the tube.

(ARRT) American Registry of Radiologic Technologists Computed Tomography Certification Practice Test

(ARRT) American Registry of Radiologic Technologists Computed Tomography Certification Practice Test

ARRT Equipment Operation and Quality Control 2