ARRT Radiation Safety 2

Question 1

Which radiation weighting factor (wR) applies to X-rays used in CT imaging?

Accepted Answer

1

Answer

X-rays and gamma rays have a radiation weighting factor of 1, meaning 1 Gy equals 1 Sv.

Question 2

What is the primary purpose of the CT dose index (CTDI)?

Accepted Answer

To characterize radiation output of a CT scanner independent of patient size

Answer

CTDI characterizes the radiation output of a CT scanner and allows standardized comparison between scanners and protocols.

Question 3

A patient weighing 300 lbs is scanned using a standard adult protocol. How should the technologist respond?

Accepted Answer

Apply size-specific dose estimates (SSDE) and adjust technique for body habitus

Answer

SSDE accounts for patient size and provides a more accurate dose estimate; technique should be adjusted to match body habitus while maintaining diagnostic quality.

Question 4

Which of the following best describes the ALARA principle in CT imaging?

Accepted Answer

Keep radiation exposure as low as reasonably achievable while maintaining diagnostic image quality

Answer

ALARA means optimizing dose to the lowest level that still yields diagnostically acceptable images for the clinical indication.

Question 5

The dose length product (DLP) is calculated by multiplying CTDI_vol by which parameter?

Accepted Answer

Scan length (cm)

Answer

DLP = CTDI_vol × scan length (cm), providing a single value that reflects the total radiation energy deposited during the scan.

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

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

ARRT Radiation Safety 2