ARRT Radiation Safety 5

Question 1

Which phantom is used to measure CTDI100 according to the standard FDA/IEC protocol?

Accepted Answer

A 16 cm diameter PMMA phantom for head and a 32 cm phantom for body

Answer

The FDA/IEC protocol uses a 16 cm PMMA phantom for head measurements and a 32 cm phantom for body measurements to derive CTDI100.

Question 2

A CT technologist notices the dose reference level (DRL) for a routine chest CT is being routinely exceeded. The BEST first step is to:

Accepted Answer

Review and optimize the scan protocol to determine if dose can be reduced without compromising diagnostic quality

Answer

DRLs serve as benchmarks; exceeding them triggers a protocol review to identify optimization opportunities while preserving diagnostic image quality.

Question 3

What is the primary radiation hazard associated with CT compared to conventional radiography?

Accepted Answer

Significantly greater patient dose due to multiple rotational acquisitions and extended scan volumes

Answer

CT delivers substantially higher patient doses than conventional radiography because it involves multiple rotational X-ray acquisitions covering large anatomical volumes.

Question 4

Which factor does NOT directly influence the CTDI_vol value displayed on the CT console?

Accepted Answer

Reconstruction kernel (filter)

Answer

Reconstruction kernel is a post-processing parameter applied after data acquisition and does not change the radiation output; CTDI_vol reflects acquisition parameters only.

Question 5

A technologist is scanning a patient with metal hip implants. To reduce dose while managing metal artifact, which approach is MOST appropriate?

Accepted Answer

Use metal artifact reduction (MAR) software at standard dose rather than routinely increasing mAs

Answer

Metal artifact reduction software effectively manages implant artifacts at standard dose; routinely increasing mAs adds unnecessary patient dose without eliminating artifacts.

(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 5