ARRT Radiation Safety 4

Question 1

Which of the following correctly defines 'effective dose' (E) in radiation protection?

Accepted Answer

The weighted sum of equivalent doses to all irradiated tissues, reflecting overall stochastic risk

Answer

Effective dose uses tissue weighting factors to sum equivalent doses across organs, yielding a single value (in mSv) that represents whole-body stochastic risk.

Question 2

For a pediatric CT head scan, compared to an adult protocol, the technologist should generally:

Accepted Answer

Reduce mAs significantly because children are more radiosensitive and smaller

Answer

Children have greater radiosensitivity and smaller body dimensions, so pediatric CT protocols use substantially lower mAs than adult protocols.

Question 3

The annual occupational dose limit for the lens of the eye, as updated by NCRP Report No. 172, is:

Accepted Answer

20 mSv

Answer

NCRP Report No. 172 (2016) lowered the recommended annual occupational lens dose limit to 20 mSv/year averaged over 5 years, consistent with ICRP 103.

Question 4

Which of the following patient populations has the HIGHEST radiosensitivity?

Accepted Answer

Fetuses and children under 5 years of age

Answer

Fetuses and young children are most radiosensitive due to rapidly dividing cells and longer life expectancy over which stochastic effects can manifest.

Question 5

During a multi-phase CT liver protocol (non-contrast, arterial, portal venous, delayed), which action BEST reduces cumulative patient dose?

Accepted Answer

Eliminate phases not essential for the clinical indication and use dose modulation for each phase

Answer

Eliminating unnecessary scan phases and applying tube current modulation to each remaining phase are the most effective strategies to reduce cumulative multi-phase CT dose.

(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 4