ARRT Radiation Protection Principles 4

Question 1

Which cell type is considered the most radiosensitive in the human body?

Accepted Answer

Lymphocytes

Answer

Lymphocytes are highly radiosensitive and show decreases in count at relatively low doses, making them a useful biological indicator of exposure.

Question 2

The occupational lens of eye dose limit per year is set at what value by NCRP?

Accepted Answer

150 mSv

Answer

NCRP sets the annual occupational equivalent dose limit for the lens of the eye at 150 mSv (15 rem).

Question 3

Which factor describes the relative biological effectiveness of different radiation types and is used to calculate equivalent dose?

Accepted Answer

Quality factor (Q) or radiation weighting factor (wR)

Answer

The radiation weighting factor (wR), formerly called quality factor, converts absorbed dose to equivalent dose by accounting for radiation type's biological effectiveness.

Question 4

Adding filtration to an X-ray beam primarily reduces patient dose by:

Accepted Answer

Removing low-energy photons that would be absorbed in superficial tissues

Answer

Added filtration (typically aluminum) absorbs low-energy photons that would deposit dose in superficial tissue without contributing to the image.

Question 5

What is the minimum total filtration required for X-ray tubes operating above 70 kVp, per federal regulation?

Accepted Answer

2.5 mm Al equivalent

Answer

Federal regulations (21 CFR 1020.30) require a minimum total filtration of 2.5 mm aluminum equivalent for tubes operating above 70 kVp.

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT Radiation Protection Principles 4