FRCR FRCR Radiation Physics and Dosimetry 1

Question 1

Which unit is used to express absorbed radiation dose in the SI system?

Accepted Answer

Gray (Gy)

Answer

The Gray (Gy) is the SI unit of absorbed dose, defined as 1 joule of energy deposited per kilogram of tissue.

Question 2

What does the radiation weighting factor (wR) account for when calculating equivalent dose?

Accepted Answer

Biological effectiveness of different radiation types

Answer

The radiation weighting factor adjusts for the relative biological effectiveness of different types of ionizing radiation when calculating equivalent dose in Sieverts.

Question 3

Which of the following best describes the half-value layer (HVL) of an X-ray beam?

Accepted Answer

Thickness of material that reduces beam intensity by 50%

Answer

The HVL is the thickness of a specified material required to reduce the X-ray beam intensity (or air kerma rate) to exactly half its original value.

Question 4

In X-ray production, which interaction is primarily responsible for the continuous bremsstrahlung spectrum?

Accepted Answer

Deceleration of electrons in the Coulomb field of nuclei

Answer

Bremsstrahlung ('braking radiation') is produced when high-speed electrons are decelerated by the strong electric field of target nuclei, emitting X-ray photons with a continuous energy spectrum.

Question 5

What is the primary purpose of added filtration in a diagnostic X-ray tube?

Accepted Answer

Remove low-energy photons to reduce patient skin dose

Answer

Added filtration (typically aluminum) preferentially attenuates low-energy photons that would be absorbed by the patient's skin without contributing to image formation.

FRCR - Fellowship of the Royal College of Radiologists Practice Test

FRCR - Fellowship of the Royal College of Radiologists Practice Test

FRCR FRCR Radiation Physics and Dosimetry 1