FRCR FRCR Physics and Radiation Safety 3

Question 1

What is the primary purpose of the 'as low as reasonably achievable' (ALARA) principle?

Accepted Answer

Minimize radiation dose while maintaining diagnostic quality

Answer

ALARA requires that radiation exposure be kept as low as reasonably achievable, balancing radiation risk against the diagnostic or therapeutic benefit.

Question 2

Which radioisotope is used in most nuclear medicine diagnostic studies in the US?

Accepted Answer

Technetium-99m

Answer

Technetium-99m is the most widely used diagnostic radioisotope because of its ideal 6-hour half-life, 140 keV gamma energy, and generator availability.

Question 3

Stochastic effects of radiation are characterized by:

Accepted Answer

Increasing probability with dose, no threshold

Answer

Stochastic effects (cancer, hereditary effects) have a probability that increases with dose but no established threshold; their severity does not depend on dose.

Question 4

What is the typical effective dose from a chest radiograph (PA projection)?

Accepted Answer

0.02 mSv

Answer

A PA chest radiograph delivers approximately 0.02 mSv effective dose, equivalent to about 2–3 days of natural background radiation.

Question 5

Which material is most commonly used for radiation shielding in X-ray rooms?

Accepted Answer

Lead

Answer

Lead is the standard shielding material due to its high atomic number, high density, and ease of incorporation into walls and protective aprons.

FRCR - Fellow of the Royal College of Radiologists Practice Test

FRCR - Fellow of the Royal College of Radiologists Practice Test

FRCR FRCR Physics and Radiation Safety 3