FRCR MCQ 3

Question 1

Which statement best describes the radiation weighting factor (wR) for neutrons of 1 MeV energy?

Accepted Answer

wR = 20, reflecting high relative biological effectiveness

Answer

Fast neutrons (around 1 MeV) have a radiation weighting factor of 20, reflecting their high linear energy transfer and relative biological effectiveness compared to X-rays.

Question 2

On gadolinium-enhanced MRI of the liver, which feature best distinguishes a haemangioma from a metastasis?

Accepted Answer

Peripheral nodular enhancement with progressive centripetal fill-in

Answer

Haemangiomas show characteristic peripheral nodular enhancement on early post-contrast phases with progressive centripetal fill-in on delayed images, following blood pool kinetics.

Question 3

In nuclear medicine, which radionuclide is used for myocardial perfusion imaging with the longest physical half-life among common agents?

Accepted Answer

Thallium-201 (T½ = 73 hours)

Answer

Thallium-201 has a physical half-life of approximately 73 hours, which is the longest among commonly used myocardial perfusion imaging agents.

Question 4

A CT of the neck shows a cystic mass at the angle of the mandible that displaces the carotid vessels posteriorly. What is the most likely diagnosis?

Accepted Answer

Second branchial cleft cyst

Answer

Second branchial cleft cysts are the most common branchial anomalies, typically appearing as cystic masses at the anteromedial border of the sternocleidomastoid, displacing the carotid vessels.

Question 5

Which feature on mammography is most suspicious for malignancy?

Accepted Answer

Spiculated mass with architectural distortion

Answer

A spiculated mass with architectural distortion has a very high positive predictive value for malignancy and warrants tissue sampling (BI-RADS 5).

FRCR - Fellow of the Royal College of Radiologists Practice Test

FRCR - Fellow of the Royal College of Radiologists Practice Test

FRCR MCQ 3