DHA Diagnostic Imaging & Radiology 5

Question 1

Which nuclear medicine scan is most appropriate for detecting occult bony metastases in a cancer patient?

Accepted Answer

Tc-99m bone scan

Answer

Tc-99m methylene diphosphonate bone scintigraphy is sensitive for osteoblastic metastatic lesions and is widely used for whole-body skeletal survey.

Question 2

In computed tomography, the Hounsfield Unit (HU) value for simple water is:

Accepted Answer

0 HU

Answer

The Hounsfield scale sets water at 0 HU as the reference point, with air at -1000 HU and cortical bone at approximately +1000 HU.

Question 3

Which ultrasound artifact is caused by a highly reflective structure that prevents sound from passing through, creating a dark region behind it?

Accepted Answer

Acoustic shadowing

Answer

Acoustic shadowing occurs when structures like gallstones or bones reflect nearly all the ultrasound beam, creating a shadow of no signal distal to them.

Question 4

A 'Hampton's hump' on chest radiograph is associated with:

Accepted Answer

Pulmonary embolism with infarction

Answer

Hampton's hump is a pleural-based, wedge-shaped opacity caused by pulmonary infarction secondary to embolic occlusion of a pulmonary artery.

Question 5

What is the recommended maximum cumulative dose of ionizing radiation considered acceptable for occupational workers per year according to international radiation protection standards?

Accepted Answer

20 mSv/year

Answer

The ICRP recommends an effective dose limit of 20 mSv per year averaged over 5 years for occupational radiation workers.

DHA - Dubai Health Authority Practice Test

DHA - Dubai Health Authority Practice Test

DHA Diagnostic Imaging & Radiology 5