DHA Diagnostic Imaging & Radiology 2

Question 1

MRI is absolutely contraindicated in patients with which of the following?

Accepted Answer

Older pacemakers without MR-conditional labeling

Answer

Conventional (non-MR-conditional) pacemakers are an absolute contraindication to MRI due to risk of device malfunction, inappropriate pacing, or heat generation from radiofrequency energy.

Question 2

What does a Hounsfield Unit (HU) value of +1000 typically represent in CT imaging?

Accepted Answer

Cortical bone

Answer

Cortical bone has a Hounsfield Unit value of approximately +1000 HU, reflecting its high attenuation of X-rays due to calcium content.

Question 3

Ultrasound imaging is based on which physical principle?

Accepted Answer

Reflection of high-frequency sound waves

Answer

Ultrasound uses high-frequency sound waves (2–15 MHz) that are emitted and received by a transducer; echoes reflected at tissue interfaces are converted into images.

Question 4

Which chest radiograph positioning is most sensitive for detecting a small pneumothorax?

Accepted Answer

Erect PA

Answer

An erect PA chest radiograph is most sensitive for pneumothorax because free pleural air rises to the apex when the patient is upright, creating a visible pleural line.

Question 5

Fluoroscopy is most appropriately used for which clinical application?

Accepted Answer

Real-time dynamic imaging of swallowing or joint motion

Answer

Fluoroscopy provides continuous real-time X-ray imaging, making it ideal for dynamic studies such as barium swallow, arthrography, and interventional guidance.

DHA - Dubai Health Authority Practice Test

DHA - Dubai Health Authority Practice Test

DHA Diagnostic Imaging & Radiology 2