Computed Tomography Test Computed Tomography (CT) 3

Question 1

Which type of CT artifact appears as alternating dark and bright bands radiating from high-density objects like metal implants?

Accepted Answer

Beam hardening artifact

Answer

Beam hardening occurs when lower-energy photons are preferentially absorbed by dense materials, causing streaks or dark bands near metal or bone.

Question 2

In CT, what does the Hounsfield unit (HU) value of approximately -100 indicate?

Accepted Answer

Fat

Answer

Fat typically measures between -50 and -150 HU, with approximately -100 HU being a classic fat attenuation value, while air is near -1000 HU.

Question 3

What is the primary indication for CT perfusion imaging of the brain?

Accepted Answer

Assessment of cerebrovascular ischemia and infarct core vs. penumbra

Answer

CT perfusion maps cerebral blood flow, blood volume, and mean transit time to differentiate irreversibly infarcted tissue from salvageable ischemic penumbra in acute stroke.

Question 4

Which oral contrast agent is preferred in CT when bowel perforation is suspected?

Accepted Answer

Water-soluble iodinated contrast (e.g., Gastrografin)

Answer

Water-soluble iodinated agents are used when perforation is suspected because barium leaking into the peritoneum causes severe peritonitis.

Question 5

What is the normal attenuation range (HU) for the liver parenchyma on a non-contrast CT?

Accepted Answer

50 to 70 HU

Answer

Normal liver parenchyma measures approximately 50–70 HU on non-contrast CT, slightly higher than the spleen under normal conditions.

Computed Tomography Test Practice Test

Computed Tomography Test Practice Test

Computed Tomography Test Computed Tomography (CT) 3