Computed Tomography Test Computed Tomography 3

Question 1

Which phase of contrast enhancement is optimal for detecting hypervascular liver lesions such as hepatocellular carcinoma?

Accepted Answer

Arterial phase (20–35 seconds post-injection)

Answer

Hypervascular lesions like HCC receive predominantly arterial blood supply and enhance brightly relative to normal liver parenchyma during the arterial phase.

Question 2

What is the primary radiation protection principle that requires justifying each CT examination?

Accepted Answer

Justification

Answer

Justification is the ICRP principle requiring that no examination be performed unless the expected benefit exceeds the radiation detriment to the individual.

Question 3

In CT, what does 'z-axis resolution' refer to?

Accepted Answer

Spatial resolution along the longitudinal (head-to-foot) axis of the patient

Answer

Z-axis (longitudinal) resolution determines the ability to distinguish structures stacked along the patient's long axis and improves with thinner collimation.

Question 4

Which CT scan parameter most directly controls the number of photons reaching the detector?

Accepted Answer

mAs

Answer

mAs (milliampere-seconds) determines the total quantity of X-ray photons produced; doubling mAs doubles photon flux and roughly halves quantum noise.

Question 5

A patient receives 120 mL of iodinated contrast at 4 mL/s via antecubital IV. Which complication should the technologist monitor for immediately after injection?

Accepted Answer

Acute contrast reaction including anaphylaxis

Answer

Acute adverse reactions including anaphylaxis can occur within minutes of IV iodinated contrast administration and require immediate recognition and intervention.

Computed Tomography Test Practice Test

Computed Tomography Test Practice Test

Computed Tomography Test Computed Tomography 3