Computed Tomography Test Computed Tomography 4

Question 1

During a CT pulmonary angiography (CTPA), the technologist observes the pulmonary arteries are not well opacified. What is the most likely cause?

Accepted Answer

Scan initiated too early before contrast reaches the pulmonary arteries

Answer

CTPA timing is critical; scanning before contrast bolus reaches the pulmonary circulation results in non-diagnostic images — bolus tracking or test bolus timing is used to prevent this.

Question 2

What is the CTDI (Computed Tomography Dose Index) primarily used to measure?

Accepted Answer

Scanner radiation output for a single axial scan

Answer

CTDI measures the average absorbed dose within the scan volume from a single rotation and is used as a standardized descriptor of scanner output, not true patient effective dose.

Question 3

Which type of iodinated contrast agent has the lowest risk of adverse reactions?

Accepted Answer

Low-osmolality nonionic monomers

Answer

Low-osmolality nonionic monomers (e.g., iohexol, iopamidol) have the lowest rates of adverse reactions due to reduced chemotoxicity and near-physiologic osmolality.

Question 4

A patient's CT of the chest shows a focal area of ground-glass opacity (GGO). What does GGO characteristically represent?

Accepted Answer

Partial filling of alveoli or interstitial thickening with preserved underlying architecture

Answer

GGO appears as a hazy increased attenuation that does not obscure underlying vessels or bronchi, reflecting partial alveolar filling or thickened interstitium.

Question 5

Which of the following best describes 'iterative reconstruction' in modern CT?

Accepted Answer

A computational algorithm that repeatedly refines the image to reduce noise while preserving spatial resolution

Answer

Iterative reconstruction algorithms model the CT acquisition process and iteratively update the image estimate to reduce noise, allowing diagnostic quality at lower radiation doses.

Computed Tomography Test Practice Test

Computed Tomography Test Practice Test

Computed Tomography Test Computed Tomography 4