Computed Tomography Flashcards
7 cards from real Computed Tomography Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Computed Tomography flashcards as text
Which phase of contrast enhancement is optimal for detecting hypervascular liver lesions such as hepatocellular carcinoma?
Answer: Arterial phase (20–35 seconds post-injection)
Hypervascular lesions like HCC receive predominantly arterial blood supply and enhance brightly relative to normal liver parenchyma during the arterial phase.
What is the primary radiation protection principle that requires justifying each CT examination?
Answer: Justification
Justification is the ICRP principle requiring that no examination be performed unless the expected benefit exceeds the radiation detriment to the individual.
In CT, what does 'z-axis resolution' refer to?
Answer: Spatial resolution along the longitudinal (head-to-foot) axis of the patient
Z-axis (longitudinal) resolution determines the ability to distinguish structures stacked along the patient's long axis and improves with thinner collimation.
Which CT scan parameter most directly controls the number of photons reaching the detector?
Answer: mAs
mAs (milliampere-seconds) determines the total quantity of X-ray photons produced; doubling mAs doubles photon flux and roughly halves quantum noise.
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?
Answer: Acute contrast reaction including anaphylaxis
Acute adverse reactions including anaphylaxis can occur within minutes of IV iodinated contrast administration and require immediate recognition and intervention.
What is the name of the CT artifact that appears as concentric rings centered on the isocenter?
Answer: Ring artifact
Ring artifacts are caused by defective or miscalibrated detector elements and manifest as circular bands centered on the gantry rotation axis.
Which modality provides ionizing radiation-free cross-sectional imaging and is preferred for repeated abdominal follow-up in young patients?
Answer: Magnetic resonance imaging (MRI)
MRI uses magnetic fields and radiofrequency pulses with no ionizing radiation, making it safer for serial follow-up imaging in young or pediatric populations.