Computed Tomography Test Cheat Sheet 2026

The 30 highest-yield Computed Tomography Test facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is the purpose of 'prospective triggering' in cardiac CT? → To acquire data only during a specific, predetermined phase of the cardiac cycle
2. What is the primary shielding material used in CT scanning room walls? → Lead or lead-equivalent concrete
3. The term 'Z-axis dose profile' in CT refers to dose distribution along which direction? → Patient cranio-caudal (head-to-foot) axis
4. Which detector material is most commonly used in modern solid-state CT detectors? → Gadolinium oxysulfide (GOS)
5. What is the function of the analog-to-digital converter (ADC) in a CT system? → To convert the electrical detector signal into digital data for processing
6. What is the most appropriate CT protocol to evaluate a patient presenting with acute stroke within the therapeutic window? → Non-contrast CT brain followed by CT perfusion and CT angiography
7. Which reconstruction algorithm provides the sharpest images but also the most noise in CT? → High-frequency (bone/edge) kernel
8. A patient with a creatinine level of 2.8 mg/dL is scheduled for contrast-enhanced CT. What is the most appropriate next step? → Consult with the ordering physician regarding contrast risk and alternatives
9. What procedure results in a more monochromatic beam and lowers patient radiation exposure by reducing the longest wavelength photons? → Filtration
10. On a CT brain, the pineal gland is noted to be shifted 5 mm to the left of midline. This finding most directly suggests: → A right-sided mass or edema causing midline shift
11. Which reconstruction filter (kernel) would be most appropriate for evaluating fine bony detail in CT? → Sharp/bone kernel
12. Which parameter directly determines the thickness of a CT slice in single-detector row scanners? → Detector aperture width
13. On CT of the spine, which finding is most indicative of an acute compression fracture? → Loss of vertebral body height with band-like edema pattern on CT (marrow hyperdensity)
14. The 'effective dose' in CT differs from absorbed dose (Gy) in that it accounts for: → Tissue weighting factors and radiation type
15. Which window setting is most appropriate for evaluating brain parenchyma on CT? → Window width 80 HU, level 40 HU
16. On a CT abdomen, a lesion measures -120 HU. What does this attenuation value suggest? → Fat-containing lesion (lipoma or angiomyolipoma)
17. What is the function of the CT gantry? → Contains the rotating X-ray tube and detector array that surrounds the patient
18. Which type of CT scan is specifically designed for imaging the coronary arteries and assessing heart health? → Cardiac CT
19. What is the primary purpose of a bow-tie filter in a CT scanner? → To shape the X-ray beam and reduce dose to peripheral tissues
20. Which oral contrast agent is preferred in CT when bowel perforation is suspected? → Water-soluble iodinated contrast (e.g., Gastrografin)
21. In CT imaging, what does the term "slice thickness" refer to? → The distance between adjacent slices
22. What is the primary advantage of dual-energy CT (DECT) over single-energy CT? → Ability to characterize tissue composition based on material decomposition
23. What does the term 'pitch' refer to in helical CT? → Table movement per rotation divided by total beam collimation
24. In CT, what does 'z-axis resolution' refer to? → Spatial resolution along the longitudinal (head-to-foot) axis of the patient
25. Which term describes the ability of a CT scanner to accurately represent small objects or structures in the images? → Spatial resolution
26. What is the term for the minimum detectable difference in attenuation between two adjacent structures in CT? → Contrast resolution
27. What effect does increasing CT tube voltage (kVp) have on patient dose? → Increases dose due to higher photon energy and greater beam penetration
28. Which component of a CT scanner is responsible for rotating the X-ray tube and detector around the patient? → Gantry
29. A ring artifact on a CT image is most likely caused by: → A faulty detector element
30. In iterative reconstruction (IR), image quality is improved compared to FBP primarily by: → Modeling noise and system physics to suppress artifacts