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Question 1. Which of the following is the most appropriate initial step when preparing a patient for a contrast‑enhanced CT scan? A) Start the power injector immediately B) Verify the patient’s pregnancy status C) Administer a pre‑medication antihistamine without checking allergies D) Perform a full cardiac work‑up Answer: B Explanation: Screening for pregnancy is essential before administering iodinated contrast to prevent fetal exposure. Question 2. A patient’s most recent serum creatinine is 2.1 mg/dL and their estimated GFR is 35 mL/min/1.73 m². Which statement is correct regarding IV contrast use? A) Contrast is contraindicated in all cases B) Low‑osmolar non‑ionic contrast may be used with pre‑hydration C) Only oral contrast should be used D) No contrast is needed for abdominal imaging Answer: B Explanation: In patients with reduced GFR, low‑osmolar non‑ionic contrast can be administered safely if adequate IV hydration is provided. Question 3. Which laboratory value best predicts a patient’s risk for bleeding when receiving contrast? A) Serum calcium
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B) PT/INR
C) Serum sodium D) Hemoglobin Answer: B Explanation: PT/INR reflects coagulation status and helps assess bleeding risk, especially when contrast may be combined with anticoagulants. Question 4. During a CT scan, the technologist notices the patient’s oxygen saturation has dropped to 88 %. The most appropriate immediate action is to: A) Increase the scan speed B) Pause the scan and administer supplemental oxygen C) Continue scanning and note the value D) Lower the tube voltage Answer: B Explanation: Patient safety takes priority; supplemental oxygen should be provided before proceeding. Question 5. Which of the following contrast agents has the highest osmolarity? A) Iohexol (non‑ionic, low‑osmolar) B) Iodixanol (non‑ionic, iso‑osmolar) C) Iopamidol (non‑ionic, low‑osmolar) D) Diatrizoate (ionic, high‑osmolar)
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Question 8. The drug of choice for treating an anaphylactic reaction to contrast media is: A) Atropine B) Epinephrine C) Diphenhydramine D) Diazepam Answer: B Explanation: Epinephrine rapidly reverses airway obstruction, hypotension, and bronchospasm in anaphylaxis. Question 9. In the ALARA principle, “as low as reasonably achievable” primarily refers to: A) Image noise B) Radiation dose to the patient C) Scan time D) Contrast volume Answer: B Explanation: ALARA emphasizes minimizing radiation exposure while maintaining diagnostic image quality. Question 10. Which physical interaction is responsible for the majority of X‑ray production in a CT tube? A) Photoelectric effect B) Compton scattering
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C) Bremsstrahlung radiation D) Pair production Answer: C Explanation: High‑energy electrons decelerating in the anode produce Bremsstrahlung X‑rays, the main component of CT beams. Question 11. In CT imaging, bone appears bright because: A) It has low attenuation B) It has high attenuation of X‑rays C) It emits radiation D) It is highly vascular Answer: B Explanation: Bone’s high atomic number causes strong X‑ray attenuation, resulting in high Hounsfield units (bright). Question 12. Which tissue type is most susceptible to deterministic radiation effects? A) Lung B) Bone marrow C) Skin D) Brain
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Question 15. Which reconstruction technique is most effective at reducing image noise in low‑dose CT scans? A) Filtered back‑projection (FBP) B) Standard convolution kernel C) Iterative reconstruction (IR) D) Linear interpolation Answer: C Explanation: Iterative reconstruction algorithms model noise and can produce clearer images at reduced dose. Question 16. The term “pitch” in helical CT refers to: A) The ratio of table movement per rotation to the beam collimation width B) The angle of the X‑ray beam C) The detector element size D) The kilovoltage setting Answer: A Explanation: Pitch = table travel per rotation ÷ total collimated slice width; it influences scan speed and dose. Question 17. When performing a CT of the abdomen with a 0.5 mm slice thickness, the appropriate display field of view (DFOV) to visualize the liver should be: A) 5 cm
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B) 20 cm C) 50 cm D) 100 cm Answer: B Explanation: A DFOV of about 20 cm adequately displays the liver while preserving spatial resolution. Question 18. Which post‑processing technique best displays vascular structures in a CT angiogram? A) Maximum intensity projection (MIP) B) Minimum intensity projection (MinIP) C) Volume rendering with bone algorithm D) Edge enhancement filter Answer: A Explanation: MIP projects the highest attenuation voxels, emphasizing contrast‑filled vessels. Question 19. Beam hardening artifacts most commonly appear as: A) Streaks radiating from metallic implants B) Dark bands (cupping) near dense bone C) Uniformly increased noise D) Motion blur Answer: B
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A) Current smoker aged 45‑55 with 10 pack‑years B) Former smoker aged 55‑80 with ≥30 pack‑years, quit ≤ 15 years ago C) Non‑smoker with chronic cough D) Any patient with a family history of lung cancer Answer: B Explanation: USPSTF recommends LDCT for adults 55‑80 who have a ≥30 pack‑year smoking history and have quit within the past 15 years. Question 23. In dual‑energy CT, the two different kVp settings are primarily used to: A) Increase scan speed B) Differentiate materials based on their attenuation characteristics C) Reduce patient dose D) Eliminate the need for contrast Answer: B Explanation: Dual‑energy acquisition exploits the energy‑dependent attenuation of different substances, allowing material decomposition. Question 24. Which component of the CT gantry rotates around the patient? A) Slip ring B) Detector array C) X‑ray tube housing only
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D) Both the X‑ray tube and detector array Answer: D Explanation: The X‑ray tube and detector assembly rotate together around the patient, while the slip ring provides continuous electrical contact. Question 25. The primary advantage of axial (step‑and‑shoot) scanning over helical scanning is: A) Faster acquisition time B) Higher spatial resolution with less motion artifact C) Lower radiation dose D) Ability to perform dual‑energy scans Answer: B Explanation: Axial scanning acquires each slice individually, reducing motion artifacts and often yielding higher spatial resolution. Question 26. Which of the following CT protocols is most appropriate for evaluating acute ischemic stroke within the first 6 hours? A) Non‑contrast head CT only B) CT perfusion with contrast C) CT angiography of the neck and head D) All of the above Answer: D
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Question 29. When performing a CT‑guided lung biopsy, the most important factor to minimize pneumothorax risk is: A) Using a larger gauge needle B) Selecting a peripheral approach through aerated lung C) Performing the procedure in deep inspiration D) Avoiding any sedation Answer: B Explanation: A peripheral approach reduces the length of aerated lung traversed, decreasing pneumothorax incidence. Question 30. In a CT of the spine, the “halo sign” around a vertebral body most likely represents: A) Osteoporotic fracture B) Metastatic lesion with peripheral edema C) Hemangioma D) Infection Answer: B Explanation: The halo sign (low‑attenuation rim) often indicates a metastatic lesion with surrounding reactive edema. Question 31. Which of the following best describes the effect of increasing kVp on patient dose and image contrast? A) Dose increases, contrast decreases
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B) Dose decreases, contrast increases C) Both dose and contrast increase D) Dose decreases, contrast decreases Answer: A Explanation: Higher kVp raises photon energy, increasing dose but reducing tissue contrast because attenuation differences become less pronounced. Question 32. The most appropriate shielding for a pregnant patient undergoing a CT scan of the abdomen is: A) Full lead apron covering the entire body B) Bismuth breast shield only C) No shielding, but use dose‑reduction techniques D) Lead shield over the fetus Answer: C Explanation: Lead shielding over the abdomen is ineffective for CT; instead, dose‑reduction strategies (e.g., low‑dose protocol, ATCM) are preferred. Question 33. Which term describes the amount of radiation absorbed per unit mass of tissue? A) Effective dose B) Absorbed dose (Gy) C) Dose‑length product D) CTDIvol
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Question 36. Which of the following is an example of a stochastic radiation effect? A) Skin erythema B) Cataract formation C) Radiation‑induced cancer D) Hair loss Answer: C Explanation: Stochastic effects have no dose threshold and probability increases with dose; cancer is a classic example. Question 37. The purpose of a “pitch factor” greater than 1 in helical scanning is to: A) Decrease scan time and patient dose B) Increase spatial resolution C) Reduce image noise D) Improve contrast resolution Answer: A Explanation: A pitch >1 means the table moves faster than the beam width per rotation, shortening scan time and lowering dose. Question 38. In a CT brain perfusion study, which parameter reflects cerebral blood flow (CBF)? A) Time‑to‑peak (TTP)
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B) Mean transit time (MTT) C) Cerebral blood volume (CBV) D) CBF (directly measured) Answer: D Explanation: Perfusion software calculates CBF directly from contrast passage curves; the other parameters are related but not CBF. Question 39. When using a power injector for IV contrast, the recommended maximum injection rate for a 70 kg adult with a 20‑gauge IV catheter is: A) 1 mL/s B) 2 mL/s C) 3 mL/s D) 5 mL/s Answer: C Explanation: A 20‑gauge catheter can safely accommodate up to 3 mL/s for most adult contrast injections. Question 40. Which artifact is most likely to appear when scanning a patient with a pacemaker? A) Beam hardening streaks B) Metal‑induced photon starvation artifacts C) Motion blur D) Partial volume averaging
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Question 43. In a CT abdomen with a pancreatic protocol, the “arterial phase” is typically obtained at what time after contrast injection? A) 10‑ 15 seconds B) 30‑ 40 seconds C) 60‑ 70 seconds D) 90‑ 120 seconds Answer: B Explanation: The arterial phase peaks around 30‑ 40 seconds post‑injection, optimizing arterial enhancement of the pancreas. Question 44. Which imaging modality is most appropriate for confirming a suspected aortic dissection identified on CT? A) MRI with gadolinium B) Ultrasound with Doppler C) Conventional angiography D) Repeat CT with higher resolution Answer: C Explanation: Conventional angiography remains the gold standard for definitive diagnosis of aortic dissection. Question 45. When performing a CT of the temporal bone, the technologist should use a slice thickness of:
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A) 5 mm B) 3 mm C) 1 mm or less D) 10 mm Answer: C Explanation: High‑resolution temporal bone imaging requires sub‑millimeter slices to visualize tiny bony structures. Question 46. Which of the following statements about CT dose‑length product (DLP) is correct? A) DLP is independent of scan length B) DLP is directly proportional to CTDIvol and scan length C) DLP measures the effective dose in millisieverts D) DLP is only used for pediatric protocols Answer: B Explanation: DLP = CTDIvol × scan length; it reflects the total radiation output for a given examination. Question 47. During a CT scan, the technologist observes “ring artifacts” on the reconstructed images. The most likely cause is: A) Detector element failure B) Patient motion C) Beam hardening
