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Ultimate Exam
Question 1. Which of the following is the most important reason to obtain a detailed medication history before administering iodinated contrast? A) To calculate the correct contrast volume B) To assess for potential contrast-induced nephropathy risk C) To determine the patient’s blood type D) To schedule the scan at the optimal time of day Answer: B Explanation: Certain medications (e.g., NSAIDs, metformin) can increase the risk of contrast-induced nephropathy; knowing them allows the technologist to take preventive measures. Question 2. Informed consent for a CT angiography of the chest must include which of the following elements? A) Detailed description of the scanner’s mechanical components B) Explanation of radiation risks, contrast risks, and alternatives C) A list of all possible incidental findings D) The exact cost of the procedure Answer: B Explanation: Informed consent requires disclosure of risks (radiation, contrast reactions), benefits, and alternatives so the patient can make an educated decision. Question 3. Which vital sign is most critical to assess before performing a contrast-enhanced CT in a patient with known cardiac arrhythmia? A) Respiratory rate B) Blood pressure C) Heart rate and rhythm (ECG) D) Temperature
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Answer: C Explanation: Arrhythmias can affect timing of contrast bolus and may predispose to adverse reactions; confirming heart rhythm ensures safe contrast administration. Question 4. A patient’s eGFR is reported as 45 mL/min/1.73 m². Which action is most appropriate regarding iodinated contrast administration? A) Proceed with standard contrast dose B) Use a reduced contrast volume and low-osmolar non-ionic agent C) Cancel the exam and schedule a MRI instead D) Administer the contrast without any modification Answer: B Explanation: An eGFR <60 mL/min/1.73 m² indicates reduced renal function; using a low-osmolar, non-ionic contrast at a reduced volume lowers nephrotoxicity risk. Question 5. Which of the following best describes the “Time-out” procedure in CT imaging? A) A pause to allow the patient to relax before scanning B) A verification step to confirm patient identity, procedure, and site before exposure C) The interval between contrast injection and image acquisition D) The time taken to calibrate the scanner each day Answer: B Explanation: “Time-out” is a safety protocol to prevent wrong-patient or wrong-procedure errors by confirming key information before radiation exposure. Question 6. Which contrast media type has the highest osmolarity?
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Explanation: Elevation and cold compress help reduce swelling and pain; high-pressure compression could worsen tissue injury. Question 9. Which of the following is a mild contrast reaction? A) Laryngeal edema requiring epinephrine B) Urticaria (hives) without respiratory compromise C) Severe bronchospasm D) Anaphylactic shock Answer: B Explanation: Hives without systemic involvement are classified as a mild reaction; moderate and severe reactions involve respiratory or cardiovascular compromise. Question 10. In the event of a severe anaphylactic reaction to contrast, which medication is the first-line treatment? A) Diphenhydramine B) Epinephrine intramuscular injection C) Prednisone oral dose D) Albuterol inhalation only Answer: B Explanation: Epinephrine is the life-saving drug for anaphylaxis; antihistamines and steroids are adjuncts. Question 11. Bremsstrahlung radiation is produced when: A) An inner-shell electron is ejected from the target atom B) A high-energy electron is decelerated in the target material C) An electron transitions between atomic shells
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D) Photons are absorbed by the patient’s tissues Answer: B Explanation: Bremsstrahlung (braking radiation) results from the deceleration of high-energy electrons as they interact with the target nucleus. Question 12. The characteristic X-ray peaks observed in a CT tube spectrum are due to: A) Electron-photon scattering in the detector B) Transitions of electrons between inner atomic shells of the target material C) Thermal radiation from the tube housing D) External magnetic fields influencing the beam Answer: B Explanation: Characteristic radiation arises when electrons fill vacancies in inner shells of the target atom, emitting photons with specific energies. Question 13. According to the Inverse Square Law, if the distance from the X-ray source to the patient is increased by 20 %, the intensity of the beam at the patient will: A) Increase by 20 % B) Decrease by 20 % C) Decrease by approximately 36 % D) Remain unchanged Answer: C Explanation: Intensity is inversely proportional to the square of the distance; (1/1.2²) ≈ 0.694, a ~30- 36 % reduction.
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Explanation: kVp determines photon energy spectrum; higher kVp yields more penetrating (higher quality) beams. Question 17. To reduce patient dose without compromising image quality, which combination of settings is most effective? A) Increase kVp and decrease mAs B) Decrease kVp and increase mAs C) Increase both kVp and mAs D) Decrease both kVp and mAs Answer: A Explanation: Raising kVp reduces beam attenuation, allowing a lower mAs (dose) while maintaining adequate contrast; this balances dose and noise. Question 18. In helical (spiral) CT, what does the term “pitch” refer to? A) The angle of the X-ray tube relative to the patient B) The ratio of table feed per rotation to total collimated beam width C) The slice thickness selected for reconstruction D) The frequency of the X-ray generator Answer: B Explanation: Pitch = table movement per rotation ÷ total collimated width; it influences scan speed, dose, and image resolution. Question 19. Automated exposure control (AEC) such as CARE Dose works by: A) Keeping kVp constant while varying mAs based on patient size B) Adjusting both kVp and mAs automatically to achieve a target image noise level C) Modulating the rotation speed of the gantry
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D) Changing the detector sensitivity during the scan Answer: B Explanation: AEC systems modulate tube current (and sometimes kVp) in real time to maintain consistent image noise, reducing unnecessary radiation. Question 20. CTDI (Computed Tomography Dose Index) measures: A) The cumulative dose received by the entire patient body B) The dose delivered to a standard phantom per single axial slice C) The effective dose after accounting for tissue weighting factors D) The dose to the radiology technologist during a procedure Answer: B Explanation: CTDI is measured in a standard acrylic phantom and reflects the dose for one slice, not the total patient dose. Question 21. DLP (Dose Length Product) is calculated by: A) Multiplying CTDIvol by the scan length (in cm) B) Adding the CTDI values of all slices C) Dividing CTDIvol by the number of detector rows D) Multiplying the patient’s weight by the CTDIvol Answer: A Explanation: DLP = CTDIvol × scan length; it represents the total radiation energy imparted along the scanned volume. Question 22. Which of the following is the most effective method for reducing scatter radiation to the technologist during a CT scan? A) Increasing the tube voltage
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Question 25. Which acquisition mode is most suitable for evaluating a rapidly moving heart? A) Axial (sequential) mode B) Helical mode with high pitch C) Prospective ECG-gated axial mode (step-and-shoot) D) Cine/shuttle mode without gating Answer: C Explanation: Prospective ECG-gated axial (step-and-shoot) acquires data only during a specific cardiac phase, minimizing motion artifacts in cardiac imaging. Question 26. When reconstructing a CT image, a thin slice thickness (e.g., 0.5 mm) primarily improves: A) Temporal resolution B) Spatial resolution in the z-axis and detection of small structures C) Radiation dose reduction D) Patient comfort during the scan Answer: B Explanation: Thinner slices reduce partial volume averaging, enhancing spatial resolution along the longitudinal axis and improving detection of fine details. Question 27. Filtered back-projection (FBP) differs from iterative reconstruction (IR) in that FBP: A) Requires multiple passes through the raw data to converge on an image B) Is computationally faster but more susceptible to noise
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C) Automatically reduces beam hardening artifacts without correction algorithms D) Provides superior image quality at low dose compared to IR Answer: B Explanation: FBP is a direct reconstruction method, fast but less effective at noise suppression; IR iteratively refines the image, reducing noise and artifacts. Question 28. Multi-planar reformation (MPR) allows the radiologist to view images in which planes? A) Only axial B) Axial, sagittal, and coronal planes C) Only sagittal and coronal D) Only 3-D volumetric renderings Answer: B Explanation: MPR reconstructs the volumetric data set into axial, sagittal, and coronal slices, providing comprehensive anatomical assessment. Question 29. Maximum intensity projection (MIP) is most useful for visualizing: A) Soft-tissue attenuation differences B) High-density structures such as contrast-filled vessels or calcifications C) Low-contrast lesions in the liver D) Bone marrow edema Answer: B Explanation: MIP projects the highest attenuation voxels onto a 2-D image, highlighting high-density structures like contrast-enhanced vessels.
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Explanation: High-density metal attenuates low-energy photons, leading to beam hardening and severe streaking around the implant. Question 33. Beam hardening artifact manifests on CT images as: A) Uniformly increased attenuation throughout the field of view B) A cupping effect where the center of a uniform phantom appears darker than the periphery C) Random speckle-like noise D) Ring-shaped patterns near the detector periphery Answer: B Explanation: Beam hardening preferentially removes low-energy photons, causing the central region of a homogenous object to appear less attenuated (cupping). Question 34. Partial volume averaging occurs when: A) The detector elements are miscalibrated B) A voxel contains more than one tissue type, averaging their attenuation values C) The patient’s heart is moving rapidly during acquisition D) The scan is performed with an excessively high pitch Answer: B Explanation: When a voxel spans multiple structures, the resulting attenuation is an average, potentially obscuring small lesions. Question 35. Which of the following parameters directly influences temporal resolution in cardiac CT? A) Detector row count B) Rotation time of the X-ray tube
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C) Pitch factor D) kVp setting Answer: B Explanation: Shorter rotation times reduce the time needed to acquire data for a given slice, improving temporal resolution for moving structures like the heart. Question 36. The most appropriate CT protocol for a patient with suspected acute pulmonary embolism includes: A) Non-contrast low-dose chest CT B) Contrast-enhanced CTA of the pulmonary arteries with bolus tracking C) High-resolution CT of the mediastinum only D) CT of the abdomen and pelvis with oral contrast Answer: B Explanation: CTA with intravenous contrast timed to the pulmonary artery opacifies emboli, providing the gold-standard evaluation. Question 37. In a CT brain perfusion study, which parameter reflects the cerebral blood volume (CBV)? A) Time-to-peak (TTP) B) Mean transit time (MTT) C) Cerebral blood flow (CBF) D) The area under the concentration-time curve for each voxel Answer: D Explanation: CBV is calculated from the integral of the contrast concentration–time curve, representing the total volume of blood in a voxel.
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Explanation: Intrathecal administration of iodinated contrast can provoke severe neurotoxic reactions in patients with known contrast allergy; it is an absolute contraindication. Question 41. In CT angiography of the coronary arteries, the “beta-blocker protocol” is employed to: A) Reduce patient anxiety during the scan B) Decrease heart rate, minimizing motion artifacts C) Increase contrast flow rate automatically D) Shorten the overall scan duration by 50 % Answer: B Explanation: Lowering heart rate (<65 bpm) with beta-blockers reduces cardiac motion, improving coronary artery visualization. Question 42. Which CT reconstruction slice thickness is typically used for lung cancer screening low-dose CT? A) 5 mm B) 2.5 mm C) 1 mm or less D) 0.2 mm Answer: C Explanation: Thin slices (≤1 mm) improve detection of small pulmonary nodules while maintaining low radiation dose. Question 43. The “artifact” known as “ring artifact” is most often caused by: A) Patient movement B) Miscalibrated detector elements leading to varying sensitivity
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C) Beam hardening from dense bone D) Excessive contrast concentration in the bloodstream Answer: B Explanation: Ring artifacts appear as concentric circles and arise from detector element defects or calibration errors. Question 44. Which of the following best describes the purpose of a “bolus tracking” technique in contrast-enhanced CT? A) To monitor patient blood pressure during injection B) To automatically trigger image acquisition when contrast reaches a predefined attenuation threshold in a target vessel C) To measure the total volume of contrast administered D) To adjust the kVp in real time based on contrast density Answer: B Explanation: Bolus tracking uses a region of interest to detect when contrast reaches a certain HU, initiating scan acquisition at optimal arterial enhancement. Question 45. In a CT abdomen with oral contrast, the preferred contrast agent is: A) Barium sulfate suspension B) Water-soluble iodinated contrast (e.g., diatrizoate) C) Gadolinium-based contrast D) Air Answer: B Explanation: Water-soluble iodinated agents are safe for the gastrointestinal tract and avoid the risk of barium peritonitis if leakage occurs.
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C) Sagittal only D) Multi-planar (axial, coronal, sagittal) reconstructions Answer: D Explanation: MPR in all three planes provides comprehensive anatomic detail, allowing precise assessment of fibroid location relative to the cavity. Question 49. When performing a CT-guided biopsy, the most important factor to verify before needle advancement is: A) Patient’s fasting status B) Exact trajectory avoiding vital structures on the planning images C) The brand of CT scanner used D) The contrast injection rate Answer: B Explanation: Safe needle placement requires a trajectory that avoids vessels, organs, and bones, minimizing complications. Question 50. Which of the following is a primary advantage of using a low-dose CT protocol for sinus imaging? A) Faster acquisition time B) Higher spatial resolution C) Reduced radiation exposure to the eyes and thyroid D) Elimination of the need for contrast Answer: C Explanation: Low-dose protocols lower radiation dose to radiosensitive structures (eyes, thyroid) while still providing sufficient diagnostic information for sinus disease.
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Question 51. In CT perfusion imaging of the brain, an increased mean transit time (MTT) with decreased cerebral blood flow (CBF) most likely indicates: A) Hyperemia B) Ischemic penumbra C) Normal tissue D) Hemorrhage Answer: B Explanation: Prolonged MTT and reduced CBF suggest delayed perfusion consistent with ischemic penumbra surrounding an infarct core. Question 52. Which of the following is a typical sign of contrast-induced nephropathy on laboratory testing? A) Sudden rise in serum creatinine within 48–72 hours after contrast exposure B) Decrease in blood urea nitrogen (BUN) C) Elevated liver enzymes D) Decreased serum potassium Answer: A Explanation: CIN is defined by an increase in serum creatinine ≥0.5 mg/dL or ≥25 % from baseline within 48–72 hours post-contrast. Question 53. The “pitch” value of 1.5 in a helical CT scan indicates: A) Table movement per rotation is 1.5 times the total collimated beam width
