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Practice Exam
Question 1. Which laboratory value is most important to review before administering iodinated contrast in a patient with suspected renal insufficiency? A) Serum calcium B) Blood urea nitrogen (BUN) C) Estimated glomerular filtration rate (eGFR) D) Serum albumin Answer: C Explanation: eGFR provides an estimate of kidney function and helps identify patients at risk for contrast‑induced nephropathy. Question 2. The primary purpose of obtaining informed consent before a CT scan with contrast is to: A) Reduce the radiation dose B) Ensure patient confidentiality C) Explain risks, benefits, and alternatives to the patient D) Verify the patient’s identity Answer: C Explanation: Informed consent requires that the patient understand the potential risks (e.g., allergic reaction), benefits, and alternatives before agreeing to the procedure. Question 3. Which of the following is a typical mild adverse reaction to iodinated contrast? A) Anaphylactic shock B) Nausea and vomiting C) Severe bronchospasm D) Cardiac arrest
Practice Exam
Answer: B Explanation: Mild reactions commonly include nausea, vomiting, or a warm sensation; severe reactions are less common. Question 4. The term “pitch” in helical CT scanning refers to: A) The number of detector rows activated per rotation B) The ratio of table travel per rotation to the total collimated beam width C) The angle of the X‑ray tube relative to the patient D) The slice thickness selected for reconstruction Answer: B Explanation: Pitch = table movement per rotation ÷ beam width; it influences scan speed and dose. Question 5. Which reconstruction algorithm is most effective at reducing image noise while allowing a lower radiation dose? A) Filtered back‑projection (FBP) B) Standard convolution kernel C) Iterative reconstruction (IR) D) Linear interpolation Answer: C Explanation: Iterative reconstruction models the imaging process and can achieve comparable image quality at reduced dose. Question 6. A patient undergoing a CT abdomen with oral contrast should be instructed to: A) Fast for 24 hours before the exam B) Drink the contrast 30 minutes prior to scanning
Practice Exam
B) Real‑time bolus tracking using a region of interest in the main pulmonary artery C) Manual timing based on patient weight D) Using a low‑flow rate of 1 mL/s Answer: B Explanation: Bolus tracking monitors contrast arrival and triggers the scan at optimal opacification. Question 10. Which artifact is most commonly caused by dense metal hardware within the scan field? A) Motion artifact B) Beam hardening streaks C) Partial volume averaging D) Ring artifact Answer: B Explanation: Metal attenuates low‑energy photons, causing beam hardening and characteristic streak artifacts. Question 11. The primary safety concern when scanning a pregnant patient with CT is: A) Contrast‑induced nephropathy B) Radiation exposure to the fetus C) Patient discomfort from the table D) Allergic reaction to iodinated contrast Answer: B Explanation: Ionizing radiation can cause fetal teratogenesis; CT is generally avoided unless benefits outweigh risks.
Practice Exam
Question 12. Which of the following best describes a “pan‑scan” protocol? A) A single‑phase CT of the abdomen only B) Whole‑body CT from head to pelvis performed in trauma patients C) Dual‑energy CT of the thorax D) Low‑dose CT for lung cancer screening Answer: B Explanation: A pan‑scan rapidly images the entire body to assess injuries in high‑energy trauma. Question 13. During a cardiac CT coronary angiography, heart rate control is important because: A) High heart rates increase contrast viscosity B) Motion artifacts are reduced when heart rate is < 65 bpm C) Low heart rates cause increased radiation dose D) It eliminates the need for ECG gating Answer: B Explanation: Lower heart rates reduce motion of coronary arteries, improving image sharpness. Question 14. Which parameter directly influences the spatial resolution of a CT image? A) Tube voltage (kVp) B) Slice thickness C) Pitch D) Detector element size Answer: D Explanation: Smaller detector elements capture finer detail, enhancing spatial resolution.
Practice Exam
Question 18. The purpose of a “dose‑modulation” system such as CARE Dose is to: A) Increase image noise for better detection of low‑contrast lesions B) Adjust tube current in real time based on patient attenuation C) Automatically select the optimal reconstruction kernel D) Reduce scan time by increasing pitch Answer: B Explanation: Automatic tube current modulation varies mA according to patient size, reducing dose while maintaining image quality. Question 19. A “partial volume” artifact occurs when: A) The detector elements are too large relative to the structure being imaged B) The patient moves during acquisition C) Low‑energy photons are preferentially absorbed D) The scan field of view exceeds the patient’s body size Answer: A Explanation: When a voxel contains multiple tissue types, the resulting average CT number can blur small structures. Question 20. Which of the following is the most appropriate method for protecting staff from scatter radiation during a CT exam? A) Wearing lead aprons and thyroid shields B) Standing directly behind the gantry during scanning C) Using only glass barriers without personal protective equipment D) Increasing the scan length to spread dose over a larger area
Practice Exam
Answer: A Explanation: Lead aprons and thyroid shields attenuate scatter radiation, reducing occupational exposure. Question 21. In CT perfusion imaging for acute stroke, the parameter “time‑to‑peak” (TTP) primarily reflects: A) Cerebral blood volume B) Cerebral blood flow C) Delay in contrast arrival to a tissue region D) Mean transit time of contrast through the brain Answer: C Explanation: TTP measures the time from contrast injection to maximum enhancement, indicating delayed perfusion. Question 22. Which of the following CT scan protocols utilizes a low‑kVp technique to improve contrast between iodine‑enhanced vessels and surrounding tissue? A) High‑resolution CT of the lung B) Pediatric abdominal CT C) CT angiography of the aorta D) Bone window CT of the spine Answer: C Explanation: Lower kVp increases the photoelectric effect, enhancing iodine attenuation and vessel conspicuity. Question 23. A patient with a known severe iodine allergy requires contrast‑enhanced CT. Which alternative contrast agent can be considered?
Practice Exam
Explanation: Beam hardening occurs when low‑energy photons are absorbed, leaving a higher‑energy beam that creates dark streaks near dense objects. Question 26. In a CT scan of the lumbar spine, the optimal patient positioning to reduce beam‑hardening artifacts from the pelvis is: A) Supine with arms above the head B) Prone with a pillow under the abdomen C) Supine with a knee‑support to slightly flex the hips D) Decubitus left lateral decubitus position Answer: C Explanation: Slight hip flexion moves the pelvis out of the scan field, reducing beam hardening near the lumbar vertebrae. Question 27. Which of the following statements about the “effective dose” (ED) is correct? A) It is measured in milligrays (mGy) B) It accounts for the varying radiosensitivity of different tissues C) It is identical to the CTDIvol value D) It is only relevant for pediatric patients Answer: B Explanation: Effective dose combines dose with tissue weighting factors to estimate stochastic risk. Question 28. During a CT-guided lung biopsy, the most important safety consideration is: A) Maintaining a high pitch to reduce scan time B) Ensuring the needle path avoids major vessels and airways C) Using the highest possible kVp for better image contrast
Practice Exam
D) Administering intravenous contrast before needle placement Answer: B Explanation: Avoiding vascular and airway injury reduces the risk of hemorrhage and pneumothorax. Question 29. Which CT acquisition mode provides isotropic voxels that enable high‑quality multiplanar reconstructions? A) Axial (sequential) scanning B) Helical (spiral) scanning with thin collimation C) High‑pitch helical scanning only D) Single‑slice continuous scanning Answer: B Explanation: Thin‑collimation helical scanning acquires overlapping data, yielding isotropic voxels suitable for MPR. Question 30. In CT of the chest, a “ground‑glass opacity” on the image most likely represents: A) Calcified nodule B) Air‑filled cavity C) Partial filling of alveoli or interstitial thickening D) Metal artifact Answer: C Explanation: Ground‑glass opacity indicates increased attenuation without obscuring bronchial and vascular markings, typical of partial alveolar filling or interstitial disease. Question 31. Which of the following is a correct statement regarding the use of a power injector for contrast delivery?
Practice Exam
Question 34. When performing a CT urography exam, the “excretory phase” is acquired: A) Immediately after contrast injection B) When contrast is visible in the renal cortex only C) Approximately 10–15 minutes after injection, when contrast is in the collecting system D) Only if the patient has a known ureteral obstruction Answer: C Explanation: The excretory phase highlights the renal pelvis, ureters, and bladder after contrast has been filtered. Question 35. In CT imaging, the “slice thickness” primarily affects: A) Temporal resolution B) Image noise and spatial resolution in the z‑axis C) The size of the field of view (FOV) D) The amount of contrast enhancement Answer: B Explanation: Thicker slices reduce noise but decrease spatial resolution along the z‑axis; thinner slices improve detail but increase noise. Question 36. Which of the following best describes a “ring artifact” in CT images? A) Circular streaks caused by miscalibrated detector elements B) Dark bands due to patient motion C) Bright linear artifacts from metallic implants D) Uniform low‑contrast area across the image
Practice Exam
Answer: A Explanation: Ring artifacts arise from detector element gain variations, producing concentric rings in the reconstructed image. Question 37. A patient with a pacemaker requires a CT scan of the chest. Which precaution is essential? A) Use a high‑kVp setting to minimize device heating B) Turn off the pacemaker before scanning C) Ensure the scan field does not include the device’s leads D) Use a low‑dose protocol and monitor the patient for arrhythmias Answer: D Explanation: Low‑dose protocols reduce electromagnetic interference; continuous monitoring is needed because CT can affect pacemaker function. Question 38. Which of the following is the most appropriate method to reduce motion artifact in a CT abdomen performed on a restless pediatric patient? A) Increase the pitch to 2. B) Use a sedation protocol under physician supervision C) Decrease the tube current (mA) D) Perform the scan in the prone position Answer: B Explanation: Sedation helps keep the child still, minimizing motion artifacts; pitch and mA adjustments do not eliminate motion. Question 39. In CT perfusion imaging, the parameter “cerebral blood flow” (CBF) is calculated from: A) The maximum attenuation value of the contrast bolus
Practice Exam
Question 42. Which of the following best explains why low‑kVp settings increase contrast between iodinated vessels and soft tissue? A) Higher photon flux at low kVp B) Increased photoelectric effect at energies near iodine’s K‑edge C) Reduced scatter radiation D) Lower tube current is required Answer: B Explanation: At lower kVp, X‑ray photon energies approach iodine’s K‑edge (~33 keV), enhancing attenuation and contrast. Question 43. In CT imaging, “pitch” values greater than 1.0 generally result in: A) Higher radiation dose and better image quality B) Lower radiation dose but potential increase in image noise C) No change in dose or image quality D) Decreased table speed Answer: B Explanation: Higher pitch reduces overlap of data, decreasing dose, but can increase noise if other parameters are unchanged. Question 44. The most common indication for a CT colonography (virtual colonoscopy) is: A) Acute abdominal pain B) Screening for colorectal cancer in average‑risk patients refusing optical colonoscopy C) Evaluation of small bowel obstruction D) Assessment of hepatic lesions
Practice Exam
Answer: B Explanation: CT colonography provides a non‑invasive alternative for colorectal cancer screening. Question 45. Which of the following is the correct definition of “modulation factor” in automatic exposure control? A) The ratio of the highest to lowest tube current used during a scan B) The percentage increase in image noise after dose reduction C) The number of detector rows activated per rotation D) The fixed value of mA set by the technologist Answer: A Explanation: Modulation factor describes the range of mA variation applied to adapt to patient attenuation. Question 46. In a CT brain perfusion study, the “penumbra” region is identified by: A) Normal cerebral blood flow and volume B) Decreased cerebral blood flow with preserved cerebral blood volume C) Increased mean transit time only D) Complete absence of contrast enhancement Answer: B Explanation: Penumbra shows reduced flow but maintained volume, indicating potentially salvageable tissue. Question 47. Which of the following contrast administration routes is NOT typically used for CT imaging? A) Intravenous peripheral line
Practice Exam
Question 50. Which of the following statements about “iterative reconstruction” (IR) is FALSE? A) IR can reduce image noise without increasing dose B) IR requires more computational time than filtered back‑projection C) IR completely eliminates all CT artifacts D) IR allows for lower mA settings while preserving diagnostic quality Answer: C Explanation: IR reduces noise but does not eradicate all types of artifacts (e.g., metal streaks). Question 51. A CT technologist notices a “halo” artifact around a high‑contrast object. This artifact is most likely caused by: A) Detector miscalibration B) Beam hardening from the object C) Patient motion during acquisition D) Over‑exposure of the detector Answer: B Explanation: Beam hardening leads to a dark halo surrounding dense objects due to preferential attenuation of low‑energy photons. Question 52. Which of the following best describes the purpose of “bolus tracking” in contrast‑enhanced CT? A) To monitor patient vital signs during injection B) To automatically trigger the scan when contrast reaches a predefined attenuation threshold in a region of interest C) To calculate the total volume of contrast administered D) To reduce the need for a power injector
Practice Exam
Answer: B Explanation: Bolus tracking ensures optimal timing of image acquisition relative to contrast arrival. Question 53. In CT angiography of the lower extremities, the “runoff” phase is obtained to evaluate: A) Arterial stenosis only B) Venous thrombosis C) Patency of the distal arterial tree and collateral circulation D) Bone mineral density Answer: C Explanation: The runoff phase images the peripheral arteries and collaterals after the main arterial phase. Question 54. Which of the following is a key consideration when selecting a reconstruction kernel for bone imaging? A) Use of a smooth kernel to reduce noise B) Use of a sharp/high‑frequency kernel to enhance edge definition C) Use of a medium kernel to balance contrast and spatial resolution D) Kernel selection does not affect bone visualization Answer: B Explanation: Sharp kernels increase edge definition, improving visualization of cortical bone details. Question 55. The term “effective mAs” (mAs_eff) in helical CT refers to: A) The product of tube current and rotation time divided by the pitch B) The tube voltage multiplied by the rotation time
