ARRT Computed Tomography Examination Practice Test
Computed tomography practice covers how scanners acquire and reconstruct cross-sectional images and how technologists assess image quality and patient safety. The available questions sample CT system components, Hounsfield units, slice-location information, region-of-interest measurements, and image-uniformity checks, alongside decisions about contrast use and equipment limits.
Exam overview
About the ARRT Computed Tomography Examination Exam
CT work involves coordinating patient positioning and scan parameters with the diagnostic task while monitoring radiation exposure and contrast-related risk. Questions in this practice bank touch on the detector array’s conversion of transmitted x-rays into signals, slip-ring operation during continuous gantry rotation, and bow-tie filtration across the scan field. Other items address interpreting CT numbers, using ROI standard deviation as a measure of pixel-value variation, and identifying changes in uniformity across a phantom image. Safety scenarios include checking the table’s manufacturer-rated load and responding appropriately to a documented severe immediate reaction to iodinated contrast. These concepts connect equipment function and quality control to the technologist’s decisions before acquisition and during image review.
Sample Practice Questions
Review a selection from this exam's published US Practice Tests practice bank.
A CT table has a maximum patient weight limit stated by the manufacturer. Why must staff consider this limit before scanning?
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Correct answer: AThe table and gantry have specified mechanical limits. Checking them supports safe equipment operation and helps staff plan positioning and an appropriate imaging approach before the patient is placed on the table.
What is a principal reason for using intravenous iodinated contrast in CT when clinically indicated?
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Correct answer: AIodine attenuates x-rays strongly, so intravenous administration can enhance blood vessels and perfused tissues and improve visualization of selected anatomy or pathology. The timing and use of contrast depend on the clinical indication and patient factors.
What is the main purpose of a CT gantry’s slip-ring technology?
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Correct answer: ASlip rings provide electrical power and signal connections while the gantry rotates continuously. This enables continuous rotation used in helical scanning without cables wrapping around the gantry.
A CT technologist is reviewing a series with a slice location that is 15 mm cranial to the prior image. Which information most directly identifies the slice’s position along the patient axis?
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Correct answer: AThe z-axis location coordinate identifies an image’s position along the longitudinal, or head-to-foot, direction. Window settings, kernel, and bit depth describe other image properties rather than slice location.
A CT detector converts transmitted x-ray energy into electrical signals. What is the primary function of the detector array?
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Correct answer: AThe detector array measures transmitted x-ray intensity after the beam passes through the patient. These measurements are used to form projection data for image reconstruction.
A patient has a documented prior severe immediate reaction to iodinated contrast. Before a contrast-enhanced CT examination, what is the most appropriate action?
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Correct answer: BA prior severe immediate reaction is important risk information. The responsible clinician should be informed so the need for contrast, potential alternatives, and any risk-mitigation plan can be assessed under local policy.
A CT image shows a circular region of interest (ROI) placed within uniform soft tissue. What does the ROI standard deviation of pixel values primarily indicate?
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Correct answer: BThe standard deviation describes how dispersed the pixel values are around their mean. In a uniform region, it is commonly used as a measure related to image noise; the mean instead represents average attenuation.
How to use this practice test
The free practice bank contains 50 published questions; each session presents up to 20 questions selected at random. Submit a session to see results, then use missed or uncertain items to identify whether the gap concerns scanner physics, image evaluation, or patient-safety decisions.
Preparation tips
- Review how detector arrays, slip rings, and bow-tie filters contribute to CT acquisition, and distinguish each component’s role.
- Practice interpreting Hounsfield values and ROI standard deviation, including what a uniform phantom’s center-to-edge CT-number change suggests about image quality.
- For contrast scenarios, connect a history of severe immediate reaction to a cautious pre-examination response rather than treating contrast as routine.
- Before reviewing scan setup cases, check how patient weight limits, slice-location coordinates, and patient-axis orientation affect safe and accurate acquisition.