2016 AAPM Annual Meeting
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Session Title: Identifying Image Artifacts, Their Causes, and How to Fix Them
Question 1: Which of the following techniques is useful for helping to isolate the cause of an artifact in a flat field digital radiographic image?
Reference:AAPM Report 151 Ongoing Quality Control in Digital Radiography, Feb 2015, American Association of Physicists in Medicine, p. 20-21.
Choice A:Rotating the image receptor relative to the x-ray tube.
Choice B:Shifting the image receptor relative to the x-ray tube.
Choice C:Rotating the added filter.
Choice D:All of the above.
Question 2: The presence of a paired positive/negative density artifact in a digital radiographic image is most likely caused by which of the following?
Reference:Walz-Flannigan, A, D Magnuson, D Erickson, and B Schueler. “Artifacts in Digital Radiography.” AJR 198:156–161, 2012.
Choice A:Shift in position of debris in the beam present during gain calibration.
Choice B:Backscatter from exposure of objects located behind the detector.
Choice C:Residual signal from a previous exposure.
Choice D:Patient motion resulting from long exposure times.
Question 3: Which of the following is NOT likely to be a cause of a CT artifact?
Reference:Computed Tomography: Principles, Design, Artifacts, and Recent Advances (Chapter 7), Jiang Hsieh,  SPIE Press, Bellingham, WA, ISBN 0-8194-4425-1
Choice A:Miscalibrated detector.
Choice B:Contrast agent on the gantry window.
Choice C:Inappropriate window/level setting.
Choice D:Low mAs setting.
Choice E:Dental filling.
Question 4: In general, which of the following is NOT a reasonable response when a severe artifact is noticed on a patient scan?
Reference:Computed Tomography Quality Control Manual, 2012, American College of Radiology.
Choice A:Scan a uniform phantom.
Choice B:Call Service.
Choice C:Carefully review the patient images.
Choice D:Review the morning QC images.
Choice E:See if artifact is present on the next patient images.
Question 5: Which one of the following statements is TRUE?
Reference:Conti M. Why is TOF PET reconstruction a more robust method in the presence of inconsistent data? Phys Med Biol 2011;56:155-168
Choice A:Time-of-flight PET mitigates respiratory motion artifacts.
Choice B:Attenuation correction artifacts in PET/MR are not as prevalent as in PET/CT.
Choice C:A rigorous daily QA regimen will prevent scanner failures throughout the day.
Choice D:The failure of a PET detector creates focal areas of decreased uptake in a reconstructed PET image.
Question 6: Regarding “zipper” artifacts caused by radiofrequency interference, the appearance of the “zipper” or line extends in which direction:
Reference:DW McRobbie, EA Moore, MJ Graves, MR Prince, “MRI: From Picture to Proton,” 2nd edition, Cambridge University Press, pg. 103
Choice A:Anterior – posterior.
Choice B:Frequency encoding.
Choice C:Phase encoding.
Choice D:X-Y.
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