2007 Radiology Exam - Artifacts Case 2

2007 Technical Errors and Artifacts Case 2

Objective of the Case
1. Identify the artifact or problem
2. Describe how the artifact/problem may have occurred
3. Discuss how to avoid the artifact/problem or if inevitable, how this would affect interpretation of the study
4. Discuss how this particular artifact would affect interpretation of the study.

Information provided to Candidate
1. Written instructions above.
2. The candidate was provided with the image below printed on laser film and informed that the image below was obtained with a CT scanner. They were directed to specifically address the thin, alternating high and low density ring-shaped artifact on the image.

See image below. Click to enlarge.

Findings Expected from Candidate
1. Identify artifact: CT ring artifact
2. The artifact is caused by failure of, damage and/or miscalibration of a detector in a 3rd generation CT scanner.
3. The candidate was expected to advise that a service visit would be necessary to facilitate identification of the damaged detector and repair of the CT scanner.
4. The candidate should relay that the artifact obscures and distorts regional anatomy resulting in this case in a non-diagnostic study, and that ring artifacts if small might mimic pathology.

Summary of Overall Candidate Performance
The question was worth a total of 6 points. The average score was 5.78/6.0 or 96%.