Ring artifact

Last revised by Dr Tristan Skalina on 30 Oct 2021

Ring artifacts are a CT phenomenon that occurs due to miscalibration or failure of one or more detector elements in a CT scanner. Less often, it can be caused by insufficient radiation dose or contrast material contamination of the detector cover 2. They occur close to the isocenter of the scan and are usually visible on multiple slices at the same location. They are a common problem in cranial CT.

Recalibration of the scanner will usually rectify the artifact. Occasionally detector elements need replacing which can be costly. The referring clinician should be notified that the concerning ring shadows are artifactual. 

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Cases and figures

  • Case 1: ring artifact
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  • Case 2: ring-artifact after reconstruction
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  • Case 3: streak, beam hardening and ring artifacts
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  • Case 4
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  • Case 5
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  • Case 6
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  • Case 7: partial ring
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  • Case 8
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  • Case 9
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  • Case 10
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  • Case 11
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  • Case 12
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  • Case 13: beam hardening and ring artifacts
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  • Case 14: on low dose CT
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