What may result in a ring artifact on a CT image?

A ring artifact on a CT image typically occurs due to inaccuracies in the detector system, specifically when there is a miscalibration of a detector element. In essence, this miscalibration causes a particular detector to receive different amounts of radiation compared to its neighbors, leading to inconsistencies in the data acquisition process. As the CT scanner rotates around the patient, these inconsistencies manifest as circular artifacts on the resulting image, resembling rings. This type of artifact is particularly noticeable in images where uniform structures are represented, as the deviations from the expected signal will create recognizable patterns that degrade image quality and hinder diagnostic interpretation.

In contrast, averaging multiple tissue types into one voxel would lead to more uniform representation and not typically cause a ring artifact. A large display field-of-view does influence the generated image in terms of spatial extent but does not inherently cause ring artifacts. Lastly, leaving the patient's arms in the exposure field could interfere with image quality, leading to other types of artifacts, such as beam hardening or scatter artifacts, but would not specifically generate the ring artifact associated with detector calibration issues.