What type of artifact is produced by patient motion during a CT scan?

Motion artifact is indeed the correct term for the type of distortion observed in CT images when a patient moves during the scanning process. This artifact arises because the CT scanner captures images while the patient's position is not static, causing blurring or streaking on the final images.

When a patient moves, it creates discrepancies in the data collected by the detectors, leading to inaccuracies in the reconstructed image. The resultant motion artifact can sometimes appear as either a blurring effect or ghosting, depending on the nature of the movement. This can significantly affect the diagnostic quality of the scan and make it difficult to interpret the results correctly.

Other types of artifacts mentioned in the options, such as ring artifacts, beam hardening, and out-of-field artifacts, are caused by different factors unrelated to patient motion. Ring artifacts are typically associated with malfunctioning detectors, beam hardening occurs due to variations in tissue density, and out-of-field artifacts arise when parts of the anatomy being scanned fall outside the optimal detectable range of the imaging system. Understanding the specific causes of these artifacts helps in distinguishing them from motion artifacts and underscores the importance of patient cooperation during imaging procedures.