Medical-imaging modalities, including radiology, nuclear medicine, and ultrasound, allow clinicians to image the body for the examination, diagnosis, and increasingly treatment of medical conditions.Medical imaging has progressed rapidly as a result of technological and computing advances,and it is estimated to account for 5–10% of current healthcare expenditure. Factors driving the expansion of medical-imaging utilization include the increased availability and functionality of imaging modalities, patient demand for more examinations and an aging population dealing with complex conditions.3 As service use increases, concerns about the appropriate use of medical-imaging services, their costs, and their contribution to the quality of patient care have been raised. Some estimates have suggested that 30–40% of all imaging examinations in the USA may be inappropriate