Medical imaging scans that create detailed images of the body’s internal structures are widely used in medicine. Doctors need them to detect and manage certain types of cancer, assess the extent of traumatic injuries, and diagnose and treat many other medical conditions. But the scans, known as computerized tomography (CT) scans, use x-rays that expose patents to cancer-causing radiation. And there is concern that a diagnostic tool that has become deeply embedded in American medicine is sometimes overused. A recent study estimated that up to 5% of all cancers may have been caused by CT scans