A CT (computed axial tomography) scan, or CAT scan, is a noninvasive or minimally invasive test that uses a rotating x-ray device to create detailed cross-sectional images (or slices) of different body parts. It may be performed alone or with the use of a special dye, called a contrast medium.

CT scans are used to diagnose a number of injuries, conditions and diseases, including internal injuries, muscle and bone disorders. Various types of CT scans may be performed, taking images of the whole body, abdomen, chest, head, sinus cavities or spine.

CT scans are generally performed by a radiology technician in a hospital or outpatient clinic. During the test, the patient lies down on a scanning table, which slides slowly into a short, open-ended tunnel. If a contrast medium is used, it can be administered orally (by mouth), through an enema or injected into a vein. The test is painless except for brief discomfort that may be felt if an injection is used.

The length of a CT scan varies from a few minutes to an hour, depending on the type of equipment used and the requests of the physician. Patients normally have to remain still for most of the time during a CT scan. Patients can usually return to normal activities after the test.

Radiation levels used with CT scans are higher than those used with x-rays. However, the levels are known to be well within safety limits, except for abdominal or chest CT scans during pregnancy. Although some patients may be concerned about radiation exposure from a CT scan, the potentially life-saving benefits of the information obtained from the test outweigh the risks for most patients.