A computed axial tomography / computed tomography (CAT / CT) scan uses X-rays to make detailed pictures of structures inside of the body.

During the test, you will lie on a table that is attached to the CAT / CT scanner, which is a large doughnut-shaped machine. The CAT / CT scanner sends X-rays through the body area being studied. Each rotation of the scanner provides a picture of a thin slice of the organ or area.

Patients are often asked to avoid food, especially when contrast material is to be used. Contrast material may be injected intravenously, or administered by mouth in order to increase the distinction between various organs or areas of the body. Therefore, fluids and food may be restricted for several hours before the examination.

If the patient has a history of allergy to contrast material (such as iodine), the requesting physician and radiology staff should be notified. All metallic materials and certain clothing are removed because they can interfere with the clarity of the images.

Patients are placed on a movable table, and the table is slipped into the center of a large donut-shaped machine which takes the X-ray images around the body. The actual procedure can take from a half-hour.

It is important during the CAT Scan / CT scan procedure that the patient minimize any body movement by remaining as still and quiet as possible. This significantly increases the clarity of the X-ray images.

The CAT / CT scanner is programmed to tell the patient when to breathe or hold his/her breathe during scans of the chest and abdomen. If the patient experiences any problems during the CAT Scan / CT scan, the technologist should be informed immediately. The technologist directly watches the patient through an observation window during the procedure, and there is an intercom system in the room for added patient safety.