Computed tomography (CT) is a modern imaging tool that combines X-rays with computer technology to produce a more detailed, cross-sectional image of your body. A CT scan lets your doctor see the size, shape, and position of structures that are deep inside your body, such as organs, tissues, or tumors. Tell your doctor if you are pregnant before undergoing a CT scan.

You lie as motionless as possible on a table that slides into the center of the cylinder-like CT scanner. The process is painless. An X-ray tube slowly rotates around you, taking many pictures from all directions. A computer combines the images to produce a clear, two-dimensional view on a television screen.

You may need a CT scan if you have a problem with a small, bony structure or if you have severe trauma to the brain, spinal cord, chest, abdomen, or pelvis. As with a regular X-ray, sometimes you may be given barium sulfate or a dye to make certain parts of your body show up better. A CT scan costs more and takes more time than a regular X-ray, and it is not always available in small hospitals and rural areas.