Definition: A computed tomography scan is a study that uses a series of x-rays to create image "slices" of the body. This type of study is commonly called a CAT scan, but the terminology CT scan is preferred. The "A" in CAT refers to "axial," or computed axial tomography. Axial is an orientation of images, and at one point in time, it was the only orientation available. With modern computing, many orientations of the imaged (including 3D) can be obtained, so most doctors refer to CT scans.
During a CT scan, the patient is on a table that has a doughnut shaped device at one end. This device contains an x-ray that takes images of the body from different angles. A computer integrates these images to create a two-dimensional (and sometimes 3D) image of the body. The images represent slices of the body, and are usually completed in a series with about one slice per centimeter.