In computed tomography (CT), an x-ray source and x-ray detector rotate around a person. In modern scanners, the x-ray detector usually has 4 to 64 or more rows of sensors that record the x-rays that pass through the body. Data from the sensors represent a series of x-ray images taken from multiple angles all around the person. However, the images are not viewed directly but are sent to a computer. The computer converts them into images that resemble 2-dimensional slices (cross-sections) of the body. (Tomo means slice in Greek.) The computer can also construct 3-dimensional images from the recorded images.
CT used to be called CAT (computed axial tomography).