CT scan, conceptual computer artwork. Computed tomography (CT), also known as computed axial tomography (CAT), is a medical imaging technique where an image of internal organs is built up by scanning sections through the body. By combining a series of lines, a 2D image can be created, and it is possible to generate a 3D model from a series of 2D images. This scan is of a brain, where the lines represent the sequence of sections through the brain.