MODEL RELEASED. CT scanning. Radiographer watching a patient undergoing a CT scan from inside the control room. Computed tomography (CT) is a diagnostic technique that sends small doses of X-rays through the body at different angles to produce cross-sectional images of the area scanned. The patient, and the bed on which he is lying, will be passed through the hole in the scanner. A computer compiles the X-ray data into multiple image slices. CT scans are widely used to locate tumours, as they are good at distinguishing soft tissue from bone.