CT scanner. 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 lies on the bed (centre) and is 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. This is a Siemens SOMATOM Sensation CT scanner, which was first introduced in 2003. Photographed at the Royal Hospital for Sick Children, Edinburgh, UK.