A CT scan is a medical imaging study, in which, with the aid of X-rays and computer calculations, a cross-section is made of the part of the body that needs to be examined. A CT scan is best suited to create images of bones, brains, lungs, abdominal organs and veins.
The scan is made in a CT scanner, a tunnel-shaped X-ray device. In the tunnel is a ring, which rotates around the part of the body to be examined. Out of this ring comes an X-ray beam, which makes a new scan every few millimeters. It continues to do this until the entire study area has been photographed. The permeability of the examined body part for the used radiation is measured from a large number of angles around in thin ‘slices’. From the results, a computer builds a three-dimensional representation of the examined body part.
The patient is lying on an elongated treatment table and must remain as still as possible. Sometimes, a CT is made with contrast fluid. This fluid can be used to make clearer images of certain parts of the body (such as heart and blood vessels). Creating the scans is totally painless. The examination will take half an hour to an hour.
- The foundations of computer tomography were laid in 1963 by the American physicist Allan Macleod Cormack. Since computers had not enough computing power at that time, it took until 1969 before the British electrical engineer Godfrey Newbold Hounsfield could develop a first scanner.
- The term ‘tomography’ is derived from the Greek words tomos (slice) and graphein (writing, drawing).