In the early 1970s, Sir Godfrey Hounsfield’s research produced the first clinically useful computed tomography (CT) scans. • Original scanners took approximately 6 minutes to perform a rotation (one slice) and 20 minutes to reconstruct (Fig. 1a). Despite many technological advances since then, the principles remain the same. • On early scanners, the tube rotated around a stationary patient, with the table moving to enable a further acquisition. The machine rotated clockwise and counter-clockwise as power was supplied via a cable. • Modern-day helical or spiral scanners obtain power via slip ring technology, thus allowing continuous tube rotation as the patient moves through the scanner automatically (Fig. 1b). This allows a volume of data to be acquired in a single rotation, with the benefits of faster scanning, faster patient throughput and reduced patient movement artefacts. • New multi-slice scanners use existing helical scanning technology, but have multiple rows of detectors to acquire multiple slices per tube rotation. The faster imaging with multi-slice scanners allows a larger volume of coverage and multiphase scanning during intravenous contrast administration (Fig. 2). This, coupled with improved spatial resolution, allows organ- specific as well as vascular assessment, leading to the advent of CT angiography and virtual endoscopy. • Advanced computer processing power allows reconstructive techniques, such as threedimensional and multiplane reformatting, providing us with additional tools with which to improve diagnostic accuracy and aid clinical management.