Computed tomography (CT) imaging is also known as CAT-scanning (computed axial tomography). CT was invented in 1972 by British engineer Godfrey Hounsfield (1919-2004) and South African-born physicist Allan Cormack (1924-1998). In 1979, they were awarded the Nobel Prize of Physiology and Medicine for their contribution to medicine and science.

The first CT-scanner developed by Hounsfield took several hours to acquire raw data for a single scan and it took days to reconstruct a single image from this raw data. The latest multi-slice CT-systems provide up to four slices of data in about 350 ms and reconstruct a 512×512 matrix image from millions of data points in less than a second. The most advanced multi-slice CT-system is able to scan the entire chest (forty 8 mm slices) in five to ten seconds. In its 25 years of existence, computed tomography has undergone enormous progress as to speed, patient comfort resolution and reduction of X-ray doses.