ABSTRACT
The first clinical CT scans of the brain were obtained in 1972 on a prototype CT scanner developed by Hounsfield. The first clinical scanner, the EMI Mark I scanner, was introduced in 1973. The Nobel prize in medicine was awarded to Sir Godfrey Hounsfield and Alan Cormack in 1979 for the development of computer-assisted tomography, underscoring the impact of this achievement on clinical medicine. Improvements in design led to slip ring technology and thus helical or spiral scanning, first introduced in 1975 at Varian and then reintroduced with a more practical design in 1985 and 1987 by Toshiba and Siemens, respectively. Where the EMI Mark I scanner required approximately 5 minutes for the acquisition of one imaging section, spiral scanners could cover several centimeters in less than 60 seconds, obtaining nearly isotropic resolution over a small field of view but at the expense of tube heating (1).
