Radiology for Residents

Invention of the CT-Scanner


While on an outing in the country, Hounsfield came up with the idea that one could determine what was inside a box by taking X-ray readings at all angles around the object. He then set to work constructing a computer that could take input from X-rays at various angles to create an image of the object in "slices". Applying this idea to the medical field led him to propose what is now known as computed tomography. At the time, Hounsfield was not aware of the work that Cormack had done on the theoretical mathematics for such a device.

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The prototype CT scanner


Hounsfield built a prototype head scanner and tested it first on a preserved human brain, then on a fresh cow brain from a butcher shop, and later on himself. In September 1971, CT scanning was introduced into medical practice with a successful scan on a cerebral cyst patient at Atkinson Morley Hospital in Wimbledon, London, United Kingdom. In 1975, Hounsfield built a whole-body scanner.

The first clinical CT scan on a patient took place on 1st October 1971 at Atkinson Morley's Hospital, in London, England. The patient, a lady with a suspected frontal lobe tumour, was scanned with a prototype scanner, developed by Godfrey Hounsfield and his team at EMI Central Research Laboratories in Hayes, west London. The scanner produced an image with an 80 x 80 matrix, taking about 5 minutes for each scan, with a similar time required to process the data.

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The first clinical scan: Atkinson Morley's Hospital, October 1971