The man behind the CAT scanner

Abstract

Allan Cormack's story is worth telling, as that of one of three 'scientific' Nobel prize-winners to whom South Africa can lay some claim. Born in Johannesburg in 1924, he was educated at Rondebosch Boys' High School and at the universities of Cape Town (UCT) and Cambridge. Appointed to a lectureship in the Physics Department at UCT in 1950, Cormack spent the next six years honing his skills as a stimulating teacher and struggling, with very limited facilities, to establish his research reputation. In 1956 he was asked to act in a part-time capacity as a medical physicist at Groote Schuur Hospital in Cape Town. He started to think about the fundamentals which lay behind the problem of calculating in detail the dose distribution in human tissues subject to X-ray bombardment, and he realised immediately that the problem was a mathematical one. In 1957 he did a simple experiment in the Physics Department at UCT on a 'phantom' comprising a cylinder of aluminium surrounded by an annulus of wood, and the results confirmed the theory he had worked out for the case of spherical symmetry.