Sir Godfrey Hounsfield invented the computed tomographic scanner, and thus made an incomparable contribution to medicine. An engineer, he conceived the idea of computed tomography during a weekend ramble in 1967. Initially it had nothing to do with medicine but was simply “a realisation that you could determine what was in a box by taking readings at all angles through it.”

Back in his workshop at EMI research laboratories in Hayes, Middlesex, he began work on a computerised device that could process hundreds of x ray beams to obtain a two-dimensional display of the soft tissues inside a living organism. By recording on sensors rather than x ray film and taking multiple pictures from a rotating photon source, a series of “slices” could be photographed that showed the different density of tissues. By making a series of such photographs at …