Before the invention of the EMI scanner it was impossible to produce detailed pictures of patients' brains. With this machine, doctors were first able to show the medical usefulness of scanning. It was the first type of scanner to be adopted in substantial numbers for medicine and set the pattern for other scanning technologies.

X-rays normally produce much better images of dense bodily structures, such as bones, than of brains or other soft tissues. To produce images of the separate parts of the brain it was necessary to introduce air or special liquids to the area. These were hazardous techniques. In addition, X-ray pictures are often confusing, since they are made up from overlapping shadows from different layers and structures in the body.

The brain scanner overcame this by using computing power to construct a picture from a series of 28,800 measurements made by a paired X-ray source and detector rotating around the patient. It took this first scanner several hours to produce its images.

The EMI scanner (computerised tomography - or CT scanner) was invented by Godfrey Hounsfield, who had previously been responsible for the first transistorised British business computer. Hounsfield worked for EMI, the British electronics and music company, which invested in new products after the success of Beatles' records, which were released on its Parlophone label. The greater experience of overseas companies in the medical technology business, however, forced EMI out of the market within a decade.

Inv. 1980-811