Set of 16 prototype electrodes for applied potential tomography (APT), 1987.
© Science Museum / Science & Society Picture Library
This apparatus was developed by Profesor B H Brown at the Royal Hallamshire Hospital, Sheffield, England. In APT, now renamed electrical impedence tomography, electrodes attached to the body apply tiny electrical signals, which other electrodes pick up. Changes in the strength and timing of these signals are analyzed by computer to create an image. The electrodes are illustrated attached to a grapefruit which is standing in for a child's head and liquid is injected into the 'head' to mimic a brain haemorrhage.