The Computed Axial Tomography Scan, or CAT, was developed by Cape Town physicist, Allan Cormack and his associate Godfrey Hounsfield. He provided the mathematical technique for the CAT scan, in which an X-ray source and electronic detectors are rotated about the body and the resulting data is analysed by a computer to produce a sharp map of the tissues within a cross-section of the body.
CAT-scan images allow the doctor to look at the inside of the body just as one would look at the inside of a loaf of bread by slicing it. This type of special X-ray, in a sense, takes "pictures" of slices of the body so doctors can look right at the area of interest. CAT-scans are frequently used to evaluate the brain, neck, spine, etc. CAT has revolutionised medicine because it allows doctors to see diseases that, in the past, could often only be found through surgery or by autopsy.
This invention resulted in a Nobel Prize in Physiology and Medicine.