Representation of a Function by its Line Integrals, with Some Radiological Applications.

Cormack showed that changes in tissue density could be computed from x-ray data. Because of limitations in computing power no machine was constructed during the 1960s. Cormack's papers generated little interest until Godfrey Hounsfield and colleagues invented computed tomography, and built the first CT scanner in 1971, creating a real application of Cormack's theories. Cormack continued with "Representation of a Function by its Line Integrals, with Some Radiological Applications. II," Journal of Applied Physics 35 (1964) 2908-13.  

In 1979 the Nobel Prize in Physiology or Medicine was awarded jointly to Allan M. Cormack and Godfrey N. Hounsfield "for the development of computer assisted tomography."