Allan MacLeod Cormack was a South African American physicist who won the 1979 Nobel Prize in Physiology or Medicine for his work on X-ray computed tomography (CT). He was born on February 23, 1924 in Johannesburg, South Africa. He received his B.Sc. in physics in 1944 from the University of Cape Town and his M.Sc. in crystallography in 1945 from the same institution. He was a research student at Cambridge University from 1947–49. After graduating from the University of Cape Town in 1944 Cormack pursued advanced studies there and at the University of Cambridge. He was a lecturer at Cape Town from 1950 to 1956 and then, after a year’s research fellowship at Harvard University, became assistant professor of physics at Tufts University. His main research at Tufts centred on the interaction of subatomic particles. He advanced to full professor in 1964, was chairman of the department from 1968 to 1976, and retired in 1980. He became a U.S. citizen in 1966. In 1990, he received the National Medal Of Science. He died on May 7, 1998 in Massachusetts, United States.