Allan M. Cormack Biography

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World of Anatomy and Physiology on Allan M. Cormack

Allan M. Cormack was a physicist whose theoretical analysis and experiments in nuclear and particle physics, computer tomography, and math led to his invention of a mathematical technique for computer-assisted x-ray tomography, which revolutionized noninvasive medical diagnosis.

Computerized axial tomography, otherwise known as the CAT scan, is a process by which x rays can be concentrated on specific sections of the human body at a variety of angles. Once this information is analyzed by a computer, it is combined to reproduce images of internal structures previously unviewable by medical technology. It is considered the most revolutionary development in the field of radiography since the discovery of the x ray by Wilhelm Conrad Röntgen in 1895.

Cormack was the first to analyze the possibility of such an examination of a biological system in 1963 and 1964, and to develop the equations needed for computer-assisted x-ray reconstruction of pictures of the human brain and body. In 1979, he was awarded the Nobel Prize for physiology or medicine, along with Godfrey Hounsfield, a British engineer who, independently of Cormack, developed the first commercially successful CAT scanning devices.

Allan MacLeod Cormack was born in Johannesburg, South Africa, the son of George and Amelia (MacLeod) Cormack, a civil service engineer and a teacher, respectively. The pair had emigrated from Scotland to South Africa prior to World War I, and after young Cormack's father died in 1936, the family settled in Cape Town, where Cormack attended the Rondebosch Boys High School. Here he developed a keen interest in astronomy, physics, mathematics, tennis, debating and acting. Although his first love was astronomy, upon enrolling at the University of Cape Town, Cormack chose the field of engineering, intending to obtain a degree that would allow him to earn a good living. However, within two years he changed his major to physics and completed a baccalaureate of science in 1944 and a Master of Science degree in the field of crystallography in 1945.

During the years that followed, Cormack pursued graduate studies in the field of theoretical physics at Cambridge University in England. Working as a research student in the university's Cavendish Laboratory, he studied radioactive helium under the tutelage of Otto Robert Frisch. He also attended lectures on quantum physics given by Nobel Prize winner Paul Dirac. While his study of physics did not lead him to a career in astronomy as he had anticipated, he remained avidly interested in that field. However, his studies of physics did lead him to meet Barbara Jeanne Seavey, an American whom he met in the lecture hall and married on January 6, 1950. With little money, he returned to South Africa from Cambridge to resume his position as a lecturer in physics at the University of Cape Town, where he would remain until 1956. It was during this period that he was asked to serve a six-month service as resident medical physicist in the radiology department at the Groote Schuur Hospital in Cape Town, where he supervised the use of radioisotopes, as well as the calibration of film badges used to measure hospital workers' exposure to radiation.

At Groote Schuur, Cormack witnessed how radiation was being used in the diagnosis and treatment of cancer patients. Baffled by deficiencies in the technology used for such procedures, the experience helped plant the seeds of theoretical analysis that would lead Cormack to develop the CAT scan equations and techniques that would earn him the Nobel Prize in 1979. "I asked myself," he told the New York Times following the announcement of the prize, "how can you give a dose of radiation if you don't know the material through which it has to pass""

This simple question led Cormack to a series of experiments and analyses, the results of which were two papers published separately between 1963 and 1964 in the Journal of Applied Physics. By this time, Cormack was also conducting theoretical physics research in Boston on subatomic particles, following a 1956 Harvard University sabbatical as a Research Fellow, where he worked in the cyclotron laboratory under director Andreas Koehler.

Following a brief return to Cape Town in 1957, Cormack returned to the United States, accepting a post as assistant professor of physics at Tufts University in Medford, Massachusetts. Between 1956 and 1964, most of his research in connection with the development of computerized axial tomography was conducted on his own time. Indeed, neither of his two Journal of Applied Physics papers met with significant response, despite the fact that they proved the feasibility of his method for producing images of heretofore unviewable or barely viewable cross sections of the human body.

Cormack was naturalized as a citizen of the United States in 1966, and continued his academic career and his research in particle physics at Tufts. He was eventually promoted to associate, and then full professor of physics, serving as chairman of the physics department from 1968 to 1976. Meanwhile, Hounsfield was independently coming to conclusions similar to Cormack's, and developed the first CAT scanner as early as 1972.

In 1979, Cormack and Hounsfield were awarded the Nobel Prize for physiology or medicine for their joint, but independent development of CAT scan theory and technology. At the time, their selection as recipients of the prize was considered highly unusual. Unlike previous Nobel recipients, neither Cormack nor Hounsfield held a doctorate in medicine or science; further, their discovery was awarded the prize only after the Nobel Assembly vetoed the first choice of the selection committee, reportedly due to a split between factions, with one side favoring discoveries in basic science and the other, those in applied science. Finally, it was highly unusual that the two men had never met or worked together, yet had worked on the same invention concurrently. The story of their simultaneous research is a classic example of independent scientific discovery.

In 1980, Tufts appointed Cormack to university professor, its highest professorial rank, and awarded him an honorary doctoral degree. In 1990, as one of several scientists receiving the National Medal of Science, Cormack was recognized by President George Bush. Bush was quoted in the New York Times, lauding the group of scientists as "real life pioneers who press the very limits of their fields." Cormack is a member of the National Academy of Science and the American Academy of Arts and Sciences, and is a fellow of the American Physical Society.

Cormack, who died in 1998, was remembered by his friends as a man with a potent sense of humor, with passionate interests in tennis, swimming, sailing, rock climbing, music, and, as always, astronomy.