Sir Godfrey Hounsfield pioneered a leap forward in medical diagnosis: computerized axial tomography, popularly known as the "CAT scan." Ushering in a new and sometimes controversial era of medical technology, Hounsfield's device allowed a doctor to look inside a patient's body and examine a three-dimensional image far more detailed than a conventional x ray. The importance of this advance was recognized in 1979, the year Hounsfield received the Nobel Prize for physiology or medicine.

Godfrey Newbold Hounsfield was born in Newark, England, the youngest of five children of a steel-industry engineer turned farmer. Hounsfield's technical interests began when, to prevent boredom, he began figuring out how the machinery on his father's farm worked. From there he moved on to exploring electronics, and by his teens was building his own radio sets. He graduated from London's City and Guilds College in 1938 after studying radio communication. When World War II erupted...