Sir Godfrey Newbold Hounsfield was an English electrical engineer who shared the 1979 Nobel Prize for Physiology or Medicine with Allan McLeod Cormack, for his part in developing the diagnostic technique of X-ray computed tomography, or, CT.

Hounsfield was the baby of a prominent farming family in Nottinghamshire, England, born in 1919. He was the youngest of five children (two brothers, two sisters.) He loved to tinker, fiddling with electrical gadgets and farm machinery throughout childhood. Hounsfield launched himself off haystacks in his homemade glider and reportedly almost killed himself using acetylene to see how high water-filled tar barrels could be propelled.

He was self-taught and received only honorary degrees, but his biggest idea changed radiology forever.

In 1969, Dr. James Ambrose, a London neuroradiologist, got a call from an engineer he had never met named Godfrey Hounsfield, of EMI laboratories. Inspired while on vacation, Hounsfield called to discuss his latest idea: reconstructing a 3D image of a box by considering it as a series of slices.

Hounsfield, who was already dismissed as a “crank” by many renowned radiologists, proposed an imaging device far superior to the commonly used X-ray machine, which produced fuzzy two-dimensional pictures of brain structures. Their meeting led to the first Computed Tomography (CT) scanner, a machine that revolutionized diagnostic medicine and the way we look inside the brain.

Hounsfield theorized that one could determine what was inside a box by taking X-ray readings at all angles around the object. He then set to work constructing a computer that could take input from X-rays at various angles to create an image of the object in “slices.” Applying this idea to the medical field led him to propose what is now known as computed tomography.

The Greek word tomos means “slice” or “section;” graphia means “describing.” Unlike an X-ray machine, which produces flat, 2D pictures of bone and tissues, Hounsfield’s device took multiple, thin photographic slices of objects, which could be later combined on a computer to create three-dimensional composite images.

Hounsfield was not yet aware of the work that Cormack had done on the theoretical mathematics for such a device. Hounsfield built a prototype head scanner and tested it first on a preserved human brain, then on a fresh cow brain from a butcher shop, and later on himself. Ambrose was convinced.

Hounsfield and Cormack combined to produce the first commercially viable CT scanner, called the “EMI-Scanner.” It was installed in Atkinson Morley Hospital in Wimbledon, England, and the first patient brain scan was done on October 1, 1971.  A woman in her early 40s was diagnosed with a brain tumor.

The original 1971 scan took 160 parallel readings through 180 angles, each 1° apart, with each scan taking a little over 5 minutes. The images from these scans took 2.5 hours to be processed by algebraic reconstruction techniques on a large computer.

In 1972, at the 32nd Congress of the British Institute of Radiology, Hounsfield and Ambrose first presented brain scans generated by CT in their talk, “Computerised Axial Tomography,” and changed medicine. Today, there are more than 9,000 scanners in the US and 45,000 worldwide. In 2004, Godfrey Hounsfield passed away at the age of 84, leaving one of the most important legacies in medical science history.