The computed tomographic (CT) scanner was conceived in 1967 by British engineer Sir Godfrey Hounsfield at EMI Central Research Laboratories using x-ray technology. The first patient studies were performed on Friday, October 1, 1971 in Wimbledon, England but it was not publicized until a year later.

Sir Godfrey Hounsfield continued to improve the quality of the devise and the first commercially available CT scanner was available in 1972. He co-invented the technology with physicist Dr. Allan Cormack.

However, it was the mathematical theory of Johann Radon way back in 1917, called “Radon transform,” that brought the technology to life. He demonstrated that the image of a three-dimensional object can be constructed from an infinite number of two-dimensional images of the object.

Another mathematical advancement that Hounsfield built on is the “Algebraic Reconstruction Technique,” which was formulated by Polish mathematician Stefan Kaczmarz in 1937. Stefan Kaczmarz proposed a simple method, called the Kaczmarz algorithm, to solve iteratively systems of linear equations Ax = b in Euclidean spaces. This procedure employs cyclic orthogonal projections onto the hyperplanes associated with such a system.

Both theories by Johann Radon and Stefan Kaczmarz were adopted by Hounsfield to create one of the greatest advancements in medical history.

In 1973, the first CT scanners were installed in the United States. Sir Hounsfield would go on to share the 1979 Nobel Prize in Physiology or Medicine with Allan M Cormack.

**History of computed tomographic (CT) scanner**