n a CT scan, multiple x-ray images are taken from different directions. The x-ray data are then fed into a tomographic reconstruction program to be processed by a computer. The deduction of the tissue structure from the x-rays is done using a technique first obtained in 1917 by Johann Radon.
Radon, an Austrian mathematician, was studying the mathematical properties of the operation that we now call the Radon transform. He was motivated by purely theoretical interest, and could not have anticipated the great utility of his work in the practical context of CT. Reconstruction techniques have grown in sophistication, but are still founded on Radon’s work.