A liking for gadgets and X-rays
British scientists were fascinated with the X-rays that German physicist Wilhelm Röntgen discovered in 1895.
In 1915, William Lawrence Bragg and his father Lawrence Bragg pioneered X-ray crystallography. (At the age of 25, William Lawrence became the youngest person ever awarded the Nobel Prize. Details in the Ingenious Timeline.)
In Cambridge after World War II, X-ray crystallography became key to unpacking the structures of nucleic acids and proteins and to the development of generic and affordable drugs.
Another Brit interested in X-rays was Godfrey Hounsfield. In the 1950s, out walking in the country, he had one of those ha-ha moments of which scientists are so fond.
By then Hounsfield had learned the basics of electronics and radar as a Royal Air Force volunteer reservist during the war, had attended Faraday House Electrical Engineering College in London, and had worked for a decade at EMI Ltd. where he helped to design an all-transistor computer.
Hounsfield’s idea was to build a gadget that could take input from X-rays at various angles to create an image of the object in "slices". Since X-rays are absorbed differently by tissues of varying density within the body, Hounsfield had to link his scanner to a computer that could compile the data into a 3D image. South African Allan Cormack was engaged in theoretical work on a similar device, and he and Hounsfield shared the Nobel Prize in medicine in 1979 for computed tomography, which has transformed investigative medicine.
In the 1980s, Peter Mansfield took a different approach to medical imaging. Mansfield had dropped out of school at 15, worked at a printing company and joined the Army before getting serious about his education. After earning a PhD in Physics he collaborated with Paul Lauterbur of the University of Illinois on magnetic resonance imaging, known as the MRI.
Mansfield developed a mathematical model that analysed signals from inside the human body in response to a strong magnetic field. He also developed echo-planar imaging, which allows images to be collected many times faster than previously possible. This made MRIs feasible.
Doctors and patients greatly benefitted from these inventions, but whether medical imaging is the greatest of medical milestones, I leave to you to decide. if you like, you can vote in the BMJ poll here.