The first detailed picture of a living brain was taken by a CT scanner in 1971. CT stands for computerized tomography. CT scanners, a type of X‑ray machine, became important for diagnosis within hospitals during the late 20th century. They are sometimes called CAT (computer-assisted tomography) scanners.

Unlike X‑ray machines, CT scanners send multiple X‑ray beams through the body at different angles. This is called tomography. Detectors inside the machine record how the beams pass through sections of the body. A computer uses complex mathematics to process these measurements and construct an internal image of the body, displayed on a monitor.

The first CT scanner was built by Godfrey Hounsfield in 1971. It was designed to only take pictures of the brain, and revealed a brain tumour in a 41-year-old female patient. Tomographic techniques had been used since the 1930s, but Hounsfield was the first to combine an X‑ray machine and a computer. In 1975 the first whole-body CT scanner was built. CT scanners are now used to take pictures of virtually any part of the body.

CT scanning owed a lot to pop band The Beatles in the 1960s. Hounsfield worked for EMI, the company that owned The Beatles’ music. EMI used the profits made from Beatles records to invest in Hounsfield’s scanning technology. In 1979, Hounsfield was awarded a Nobel Prize for his work.