Georges Charpak’s particle detector led to low-dose X-rays

Person: Georges Charpak
Lived: 1924–2010
Field: Particle physics, detectors
From: Polish-born French

The story

Georges Charpak was born in 1924 to Jewish parents in Dąbrowica in eastern Poland and grew up in Paris. As a teenager he joined the French Resistance, was imprisoned by the Vichy authorities in 1943 and deported to Dachau in 1944, surviving until the camp’s liberation. After the war he became a physicist and in 1959 joined CERN.

In 1968 he invented the multiwire proportional chamber, a gas-filled box strung with many fine wires, each with its own amplifier and linked to a computer. It recorded particle tracks about a thousand times faster than earlier photographic methods and transformed particle physics, earning him the 1992 Nobel Prize in Physics. From the start he looked for uses in medicine and biology. Because a gas detector can register individual X-ray photons efficiently, it can make a good image with far less radiation than film. In 1989 he founded a company, Biospace Instruments, to develop his detectors for biomedical uses.

Working with the paediatric orthopaedic surgeon Jean Dubousset and a team of physicists, engineers and radiologists, Charpak helped develop EOS, a system operational from 2003 that scans a standing patient from head to feet, from the front and the side at the same time. It was designed with children in mind, particularly those with scoliosis, a curvature of the spine that needs repeated X-rays as a child grows. Each X-ray adds to the dose received by sensitive organs such as bone marrow and breasts.

In a study of children with scoliosis, the French National Academy of Medicine reported that EOS reduced the radiation dose of standard front and side spine images by about eight to ten times compared with conventional radiography. It also produced three-dimensional reconstructions of the skeleton as accurate as those from CT scans, at doses reported to be several hundred times lower, and with the patient standing in a natural, weight-bearing position rather than lying down.

Why it matters

EOS imaging, built on Charpak’s detector, lets children and adults who need repeated skeletal X-rays receive a fraction of the radiation of conventional methods.

About Georges Charpak

Resistance fighter and Dachau survivor whose wire chamber transformed particle physics and led to low-dose X-ray imaging; he also brought hands-on science to French primary schools. Nobel Prize 1992.

Read the full profile

Georges Charpak

1924–2010 · Particle physics, detectors

View profile →