Proton therapy was first proposed for cancer by the nuclear physicist Robert R. Wilson in the late 1940s. Since the 1950s, approximately 40,000 cancer patients throughout the world have been successfully treated with protons–-usually in physics research laboratories, where the treatment options have generally been limited to specific forms of tumours and relatively few patients per year.

Only the USA and Japan currently have proton centres that offer a complete hospital setting and treatments for all areas of the body and large numbers of patients. These include the centres at Loma Linda University (near Los Angeles) and in Boston at the Massachusetts General Hospital of Harvard University. Other centres are currently under construction, such as at the MD Anderson Cancer Center in Houston, Texas. Apart from the RPTC in Munich, the Hahn-Meitner-Institut (HMI) in Berlin is another centre in Germany, although it only treats tumours of the eye.

Except for the RPTC and the research institutes Paul-Scherrer (PSI) in Villingen/Switzerland and the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, all the systems operate with the older scattering method using templates.