Proton therapy was first proposed for cancer by the nuclear physicist Robert R. Wilson in the late 1940s. Since the 1950s, approximately more than 70,000 cancer patients throughout the world have been successfully treated with protons–-usually in physics research laboratories, where treatment options have generally been limited to specific tumor types and relatively few patients per year.
It is beneficial for patients that the local dose effect in conventional X-ray radiation can be applied to proton radiation with a factor of 1:1,1. The biological mechanism of effect of both types of radiation is essentially the same: separating electrons from a molecule – “ionization.” This leads, via intermediate stages, to damage of the nucleus and cell death during the next division of the cell.
Knowledge with regard to dose-effect relationships has been gained from 100 years of radiation therapy. The critical advantage of protons – especially with the scanning method used at the RPTC- is the outstanding dose distribution: concentration in the tumor – protection of healthy tissue.
Outside the USA and Japan, there are very few proton centers that offer a complete hospital setting, treatments for all areas of the body, and the ability to serve large numbers of patients. Centers that have been able to amass a great deal of experience are at Loma Linda University (near Los Angeles), and in Boston at the Massachusetts General Hospital of Harvard University, as well as at the renowned MD Anderson Cancer Center in Houston, Texas. In addition to the RPTC in Munich, the Hahn-Meitner-Institut (HMI) in Berlin is another center in Germany, although it only treats ocular tumors.
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 in Europe operate with the older scattering method using templates.