Latest Developments in Proton Therapy

The intent of this review is to give insight in the present status and on the prospective future of proton therapy. The major point of reference is conventional therapy with photons. Traditional radiotherapy is showing nowadays a very rapid progress using advanced dynamic beam delivery techniques and sophisticated computer algorithms for treatment planning. The new fashionable concepts in medical physics are "Inverse planning" and "Intensity modulated therapy". Proton therapy compared to photon therapy has the advantage of the localisation of dose in depth, but implies higher costs for the accelerator and beam lines. Within the field of proton therapy the competition is between the established traditional beam delivery techniques using passive scattering and the new methods based on magnetic beam scanning. The innovative developments are compact gantries dedicated to beam scanning capable of delivering "intensity modulated proton therapy". Despite many uncertainties, proton therapy is steadily gaining in socio-economical importance. About 10 hospital-based proton or heavy ion therapy facilities are now under construction or already available in the U.S.A. and Japan. Europe is waiting.