Cancer therapy with particle accelerators

This review paper is devoted to conventional radiotherapy and to hadron therapy. In this therapeutical modality, proposed by R. R. Wilson in 1946, the physical selectivity of proton and light ion beams is used to irradiate tissues very close to organs at risk, which cannot be irradiated (the brain and the spinal cord for instance). Also fast neutrons are employed, but they are not suitable for a truly conformal irradiation. Carbon ions have the added advantage, with respect to protons, of the high density of ionization at the end of the range in matter. This property is very valuable for the control of tumours which are radioresistant to both X-rays and protons. After clarifying the general principles, a review is presented of the world hadron therapy centres which are running or are in the design and construction stage. (33 refs).