[The present and future of heavy charged particle therapy]

Introduction of heavy charged particles (protons and heavy-ions) is a promising approach in cancer treatment, permitting selective irradiation to the tumor while minimizing irradiation to the surrounding normal tissues. Additionally, the efficiency of heavy-ions will be further augmented by an increased biological effectiveness caused by high-LET components. At the University of Tsukuba, treatment with 250 MeV proton beams is being performed and, unlike other facilities in the world, successful results have been obtained in the thoraco-abdominal and pelvic tumors. Heavy-ion therapy was initiated at the University of California, and in 1993 the first heavy-ion synchrotron complex dedicated to medical use in a hospital environment was completed at the National Institute of Radiological Sciences. The carbon-ion therapy was begun in June 1994 which is expected to provide optimal results in various type of tumors. A construction of heavy-ion facility is also under consideration in Germany (GSI), Austria (AUSTRON), Italy (TERA) and Japan (Hyogo prefecture).