RADIATION ONCOLOGICAL FACILITIES OF THE HIMAC

The project to construct a Heavy Ion Medical Accelerator in Chiba (HIMAC) started at NIRS in 1984, and the final design studies, including the buildings, have alreadyb een completed based upon radiation oncological requirements. HIMAC comprises two ion sources, an RFQ linac, an Alvarez linac, a synchrotron, a high-energy beam transport system, and radiation oncological facilities. The main accelerator synchrotron consists of double rings operated at a repetition rate of 0.5 Hz, with a phase difference of one half period. The required ion species lie between helium and argon in order of atomic number. The output energy varies from 100 to 800 MeV/u for ions with a charge-to-mass ratio of 1/2. Radiation oncological facilities include all of the treatment and paramedical facilities as well as experimental facilities for radiation oncology physics and biology. The sophisticated treatment facilities consist of a beam delivery system, a patient positioning system, and a treatment planning system. These systems comprise all of the devices necessary for three-dimensionally conformed irradiation which is required for heavy-ion treatment. The entire HIMAC facility will be completed in 1993.