Radiation safety planning for particle therapy facilities

In recent years a series of particle therapy facilities was built worldwide. Initially particle therapy was realized in large scale research facilities as for example in Berkeley (USA), Harvard (USA), Chiba (Japan), PSI (Switzerland) or in Germany at HMI (Berlin) and at GSI (Darmstadt). For particle therapy mainly proton beams are used. Ion beams with masses up to carbon or even heavier ions are used for particle therapy, too. Due to the increasing number of particle therapy facilities in USA, Japan, South Korea, China, Italy and Germany one can observe that this kind of tumor therapy becomes gradually established in the clinical environment. The work presented here deals with issues related to radiation protection for the planning phase of a particle therapy facility. The discussion focuses on topics like the production of radiation in the accelerator and in the treatment rooms for different kinds of beams, source distributions of produced neutron radiation, beam loss distributions in cyclotron and synchrotron facilities, the definition of radiological areas and the architectural shielding layout of the facility. Methods for the estimation of radiation levels outside the shielding and the calculation of shielding thicknesses are discussed. Finally an example for a particle therapy facility, the Heidelberg Ion Therapy Center, is presented. (orig.)