A proton therapy system in Nagoya Proton Therapy Center.

The purpose of this paper is to describe an outline of a proton therapy system in Nagoya Proton Therapy Center (NPTC). The NPTC has a synchrotron with a linac injector and three treatment rooms: two rooms are equipped with a gantry and the other one is equipped with a fixed horizontal beamline. One gantry treatment room has a pencil beam scanning treatment delivery nozzle. The other two treatment rooms have a passive scattering treatment delivery nozzle. In the scanning treatment delivery nozzle, an energy absorber and an aperture system to treat head and neck cancer have been equipped. In the passive treatment delivery nozzle, a multi-leaf collimator is equipped. We employ respiratory gating to treat lung and liver cancers for passive irradiation. The proton therapy system passed all acceptance tests. The first patient was treated on February 25, 2013, using passive scattering fixed beams. Respiratory gating is commonly used to treat lung and liver cancers in the passive scattering system. The MLCs are our first choice to limit the irradiation field. The use of the aperture for scanning irradiation reduced the lateral fall off by half or less. The energy absorber and aperture system in scanning delivery is beneficial to treat head and neck cancer.