Recent developments on particle therapy at NIRS Japan

NIRS proposed a new carbon-ion radiotherapy facility in order to boost applications of carbon-ion radiotherapy in Japan, with emphasis being placed on a downsized version so as to reduce cost. The proposed facility was designed, based on the experience in the HIMAC treatments. The key technologies regarding the accelerator and beam delivery systems to be downsized for the new facility were developed during two years from April 2004 to March 2006, and their performances were verified by beam tests with HlMAC. The fruits of this work were realized in the Gunma University Heavy-Ion Medical Center, which has been conducted since 2010. NIRS, further, has been engaged in a new treatment research project since April 2006 for the further development of HIMAC treatments. One of most important purposes in this project is to realize an 'adaptive cancer radiotherapy', which can accurately treat tumors even with changing size and shape during a treatment period. Since NIRS treats both fixed and moving tumors, it has proposed a fast 3D rescanning method with the gated irradiation to move toward the goal of adaptive cancer radiotherapy for treating both the moving and fixed tumors. Essential technologies in this method is 100 times faster 3D scanning compared with the conventional ones. As a result of experiments using the test bench installed in the HIMAC facility, we verified the desired physical dose distribution was successfully obtained for both the fixed and moving targets and the expected result of HSG-cell survival was also obtained. On the basis of this technology, the new treatment research facility at HlMAC was constructed