57. Experiences of Carbon Ion Radiotherapy at NIRS

Hirohiko Tsujii, Shinroku Morita, Tadaaki Miyamoto, Jun-etsu Mizoe, Tadashi Kamada, Hirotoshi Kato, Hiroshi Tsuji, Shigeru Yamada, Naotaka Yamamoto and Hajime Murata

Keywords: carbon ion radiotherapy, HIMAC, heavy ion

Functional and cosmetic preservation is of paramount importance in cancer therapy. For this purpose, heavy ion therapy is an advantageous modality over megavoltage x-ray therapy in terms of safely delivering high doses coupled with increased cell-killing ability. Heavy ions have the beneficial property of superior physical dose localization due to exhibiting the Bragg peak in the body, as well as greater biological effectiveness than low-LET radiation (protons and photons). Thus, heavy ions are expected to be effective against locally advanced radio-resistant tumors and those located near critical structures. In 1993, construction and installation of the Heavy Ion Medical Accelerator in Chiba (HIMAC), the world's first heavy ion accelerator complex dedicated to medical use in a hospital environment, was completed at NIRS. The HIMAC project was initiated as part of the Japanese government's 10-year plan to combat cancer. In June 1994, clinical research for the treatment of malignant tumors was begun using carbon ions generated by the HIMAC. Since then more than 1,000 patients have been treated with carbon ions, in which both the phase I/II dose escalation study and phase II study were performed.

Tables 2-5 summarize the results of carbon ion radiotherapy including the radiation-induced morbidity, local control, and survival rates for patients with various types of tumors.