Water radiolysis near the Bragg peak of therapeutic heavy ions, 1; Measurement of OH yield with a fluorescent probe

Yamashita, Shinichi; Maeyama, Takuya*; Midorikawa, Masamichi*; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Kudo, Hisaaki*; Katsumura, Yosuke; Murakami, Takeshi*

Recently, cancer therapy with high-energy heavy ions has been utilized, showing high efficiency in actual treatment. While its effectiveness has already been certificated phenomenologically, detailed mechanism through which such a feature appears has not been clarified yet. Water is a main component of human body, and then, it is inevitably important to comprehend water radiolysis. In this study, water radiolysis near the Bragg peak was focused on because the peak is overlapped to cancer in actual treatment, and yield of hydroxyl radical (OH) has been determined because OH is assumed as a species most responsible to indirect action. In addition, contribution of fragmentation reactions which is significant for high-energy heavy ions were discussed from the viewpoint of OH yield.