@misc{oai:repo.qst.go.jp:00069300,
 author = {Matsumoto, Kenichiro and Matsumoto, Atsuko and Nyuui, Minako and Ueno, Megumi and Manda, Sushma and Anzai, Kazunori and 松本 謙一郎 and 松本 厚子 and 乳井 美奈子 and 上野 恵美 and Ｍａｎｄａ Ｓｕｓｈｍａ and 安西 和紀},
 month = {Mar},
 note = {Introduction: High LET carbon ion beam cancer therapy at National Institute of Radiological Sciences (Chiba, Japan) began in 1994. Considering the expansion of heavy-ion cancer therapy, the quality and accuracy of the heavy-ion therapy must be improved and optimized. Detection of free radical reactions and geometry in a large sample irradiated by a heavy-ion beam is thus important to understand the effect of high LET irradiation in patients. Therefore, a new method to detect free radical generation, which can be translated to an imaging technique, is required. In this experiment, using an X-ray irradiation, the imaging-translational detection of H2O2 generation in an aqueous sample was tested. Method: LiPc crystal was put into a plastic microtube. The microtube was filled with mili-Q water or PBS, and sealed air-tightly without any bubble in the tube. The tube was irradiated by X-ray (Eeff = 80 keV) with dose of 256 Gy. After the irradiation, EPR spectra of LiPc in the tube were measured at L-band (1.2 GHz). The pO2 value in the tube was estimated from the linewidth of EPR spectrum of LiPc. A similar sample without LiPc was irradiated by X-ray (256 Gy), and then H2O2 concentration in the tube was measured. A water solution of TEMPOL (2 mM) was irradiated by X-ray (356 Gy), and the reduction of the EPR signal of TEMPOL was measured. Results and Discussion: By irradiating 256 Gy of X-ray, pO2 in the irradiated water was decreased by 30 mmHg, and generation of 60 mol/L H2O2 in the irradiated water was detected. When a water solution of TEMPOL (2 mM) was irradiated by 256 Gy of X-ray, EPR signal of TEMPOL in the sample was decreased. The H2O2 generated in the water during the irradiation can make the reduction of TEMPOL without hydrogen-donor, such as GSH, NADH, or NADPH. This experimental design will be translated to imaging experiment and applied to the high LET radiation such as heavy-ion beams in the future., Oxygen Club of California 2008 World Congress},
 title = {Free radical reaction and oxygen consumption in an aqueous solution by an X-ray irradiation},
 year = {2008}
}