Online ISSN: 1884-4111 Print ISSN: 0033-8303
Radioisotopes 68(10): 709-714 (2019)

特集Special Issues

8.2.4 高LET領域における酸素効果8.2.4 Oxygen Effect in the High LET Region

1東海大学工学部原子力工学科Department of Nuclear Engineering, School of Engineering, Tokai University ◇ 259–1292 神奈川県平塚市北金目4–1–1 ◇ 4–1–1 Kitakaname, Hiratsuka, Kanagawa 259–1292, Japan

2量子科学技術研究開発機構放射線医学総合研究所重粒子線治療研究部放射線がん生物学研究グループRadiation and Cancer Biology Group, Department of Charged Particle Therapy Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology ◇ 263–8555 千葉県千葉市稲毛区穴川4–9–1 ◇ 4–9–1 Anagawa, Inage-ku, Chiba, Chiba 263–8555, Japan

発行日:2019年10月15日Published: October 15, 2019


High LET radiation is highly expected to control hypoxic fraction in tumor tissue that shows radiation resistance to low LET radiation, because oxygen effect decreases with increasing LET. Due to the availability of various ions and LETs, HIMAC has produced many outcomes from basic to clinical studies. In the basic studies, the mechanism of decreasing oxygen effect with increasing LET was experimentally examined based on the previously proposed “oxygen in the track” model. In addition, in vitro cellular and in vivo transplanted tumor studies demonstrated the LET dependent feature of DNA damage produced under hypoxic condition. For the effort to connect basic studies to clinical trials, measurement of LET dependence of OER (Oxygen Enhancement Ratio) was extended to various oxygen concentrations to mimic oxygen environment in tumors. Finally clinical research using carbon ions for cervical cancer patients demonstrated the effective control of hypoxic fraction.

Key words: HIMAC (Heavy Ion Medical Accelerator in Chiba); oxygen enhancement ratio; LET dependence; model of small oxygen effect; hypoxic; DNA damage

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