Development of the next generation radiation therapy based on molecular imaging

研究代表者研究分担者研究分担者連携研究者publisher機関番号:34419; 研究種目：基盤研究（C）; 研究期間：2010～2012; 課題番号：22591392; 研究分野：医歯薬学; 科研費の分科・細目：内科系臨床医学・放射線科学; 細野, 眞研究成果の概要（和文）： 放射線抵抗性の低酸素領域に集積する18F-ミソニダゾール(F-MISO)を用いた臨床研究を実施した。根治照射あるいは術前照射を行った10例を対象とした。正常筋肉におけるF-MISOSUVmax は、1.26 ± 0.17 であった。これをもとに1.60 SUV（平均 + 2SD）以上のF-MISO腫瘍内集積を有意な低酸素領域とした。その結果、10例中9例では初回検査の腫瘍内F-MISOSUVmax が1.60 SUV 以上で低酸素領域を認めた。また分割照射中に2 回目の撮影の行えた8例すべてで、再酸素化現象が確認された。 研究成果の概要（英文）： ractionated radiation therapy (RT), 18F-fluoromisonidazole positron emission tomography and computed tomography (F-MISO PET/CT) were performed. Ten patients, consisting of four head and neck cancers, four gastrointestinal cancers, one lung cancer, and one uterine cancer, were included. F-MISO PET/CT was performed twice before RT and during fractionated RT of approximately 20 Gy/10 fractions for eight of the 10 patients. F-MISO maximum standardized uptake values (SUVmax) of normal muscles and tumors were measured. The tumor-to-muscle (T/M) ratios of F-MISO SUVmax were also calculated. Mean SUVmax ± standard deviation (SD) of normal muscles was 1.25 ± 0.17, and SUVmax above the mean + 2 SD (≧1.60 SUV) was regarded as a hypoxic area. Nine of the 10 tumors had an F-MISO SUVmax of equal to or more than 1.60. All eight tumors examined twice showed a decrease in SUVmax, T/M ratio, or percentage of hypoxic volume (F-MISO ≧1.60) at approximately 20 Gy, indicating reoxygenation. In conclusion, accumulation of F-MISO of ≧1.60 SUV was regarded as an intratumoral hypoxic area in our F-MISO PET/CT system. Most human tumors (90％) in this small series had hypoxic areas before RT, although hypoxic volume was minimal (0.0-0.3％) for four of the 10 tumors. In addition, reoxygenation was observed in most tumors at two weeks of the fractionated RT