Development of the next generation radiation therapy based on molecular imaging

为了观察分次放射治疗（RT）前和放疗期间肿瘤内缺氧区域及其再氧情况，采用18f -氟米唑正电子发射断层扫描和F-MISO PET/CT扫描。10例患者包括4例头颈癌、4例胃肠癌、1例肺癌和1例子宫癌。F-MISO PET/CT在放疗前和分割放疗期间进行了两次，10名患者中有8名接受了约20 Gy/10次的分割放疗。测量正常肌肉和肿瘤的F-MISO最大标准化摄取值（SUVmax）。计算F-MISO SUVmax的肿瘤与肌肉（T/M）比。正常肌肉的平均SUVmax±标准差（SD）为1.25±0.17，SUVmax高于平均值+ 2 SD（≧1.60 SUV）为缺氧区。10个肿瘤中有9个的F-MISO SUVmax等于或大于1.60。两次检查的8个肿瘤在大约20 Gy时，SUVmax、T/M比或缺氧体积百分比（F-MISO≧1.60）均下降，表明再氧合。综上所示，在我们的F-MISO PET/CT系统中，累积≥1.60 SUV的F-MISO可视为肿瘤内缺氧区。在这个小系列中，大多数人类肿瘤（90%）在放疗前都有缺氧区域，尽管10个肿瘤中有4个的缺氧体积很小（0.0-0.3%）。此外，大多数肿瘤在分步放疗两周时出现再氧合。

To visualize intratumoral hypoxic areas and their reoxygenation before and during fractionated 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.