Development of a New Radiotherapy Evaluation Method With Positron Emission Tomography

发现L- [甲基-C-11]甲硫氨酸（C-11-Met）的肿瘤摄取对放疗的反应比肿瘤体积缩小和坏死扩展更敏感（JNM 30 ; 2012-16）。为了寻找肿瘤放射治疗监测的最佳示踪剂，肿瘤研究的代谢示踪剂代表葡萄糖、氨基酸和核酸代谢; 2-脱氧-2- [F-18]氟-D-葡萄糖（F-18-FDG），L- [甲基-C-14]蛋氨酸（C-14-Met）、[6-H-3]胸苷（H-3-Thd）和2 '-脱氧-5- [F-18]氟尿苷（F-18-FdUrd）和传统的[Ga-67]柠檬酸盐（Ga-67）进行了比较，使用相同的rattumor模型AH 109 A与四重示踪剂技术。采用两种四重示踪剂组合（F-18-FDG或F-18-FdUrd，C-14-Met，H-3-Thd和Ga-67）对5种示踪剂进行了20戈伊单次照射后的时程研究和5、10、15和20戈伊照射后6天的剂量依赖性研究。使用能谱和半衰期的差异对每种放射性核素进行测量。F-18-FDG具有摄取变化范围广、放疗反应稳定等优点。F-18-FdUrd下降迅速，但范围较窄。Ga-67在治疗后不能立即观察到肿瘤反应，但随后显示出广泛的摄取变化。H-3-Thd和C-14-Met显示快速响应和高灵敏度用于监测放射治疗，表明C-11-Thd和C-11-Met似乎是正电子发射断层扫描研究的理想选择。

Tumor uptake of L- [methyl-C-11] methionine (C-11-Met) was found to respond to radiotherapy more sensitively than does the tumor volume reduction and the extension of necrosis (JNM 30 ; 2012-16). In order to find the best tracer for monitoring tumor radiotherapy, metabolic tracers for tumor study representing glucose, amino acid and nucleic acid metabolisms ; 2-deoxy-2- [F-18] fluoro-D-glucose (F-18-FDG), L- [methyl-C-14] methionine (C-14-Met), [6-H-3] thymidine (H-3-Thd), and 2'-deoxy-5- [F-18] fluorouridine (F-18-FdUrd) ; and conventional [Ga-67] citrate (Ga-67) were compared using a same rattumor model AH109A with quadruple-tracer technique. Two combinations of quadruple-tracers each (F-18-FDG or F-18-FdUrd, C-14-Met, H-3-Thd and Ga-67) were used for comparison of 5 tracers in the time-course study frter 20 Gy single-dose irradiation and in the dose-dependency study 6 days arfer 5, 10, 15 and 20 Gy irradiation. Measurements of each radionuclide were performed using the differences of energy spectrum and half-life. F-18-FDG has advantage of its wide range of uptake change and steady response to radiotherapy. F-18-FdUrd showed rapid decrease but the range was narrow. Ga-67 cannot etect the tumor response esrly after treatment, but showed wide range of uptake change later. H-3-Thd and C-14-Met showed rapid responses and high sensitivity for monitoring the radiotherapy suggesting that C-11-Thd and C-11-Met seem to be ideal for the positron emission tomography study.