Development of a New Radiotherapy Evaluation Method With Positron Emission Tomography

肿瘤摄取L-[甲基- c -11]蛋氨酸（C-11-Met）对放疗的反应比肿瘤体积缩小和坏死扩大更敏感（JNM 30; 2012-16）。为了寻找监测肿瘤放疗的最佳示踪剂，研究肿瘤代谢示踪剂代表葡萄糖、氨基酸和核酸的代谢；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]胸腺嘧啶（H-3-Thd）和2'-脱氧-5- [F-18]氟吡啶（F-18- fdurd）；与常规[Ga-67]柠檬酸盐（Ga-67）采用四联示踪技术对同一肿瘤模型AH109A进行比较。在20 Gy单剂量照射后的时间过程研究和5、10、15和20 Gy照射后6天的剂量依赖性研究中，采用两种四联示踪剂组合（F-18-FDG或F-18-FdUrd、C-14-Met、H-3-Thd和Ga-67）对5种示踪剂进行比较。利用能谱和半衰期的差异对每种放射性核素进行了测量。f18 - fdg具有吸收变化范围广、对放疗反应稳定的优点。F-18-FdUrd下降速度快，但幅度小。Ga-67在治疗后不能立即影响肿瘤反应，但在治疗后表现出大范围的摄取变化。H-3-Thd和C-14-Met对放射治疗的监测反应快，灵敏度高，表明C-11-Thd和C-11-Met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.