[目的]评价18F-FLT和18F-FDG PET显像在早期评价肺大细胞癌放疗疗效中的作用。[方法]18只荷肺大细胞癌小鼠随机分为18F-FLT和18F-FDG两组,各组又随机配对分为A组、B组、C组,每组3只。A组为对照组,未进行任何治疗;B组于实验前1d对小鼠肿瘤部位进行放疗,单次剂量X线2000cGy,能量6MV;C组于实验前2d同样对小鼠肿瘤部位进行放疗,放疗剂量同B组。经小鼠尾静脉注入18F-FLT和18F-FDG后行MicroPET显像,于注射后60min进行PET显像。[结果]放疗后肺大细胞癌18F-FLT摄取较对照组明显降低(1.33%±0.27%和0.58%±0.08%,P<0.05),FDG组FDG摄取放疗后48h与对照组比较有显著性差异(P<0.05)。PET显像FLT组在放疗后24h、48h后T/NT值明显低于对照组(P<0.05),而FDG放疗组48h与对照组相比有统计学差异(P<0.05)。[结论]18F-FLT可被肺部恶性肿瘤摄取,其特异度高于18F-FDG。放疗引起的18F-FLT摄取变化较18F-FDG灵敏,放疗后18F-FLT摄取降低较18F-FDG明显,因而18F-FLT是一种监测恶性肿瘤放疗疗效的有效的示踪剂。 [Objective] To evaluate the role of 18F-FLT and 18F-FDG PET in the early evaluation of radiotherapy for pulmonary large cell carcinoma. [Methods] Twenty-eight mice with large cell lung cancer were randomly divided into 18F-FLT group and 18F-FDG group. Each group was randomly divided into group A, group B and group C, with 3 rats in each group. Group A was the control group, without any treatment; group B before the experiment 1d on the tumor site of mice radiotherapy, a single dose of X-ray 2000cGy, energy 6MV; C group 2d before the experiment the same tumor part of the mice for radiation therapy, Radiotherapy dose with the B group. MicroPET imaging was performed by injecting 18F-FLT and 18F-FDG into the caudal vein of mice and PET imaging was performed 60min after injection. [Results] The uptake of 18F-FLT in pulmonary large cell carcinoma was significantly lower than that of the control group (1.33% ± 0.27% and 0.58% ± 0.08%, P <0.05) after radiotherapy. The FDG uptake 48h after radiotherapy was significantly higher than that of the control group Difference (P <0.05). T / NT values ​​of PET imaging FLT group after 24h and 48h after radiotherapy were significantly lower than those of control group (P <0.05), but there was significant difference between FDG radiotherapy group and control group (P <0.05). [Conclusion] 18F-FLT can be taken up by malignant tumor of the lung and its specificity is higher than that of 18F-FDG. The uptake of 18F-FLT induced by radiotherapy is more sensitive than that of 18F-FDG, and the 18F-FLT uptake after radiotherapy is significantly lower than that of 18F-FDG. Therefore, 18F-FLT is an effective tracer to monitor radiotherapy of malignant tumor.