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目的:探讨直肠癌术前三维适形放疗(3D-CRT)和五野调强放射治疗(5F-IMRT)计划的剂量学特点,及其术前放疗较佳的放疗技术。方法:对27例拟行术前放疗的直肠癌患者进行3D-CRT和IMRT 2套治疗计划设计,比较2种放疗计划的靶区剂量学特点以及小肠、膀胱和双侧股骨头等正常组织的受照射剂量及体积。结果:5F-IMRT计划中适形指数(CI)为(0.805±0.050),大于3D-CRT(0.698±0.060),P<0.001;2种计划的GTV均匀指数(HI)值均非常接近1,差异无统计学意义;5F-IMRT计划中HICTV和HIPTV值均分别小于3D-CRT计划,P<0.05。5F-IMRT计划中小肠D5、Dmin和Dmax与3D-CRT相应参数差异无统计学意义,但Dmean低于3D-CRT,P<0.05;5F-IMRT计划中小肠V30高于3D-CRT,而V50则前者低于后者,差距也有统计学意义,P=0.041。类似的结果也见于膀胱。5F-IMRT计划中左、右股骨头Dmin和Dmax均低于3D-CRT,V40也明显小于3D-CRT,P<0.05。结论:直肠癌术前放疗5F-IMRT计划剂量分布适形性及均匀性明显优于3D-CRT,且能更好地保护直肠周边邻近的正常组织器官。
Objective: To investigate the dosimetric features of preoperative 3D-CRT and 5F-IMRT and its preoperative radiotherapy for radiotherapy. Methods: 27 cases of rectal cancer patients scheduled for preoperative radiotherapy were treated with 2 sets of 3D-CRT and IMRT plans. The target dosimetric characteristics of 2 radiotherapy plans and the normal tissues of small intestine, bladder and bilateral femoral head were compared Irradiated dose and volume. Results: The conformal index (CI) of 5F-IMRT was (0.805 ± 0.050), which was higher than that of 3D-CRT (0.698 ± 0.060), P <0.001. There was no significant difference between the 5F-IMRT plans and the HIPTV plans. The values of D5, Dmin, Dmax and 3D-CRT in the P <0.05.5F-IMRT plan had no statistical significance, However, Dmean was lower than that of 3D-CRT, P <0.05. V30 of 5F-IMRT was higher than that of 3D-CRT, while V50 was lower than the latter. The difference was statistically significant (P = 0.041). Similar results are found in the bladder. In the 5F-IMRT plan, Dmin and Dmax of left and right femoral heads were both lower than those of 3D-CRT, and V40 was also significantly smaller than that of 3D-CRT, P <0.05. CONCLUSIONS: The conformability and uniformity of 5F-IMRT dose distribution in preoperative radiotherapy for rectal cancer is significantly better than that of 3D-CRT and can better protect the normal tissues and organs adjacent to the rectum.