直肠癌术前三维适形放疗和五野调强放疗的剂量学比较研究

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.

Dosimetric study of 3D conformal radiotherapy compared with 5F intensity modulated radiotherapy in preoperative rectum cancer

OBJECTIVE:To investigate the better mode of radiotherapy through comparing the dosimetry of 3-dimensional conformal radiotherapy(3D-CRT) and 5-field intensity modulated radiotherapy(5F-IMRT) in the patients of rectum cancer with pre-operative radiation.METHODS:3D-CRT and 5F-IMRT plan were designed to 27 rectum cancer patients with pre-operative radiotherapy,respectively.The conformity index(CI) and homogeneity index(HI)in target volume,and the dose and volume radiated of the organs at risk(OAR),such as small bowel,bladder and bilateral femoral were compared in the two kinds of plans.RESULTS:The average CI in the 5F-IMRT plan(0.805±0.050) was more than that in 3D-CRT plan(0.698±0.060,P<0.001).The HIGTV in the two kinds plans was almost close to 1 and the difference was no statistical significance.But HICTV and HIPTV in 5F-IMRT were less than that in 3D-CRT plan,and the difference was significant(P<0.05).The difference of D5,Dmin and Dmax of small bowel in the two plans was not significant,but the Dmean of small bowel in 5F-IMRT plan was less than 3D-CRT and the difference was significant(P<0.05).The V30 of small bowel in 5F-IMRT plan was larger than that in 3D-CRT,but the V50 of small bowel in 5F-IMRT was less(P=0.041).The similar results were showed in the OAR bladder.The Dmin and Dmax of bilateral femoral were less in 5F-IMRT plans than that in 3D-CRT,as well as V40(P<0.05).CONCLUSION:IMRT is superior than 3D-CRT in the conformity and homogeneity of dose distributing to the targets CTV and PTV,and in protecting of OARs from radiation in the rectum cancer patients with pre-operative radiotherapy.