直肠癌术前五野静态调强和容积弧形调强放疗剂量学的比较研究

Dosimetric comparison between preoperative five-field intensity modulated radiotherapy and volumetric modulated arc therapy in the treatment of rectum cancer

目的探讨直肠癌术前五野静态调强(5F-IMRT)和容积弧形调强(VMAT)放疗计划的剂量学特点。方法应用CMS monaco治疗计划系统分别对23例术前同期放化疗的直肠癌患者行5F-IMRT和VMAT放疗计划设计,比较两种放疗技术的靶区剂量分布特点以及小肠、膀胱、双侧股骨头等正常组织的受照射剂量及体积。结果 5F-IMRT计划的适形指数(CI)为0.810±0.043,VMAT计划的CI为0.822±0.062,两者均能很好满足95%等剂量曲线对100%PTV体积的完全覆盖;5F-IMRT计划中GTV、CTV和PTV的均匀指数(HI)分别为1.052±0.019、1.063±0.016、1.075±0.020,VMAT计划分别为1.037±0.008、1.047±0.008、1.072±0.018,差异均无统计学意义。5F-IMRT和VMAT计划中重要的危及器官如小肠、膀胱和股骨头等的关键剂量评价指标(D5、Dmin、Dmean和Dmax)差异均无统计学意义(P>0.05)。小肠、膀胱和股骨头等受照射体积的关键评价指标(V20、V30、V40和V50)在两种放疗计划中差异均无统计学意义(P>0.05)。结论 5F-IMRT和VMAT计划靶区的剂量分布均较理想,对小肠、膀胱、双侧股骨头等正常组织均有很好的保护作用。

Objective To investigate the dosimetric comparison between preoperative five-field intensity modulated radiotherapy（5F-IMRT） and volumetric modulated arc therapy（VMAT） in the rectum cancer patients with concurrent chemotherapy and radiotherapy.Methods With the application of CMS monaco systems（V2.0,Sweden）,5F-IMRT and VMAT plans were simulated in 23 rectum cancer patients with preoperative concurrent chemoradiotherapy.The dose characteristic of target volume was evaluated and the dose-volume relationship of small bowel,bladder and bilateral femoral head was compared.Results The CI was similar between the 5F-IMRT（0.810±0.043） and VMAT plans（0.822±0.062）,which could satisfy 95% of prescribed dose for covered PTV.The HI of the prescribed dose to GTV（1.052±0.019 vs.1.037±0.008）,CTV（1.063±0.016 vs.1.047±0.008） and PTV（1.075±0.020 vs.1.072±0.018） in the two kinds of plans was similar too.There was no significant difference for the key parameters（D5,Dmin,Dmean and Dmax） of risk organs such as intestine,bladder and femoral head in the two plans（P〉0.05）.There was no significant difference for the key parameters of irradiated volume such as V20,V30,V40 and V50 of risk organs between the 5F-IMRT and VMAT plans（P〉0.05）.Conclusion VMAT plans was as good as 5F-IMRT in the prescribed dose for the target volume,and risk organs such as intestine,bladder and femoral head could be well protected.