子野权重优化对CMS XiO宫颈癌调强计划的影响

摘要

Objective: The aim of this study is to compare the result of IMRT optimization in the CMS XiO radiotherapy treatment planning system, with and without segment weight optimization. Methods: Ten cervical cancer patients were selected for this study. All patients were initially planned with step-and-shoot IMRT (S-IMRT). A new plan was then created for each patient by applying the segment weight optimization tool (SWO-IMRT). Analysis was performed on the (SWO-IMRT) and (S-IMRT) plans by comparing the total number of segments, monitor units, rectal, bladder and small intestine dose. Results;The study showed a significant reduction in the total number of segments about26%～31% (p<0.0001) with SWO-IMRT as compared to S-IMRT. Similarly, a reduction of5.1%～9.7% (p＜0.00l) in the total MU was observed with SWO-IMRT. The method also reduced the dose of rectal, bladder and small intestine. Conclusions: This study shows that for IMRT plan of the cervical cancer, XiO' s segment weight optimization method can reduce the total number of monitor units, segments and the normal tissue' s dose. SWO-IMRT also accelerates treatment delivery. This can reduce normal tissue's toxicity and provide an opportunity for dose escalation of GTV. For other kinds of IMRT cases, SWO-IMRT can also play important roles.%目的:本文分析了CMS治疗计划系统XiO在制定调强放射治疗(IMRT)计划时,子野权重优化对治疗计划结果的影响.方法:本文选取10例宫颈癌全程放射治疗病例,制定影像引导下(IGRT)的调强放射治疗计划,首先直接用静态调强(Step&Shoot)方式进行优化一步生成调强放射治疗计划(S-IMRT),之后继续进行子野权重优化(Segment weight optimization,SWO)并生成新的治疗计划(SWO-IMRT),比较子野权重优化前后总子野数、总跳数,同时分析比较正常组织受照剂量的变化.结果:结果显示,经过子野权重优化后,总的子野数显著减少,减少约26％～31％(P＜0.0001);总的机器跳数有所降低,减少约5.1％～9.7％(P＜0.0001),同时,直肠、膀胱和小肠的剂量也有所降低.结论:在使用CMS治疗计划系统XiO进行宫颈癌全程调强放射治疗计划设计过程中,充分利用子野权重优化方式,可以减少总的机器跳数,降低正常组织剂量,缩短治疗时间,这既降低正常组织的毒性反应,也为肿瘤剂量的提高提供了可能.在其他病种的调强放射治疗计划设计中,子野权重优化也可以发挥重要的作用.