乳腺癌根治术后调强计划的设计比较

Comparison of Modulation Radiotherapy Planning for Breast Cancer after Radical Mastectomy

目的分析加速器多叶光栅(MLC)对乳腺癌计划设计的影响,并比较不同计划中心下,乳腺癌计划质量的变化。方法随机选取7例右侧乳腺癌根治术后患者,应用Pinnacle 9.1计划系统,加速器使用医科达Axesse和Synergy两种机型。每例患者在Axesse下做移动计划中心和不移动中心的计划各1个;在Synergy下做移动中心计划1个。在保证90%处方剂量线包绕计划靶区(PTV)的前提下,分析比较3种调强PTV的适形度、均匀性及危及器官的受量。结果通过7例右侧乳腺癌患者的调强计划比较后发现,在Axesse下和Synergy下,移动中心到相同位置的调强PTV适形度分别为(0.78±0.02)和(0.68±0.02),差异有统计学意义(t=5.196,P<0.05);剂量均匀性分别为(10.39±0.56)和(12.38±0.86),差异有统计学意义(t=4.997,P<0.05)。比较在Axeese和Synergy下所做计划,患侧肺的V20从16.11%下降到14.67%。移动中心与不移动中心的计划比较,PTV的适形度和剂量均匀性有一定优化,患侧肺的V20分别为(14.67±0.28)%和(15.10±0.35)%,差异有统计学意义(P<0.05)。结论 MLC的参数对计划结果有显著影响,叶片宽带越窄,相同条件做出的计划质量越好。移动计划中心可以减少乳腺癌患者患侧肺的剂量受量。

Objective To analyse the effect of multi-leaf collimator(MLC) in treatment planning for breast cancer and the quality change of the treatment plans as we shift the planning center. Methods 7 patients of breast cancer after radical mastectomy were randomly selected. We designed one plan with plan center changed and one plan of the same patient with plan center unchanged on Axesse. Another plan with plan center changed was designed on Synergy. All these plans were finished on Pinnacle 9.1 treatment planning system. In each plan, the planning target volume(PTV) received prescription dose was more than 90%. Dosimetric parameters of PTV and organs at risk were compared. Results After comparing the intensity-modulation plans of 7 cases of right breast cancer, it was found that under Axesse and Synergy, the PTV conformity were(0.78±0.02) and(0.68±0.02) respectively(t=5.196,P<0.05), target homogeneity index were(10.39±0.56) and(12.38±0.86) respectively(t=4.997,P<0.05), and V20 of right lung decreased from 16.11% to 14.67%;the target conformity and target homogeneity index of changed center plans were better than unchanged center plans’,and V20 of right lung were(14.67±0.28)% and(15.10±0.35)% respectively(t=-4.102,P<0.05). Conclusion The MLC indexs of accelerators have sufficient effect on the results of plans. The width of leaf is smaller, the quality of plan is better. The dose received by the right lung decreases as we shift the plan center.