摘要
背景与目的:调强放射治疗(IMRT)可显著改善全乳切线野照射中靶区与邻近危及器官的剂量学分布,然而各放疗单位优化设计全乳IMRT计划的方法仍存在较大差异。本研究利用三维治疗计划系统进行全乳IMRT的多种计划设计,以探讨最优化的设计方法。方法:选择10例接受保乳手术的乳腺癌病例进行全乳放射治疗的常规、正向与逆向计划设计。用子野总数、总跳数等评价计划效率,用剂量体积直方图(DVH)比较靶区剂量和危及器官的受照射剂量差异。结果:正向IMRT计划包括人工优化法(MO)、多点强制均匀优化法(PO)和自动逆向优化法(AO)等3种,子野总数的中位数分别是5、5.5和5个,逆向IMRT的中位数为20个。总跳数分别为225.8、228.4、226.4和345.8。在正向调强计划中,靶区覆盖率和剂量分布均匀性以AO计划较好(P≤0.01),而心脏、同侧肺、肝脏、对侧肺和对侧乳腺的平均剂量(D_(mean))在AO和PO计划中明显小于MO计划(P≤0.05)。逆向IMRT计划在改善PTV剂量分布均匀性以及减少OARs照射上较正向IMRT计划更好(P≤0.05)。结论:初步建立了全乳IMRT计划设计的方法,以正向计划中AO优化法在效率和剂量学优势上最适合。逆向IMRT计划较正向计划体现了更好的剂量学优势,但需要进一步研究其成熟的设计方法。
Background and purpose： Intensity-modulated radiotherapy（IMRT） can significantly improve the dosimetric distribution of both the target and organs at risk compared to tangential irradiation for whole breast. However, its optimized methods remain different and conflicting for many radiotherapy institutions. In order to achieve the optimized planning of IMRT for the irradiation of intact breast, we investigated different optimizing methods in three dimensional radiotherapy planning system. Methods： Ten patients with early-stage breast cancer after breast conserving surgery were eligible for the study. Two kinds of plans were performed on each patient in three-dimensional treatment planning system, inverse planning IMRT and forward planning IMRT which included 3 different 6ptimizing methods as manual optimizing（MO）, multiple points optimizing（PO） and automated inverse optimizing（AO）. Various parameters were used to evaluate the efficacy of different IMRT plans. All plans were compared using dose volume histograms（DVH） for the planning target volume（PTV） and organs at risk（OARs）. Results： For MO, PO, AO forward plans and inverse plans, median number of segments were 5, 5.5, 5 and 20 respectively, and mean total MU were 225.8, 228.4, 226.4 and 345.8 MU, respectively. Comparing the different forward planning optimizations, the best target coverage and dose homogeneity of PTV was observed in AO plans（P≤0.01）, and PO and AO plans showed a better reduction of OARs exposure compared with MO plans（P≤0.05）. A further improvement of dose homogeneity in the PTV and better sparing of OARs was achieved using inverse planning（P≤0.05）. Conclusion： Forward planning IMRT with AO optimization for intact breast irradiation could provide both efficacy and dosimetric advantages better thanothers. The inverse IMRT plan showed more potential in improving the dosimetric outcomes. However, further studies are required for inverse optimizing plans.
出处
《中国癌症杂志》
CAS
CSCD
2008年第11期832-838,共7页
China Oncology
关键词
乳腺肿瘤/放射疗法
调强放射治疗
三维放射治疗计划/正向
逆向
剂量体积直方图
breast neoplasms, radiotherapy
intensity-modulated radiotherapy
three dimensional radiotherapy planning, forward, inverse
dose volume histograms
