中华放射医学与防护杂志

铁剑,孙艳,弓健,韩树奎,蒋璠,吴昊.保乳术后固定野动态调强与容积调强放疗的剂量学比较[J].中华放射医学与防护杂志,2011,31(3):317-321

保乳术后固定野动态调强与容积调强放疗的剂量学比较

Dosimetric study comparing volumetric arc modulation with RapidArc and fixed field dynamic intensity-modulated radiation therapy for breast cancer radiotherapy after breast-conserving surgery

投稿时间：2010-09-15

DOI：10.3760/cma.j.issn.0254-5098.2011.03.017

中文关键词: 乳腺癌保乳手术调强放疗容积调强放疗剂量学比较

英文关键词:Breast cancer Breast-conserving surgery Intensity modulated radiation therapy Volumetric modulated arc therapy Dosimetry

基金项目:

作者	单位
铁剑	100142 北京大学临床肿瘤学院北京肿瘤医院暨北京市肿瘤防治研究所放疗科恶性肿瘤发病机制及转化研究教育部重点实验室
孙艳	100142 北京大学临床肿瘤学院北京肿瘤医院暨北京市肿瘤防治研究所放疗科恶性肿瘤发病机制及转化研究教育部重点实验室
弓健	100142 北京大学临床肿瘤学院北京肿瘤医院暨北京市肿瘤防治研究所放疗科恶性肿瘤发病机制及转化研究教育部重点实验室
韩树奎	100142 北京大学临床肿瘤学院北京肿瘤医院暨北京市肿瘤防治研究所放疗科恶性肿瘤发病机制及转化研究教育部重点实验室
蒋璠	100142 北京大学临床肿瘤学院北京肿瘤医院暨北京市肿瘤防治研究所放疗科恶性肿瘤发病机制及转化研究教育部重点实验室
吴昊	100142 北京大学临床肿瘤学院北京肿瘤医院暨北京市肿瘤防治研究所放疗科恶性肿瘤发病机制及转化研究教育部重点实验室

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中文摘要:

目的比较早期乳腺癌保乳术后固定野动态调强与容积调强放疗治疗靶区和危及器官的剂量学差异。方法 20例左侧乳腺癌患者(均女性,24~75岁)保乳术后接受放疗,在同一患者CT影像上分别进行2野共面动态调强和容积调强(RapidArc)两种治疗计划设计。在剂量-体积直方图中读取两种计划的靶区剂量分布参数,心脏、双侧肺及对侧乳腺受照剂量和体积,对各参数的均数进行比较;并比较两者平均机器跳数和平均治疗时间的差异。结果 RapidArc较IMRT计划CTV V_95%增加了0.65%(t=5.16, P =0.001),V_105%下降了10.96%(t=-2.05, P =0.055),V_110%下降了1.48 %(t=-1.33, P =0.197)。RapidArc计划的适形指数(CI)和均匀性指数(HI)均优于IMRT治疗计划,分别为0.88±0.02 vs 0.74±0.03(t=18.54, P ﹤0.001),1.11±0.01 vs 1.12±0.02(t=-2.44, P =0.025)。两种计划中左肺V₂₀和 D_max比较差异无统计学意义,但在RapidArc计划中V₁₀、V₅、 D_min、 D_mean明显增高,V₅增高了接近30%。心脏V₃₀和 D_max在两计划中无明显差异,而RapidArc计划的V₁₀增加了18%,V₅增加50%。RapidArc计划的右乳V₅和右肺V₅较IMRT分别增加了9.33%(t=9.31, P ﹤0.001)和3.04%(t=5.64, P ﹤0.001)。RapidArc和IMRT平均机器跳数分别是608 和437 MU(t=10.86, P ﹤0.001),平均治疗时间111.3和103.6 s(t=3.57, P =0.002)。结论早期乳腺癌保乳术后全乳腺RapidArc放疗与2野动态调强放疗相比,能明显改善靶区剂量分布均匀性。对于危及器官,高剂量区两种治疗计划之间无明显差异,低剂量区RapidArc的照射范围明显增加。与2野动态调强相比,RapidArc放疗机器跳数增加,治疗时间延长。

英文摘要:

Objective To compare the dosimetric difference between volumetric arc modulation with RapidArc and fixed field dynamic IMRT for breast cancer radiotherapy after breast-conserving surgery. Methods Twenty patients with early left-sided breast cancer received radiotherapy after breast-conserving surgery. After target definition, treatment planning was performed by RapidArc and two fixed fields dynamic IMRT respectively on the same CT scan. The target dose distribution, homogeneity of the breast, and the irradiation dose and volume for the lungs, heart, and contralateral breast were read in the dose-volume histogram (DVH) and compared between RapidArc and IMRT. The treatment delivery time and monitor units were also compared. Results In comparison with the IMRT planning, the homogeneity of clinical target volume (CTV), the volume proportion of 95% prescribed dose (V_95%) was significantly higher by 0.65% in RapidArc (t=5.16, P =0.001),and the V_105% and V_110% were lower by 10.96% and 1.48 % respectively, however, without statistical significance (t=-2.05, P =0.055 and t=-1.33, P =0.197).The conformal index of planning target volume (PTV) by the RapidArc planning was (0.88±0.02), significantly higher than that by the IMRT planning [(0.74±0.03),t=18.54, P ﹤0.001]. The homogeneity index (HI) of PTV by the RapidArc planning was 1.11±0.01, significantly lower than that by the IMRT planning (1.12±0.02,t=-2.44, P =0.02). There were no significant differences in the maximum dose ( D_max) and V₂₀ for the ipsilateral lung between the RapidArc and IMRT planning, but the values of V₁₀, V₅, D_min and D_mean by RapidArc planning were all significantly higher than those by the IMRT planning (all P <0.01). The values of max dose and V₃₀ for the heart were similar by both techniques, but the values of V₁₀ and V₅ by the RapidArc planning were significantly higher (by 18% and 50%, respectively). The V₅ of the contralateral breast and lung by the RapidArc planning were increased by 9.33% and 3.04% respectively compared to the IMRT planning. The mean MU of the RapidArc was 608 MU, significantly higher than that by the IMRT planning (437 MU,t=10.86, P ﹤0.001). The treatment time by the RapidArc planning was 111.3 s, significantly longer than that by IMRT planning (103.6 s,t=3.57, P =0.002).Conclusions The RapidArc planning improves the dose distribution of CTV and homogeneity of PTV for breast cancer radiotherapy after breast-conserving surgery. However, it significantly enlarges the volume of normal tissues irradiated in low dose areas, prolongs the treatment delivery time, and increases the MU value in comparison with IMRT.

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