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目的:比较基于两种类型多叶准直器(Multileaf Collimator,MLC)的胸膜间皮瘤容积旋转调强放疗(Volumetric Modulated Arc Therapy,VMAT)计划差异。材料与方法:回顾性选取10例因各种无法手术的胸膜间皮瘤患者CT图像,分别采用配置常规多叶准直器(Standar MLC,s MLC)和微型多叶准直器(micro-MLC,m MLC)的医科达直线加速器进行VMAT的计划设计。比较两种计划在靶区(Planning Target Volume,PTV)适形度(Conformity Index,CI)、均匀度(Heterogeneity Index,HI)以及危及器官(Organs At Risk,OAR)剂量体积参数方面的异同。结果:与基于s MLC的VMAT计划(s MLC-VMAT)相比,基于m MLC的VMAT计划(m MLC-VMAT)实施效率高(平均实施时间:2.57±1.66 min vs 3.27±1.65 min,P<0.05)。此外,m MLC-VMAT计划靶区适形度和均匀度优于s MLC-VMAT(CI:0.75±0.08 vs 0.71±0.12;HI:1.09±0.02 vs 1.11±0.03)。就OARs而言,除心脏的Dmean(P=0.042)以外,其它各个OARs的剂量体积参数差异均无显著性意义(P>0.05)。结论:与s MLC-VMAT计划相比,m MLC-VMAT计划不仅明显缩短了治疗时间,提高靶区的覆盖度与均匀性,而且显著降低了心脏的平均受照剂量,有助于减小心血管病的发生风险。
OBJECTIVE: To compare the differences between the plans of Volumetric Modulated Arc Therapy (VMAT) based on two types of Multileaf Collimator (MLC). MATERIALS AND METHODS: Ten CT images of patients with pleural mesothelioma who were unable to operate were retrospectively selected. They were treated with Standar MLC (s MLC) and micro-MLC , m MLC) of the medical science linear accelerator VMAT plan design. The similarities and differences between the two plans in the Planning Target Volume (PTV) Conformity Index (CI), Heterogeneity Index (HI) and Organs At Risk (OAR) dose volume parameters were compared. RESULTS: The m MLC-based VMAT plan (m MLC-VMAT) was highly efficient (mean implementation time: 2.57 ± 1.66 min vs. 3.27 ± 1.65 min vs P <0.05) compared to the s MLC-based VMAT plan 0.05). In addition, the conformability and uniformity of the m MLC-VMAT target were superior to s MLC-VMAT (CI: 0.75 ± 0.08 vs 0.71 ± 0.12; HI: 1.09 ± 0.02 vs 1.11 ± 0.03). In terms of OARs, there were no significant differences in dose-volume parameters for all OARs except Dmean (P = 0.042) in the heart (P> 0.05). CONCLUSIONS: Compared with the s MLC-VMAT program, the m-MLC-VMAT program not only significantly shortened the treatment time, increased the coverage and uniformity of the target area, but also significantly reduced the mean dose of the heart and decreased the heart Risk of vascular disease.