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目的:比较螺旋断层调强放疗(Helical Tomotherapy,HT)和容积旋转调强放疗(Volumetric Modulated Arc Therapy,VMAT)在恶性胸膜间皮瘤放疗中的治疗计划差异。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HT和医科达Synergy VMAT直线加速器进行旋转调强放疗的计划设计。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:HT计划靶区CI和HI均显著优于VMAT计划(HI:1.04±0.01 vs 1.11±0.03;CI:0.80±0.07 vs 0.71±0.12)(P=0.000,P=0.013)。就OARs而言,HT在患侧肺V5、V10、V20、V30,健侧肺V3、V5、V10、V20,心脏V5、Dmean,脊髓Dmax均低于VMAT,其中患侧肺V30、健侧肺V5、V10、V20的差异有显著性意义(P=0.031,P=0.030,P=0.021,P=0.003)。而VMAT计划的实施效率则远高于HT计划(平均实施时间:3.27±1.65 min vs 11.11±3.75 min)(P=0.000)。结论:与VMAT计划相比,HT提高了靶区的覆盖度与均匀性,而且降低了患侧肺、健侧肺、心脏的剂量体积参数,有助于减小放射性损伤的发生风险。但HT计划的治疗实施时间较VMAT计划明显延长。
OBJECTIVE: To compare the treatment planning of Helical Tomotherapy (HT) and Volumetric Modulated Arc Therapy (VMAT) in radiotherapy of malignant pleural mesothelioma. Methods: The CT images of 10 patients with pleural mesothelioma who were unable to operate were retrospectively selected. The planning of rotation IMRT was performed by using HT and Synergy VMAT linear accelerator respectively. 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: Both CI and HI of HT target were significantly better than those of VMAT (HI: 1.04 ± 0.01 vs 1.11 ± 0.03; CI: 0.80 ± 0.07 vs 0.71 ± 0.12) (P = 0.000, P = 0.013). In terms of OARs, HT was lower than VMAT in V5, V10, V20, V30, V 3, V5, V10, V20, V5, Dmean and spinal cord in HTV, The difference of V5, V10 and V20 was significant (P = 0.031, P = 0.030, P = 0.021, P = 0.003). The implementation efficiency of the VMAT plan was much higher than that of the HT plan (mean implementation time: 3.27 ± 1.65 min vs 11.11 ± 3.75 min) (P = 0.000). CONCLUSION: Compared with the VMAT plan, HT improves the coverage and uniformity of the target area, and decreases the volume and volume parameters of affected lungs, contralateral lungs and heart, which helps to reduce the risk of radiation injury. However, HT planned treatment was significantly delayed over the VMAT program.