两套商用治疗计划系统中VMAT计划质量及其验证的对比研究

Comparison on plan quality and dose verification of volumetric modulated arc therapy plans designed by two commercial planning systems

目的:探讨两套商用治疗计划系统(TPS)用于喉癌与直肠癌患者容积旋转调强放疗(VMAT)的剂量学特性与验证结果差异,为其临床应用提供一定的依据。方法:选取喉癌患者10例、直肠癌患者12例,分别利用Eclipse和Pinnacle商用TPS进行VMAT及其验证计划设计,利用ArcCheck实施剂量数据的采集,分析标准为3%/3 mm和2%/2 mm条件下Gamma通过率。从计划质量、实施效率、验证结果等方面评价两套系统执行VMAT技术的差异性。结果:计划质量方面:喉癌VMAT计划中,Eclipse在危及器官保护以及计划靶区(PTV)的适形度指数(CI)、均匀性指数(HI)上与Pinnacle相近(P>0.05),Eclipse的MU要少于Pinnacle,但无统计学差异(P>0.05);直肠癌VMAT计划中,Eclipse在MU、PTV的CI和HI以及对膀胱、小肠的保护上与Pinnacle相近,在左右股骨头的V40上,Eclipse略优于Pinnacle,但无统计学差异(P>0.05)。剂量验证方面:无论是喉癌还是直肠癌VMAT计划,在分析评价标准3%/3 mm和2%/2 mm条件下,Eclipse的Gamma通过率均高于Pinnacle,且均具有统计学差异(P<0.05)。结论:尽管两套TPS的喉癌和直肠癌VMAT计划质量相近,且剂量验证均能满足临床治疗的要求,但两套计划系统在MU以及剂量验证通过率上存在一定的差异性,仍需选择更多的病例进一步探讨以确定其差异的原因。

Objective To investigate the differences in dosimetric characteristics and dose verification of volumetric modulated arc therapy(VMAT)plans designed by two commercial planning systems for patients with laryngeal and rectal cancers for providing some guidance for the clinical application of treatment planning system.Methods VMAT plans and verification plans based on Eclipse and Pinnacle were designed for 10 patients with laryngeal cancer and 12 patients with rectal cancer.ArcCheck system was used for data collection and Gamma passing rates were analyzed with the criteria of 3%/3 mm and 2%/2 mm.The plan quality,delivery efficiency and dose verification were analyzed to discuss the differences between VMAT plans based on two different planning systems.Results For patients with laryngeal cancer,the protection of organs-at-risk,the conformity index and homogeneity index of planning target area in VMAT plans based on Eclipse were similar to those in VMAT plans based on Pinnacle(P>0.05),but the monitor unit of VMAT plans based on Eclipse was less than that of VMAT plans based on Pinnacle,without statistical differences(P>0.05).For patients with rectal cancer,the monitor units,the conformity index and homogeneity index of planning target area were similar between VMAT plans based on Eclipse and VMAT plans based on Pinnacle,so was the protection of bladder and small intestine.However,the V40 of femur-L and femur-R in VMAT plans based on Eclipse for rectal cancer were superior to that in VMAT plans based on Pinnacle,without statistical differences(P>0.05).Under the criteria of 3%/3 mm and 2%/2 mm,the Gamma passing rates of VMAT plans based on Eclipse were higher than those of VMAT plans based on Pinnacle for laryngeal and rectal cancers,and the differences were statistically significant(P<0.05).Conclusion Although the plan quality and dose verification of VMAT plans based on Eclipse and Pinnacle can satisfy the requirements of clinical treatment,there is a slight difference in the passing rates of dose verification and monitor units.Further investigations should be conducted in more cases to explore the reasons for the differences.