容积旋转调强计划计算分辨率对COMPASS验证通过率的影响  

The impact of dose grid resolution during VMAT planning on COMPASS pass rate

作　　者：李娜[1] 冯革[1] 张旭[1] 尹策[1] 李黎 贾明轩[1] Li Na;Feng Ge;Zhang Xu;Yin Ce;Li Li;Jia Mingxuan(Department of Radiation Therapy,Shengjing Hospital Affiliated to China Medical University,Shenyang 110023,China)

机构地区：[1]中国医科大学附属盛京医院放射治疗室,沈阳110023

出　　处：《中华放射医学与防护杂志》2018年第10期761-766,共6页Chinese Journal of Radiological Medicine and Protection

摘　　要：目的 研究容积旋转调强放疗（VMAT）计划设计采用不同计算分辨率对COMPASS验证通过率的影响。方法 选取10例宫颈癌术后患者，在治疗计划系统上采用4种计算分辨率0.2 cm×0.2 cm×0.2 cm、0.3 cm×0.3 cm×0.3 cm、0.4 cm×0.4 cm×0.4 cm、0.5 cm×0.5 cm×0.5 cm设计VMAT治疗计划。计划传至加速器上执行，由COMPASS实际测量重建并与TPS优化的剂量分布进行比较得到每个计划的偏差值，统计分析4种计划的偏差值是否有统计学意义。结果 肿瘤靶区的Dmean和D95，COMPASS测量重建结果表明Dmean偏差值的平均值〈0.5%，D95〈1.3%，标准差均〈1.0%。对于4种计划危及器官（OAR），其中左右股骨头的Dmean偏差值最大可达-6.7%、-7.0%、-8.0%、-5.8%，直肠V35偏差值最大可达-4.9%、-6.3%、-6.1%、-5.7%，是OAR中相应参数偏差值最大的两个器官。肿瘤靶区的γ通过率都在95%以上，标准差不超过2.5%；OAR除了股骨头γ通过率略低，在95%以上，标准差1.9%~6.1%不等，其余都达到98%以上，标准差〈2.5%，差异均无统计学意义（P〉0.05）。平均γ值的分析结果与γ通过率相一致，除了股骨头的平均γ值〉0.4外，PTV和其余OAR的平均γ值都〈0.4，差异均无统计学意义（P〉0.05）。结论 采用0.2~0.5 cm计算分辨率优化宫颈癌术后VMAT计划，不影响COMPASS验证通过率。Objective To investigate the impact of adopting different dose grid resolution during volumetric modulated arc therapy （VMAT） planning on COMPASS pass rate. Methods A total of 10 patients with cervical cancer were enrolled. Four types of VMAT plans （plan1, plan2, plan3, plan4） were designed for each patient, with dose grid resolution of 0.2 cm×0.2 cm×0.2 cm, 0.3 cm×0.3 cm×0.3 cm, 0.4 cm×0.4 cm×0.4 cm and 0.5 cm×0.5 cm×0.5 cm, respectively. The plans were exported to Linac and conducted, then measured by COMPASS. The discrepancies were analyzed, which were obtained by comparing reconstructed dose from COMPASS and dose from TPS optimization. Results For tumor volume, the mean value of Dmean and D95 were 〈0.5% and 〈1.3% respectively, and the standard deviation were both 〈1.0%. For organs at risk （OAR）, the max discrepancies were Dmean of femur with -6.7%, -7.0%, -8.0%, -5.8%, and V35 of rectum with 4.9%, -6.3%, -6.1%, -5.7% in four types of VMAT plans. The γ （3%, 3 mm） rate of tumor volume was 〉95% with standard deviation 〈2.5%, with no statistically significant difference among the four types of plans （P〉0.05）. The γ （3%,3 mm） rate of OARs were 〉98% except femur （〉95%）, and the standard deviations were within 1.9%-6.1%, with no statistical significance （P〉0.05）. The average γ rate of tumor volume and OARs were 〈0.4 except femur （〉0.4）, with no statistically significant difference among four types of VMAT plans （P〉0.05）. Conclusions COMPASS pass rate was not influenced by the dose grid resolution between 0.2~0.5 cm for VMAT plan.

关 键 词：容积旋转调强放疗 计算分辨率 验证通过率 

分 类 号：R730.55[医药卫生—肿瘤]