摘要目的 研究射波刀治疗计划系统的不同剂量算法应用于肺部肿瘤计划剂量计算结果的差异,分析肿瘤体积、位置等因素对计算结果的影响.方法 选取2017年肺部肿瘤病例32例,针对每一病例使用射波刀VSI系统配备的MultiPlan 5.2.1计划系统设计计划,分别采取射线追踪算法和蒙特卡罗算法计算剂量分布,比较两种算法剂量计算结果.结果 据现有病例,两种算法剂量计算结果显示:计划靶区的处方覆盖率、适形指数、新适形指数、均匀性指数的偏差范围分别为0.93%~68. 80%、 0.87%~17. 21%、-212.38%~8. 27%、 0%~15. 17%.结论 射波刀治疗计划系统设计肺部肿瘤计划,肿瘤体积、位置对不同算法剂量计算结果的差异性有较大影响,越小的肿瘤体积、越长的射束异质性路径易于产生更大的差异性,应采用或参考蒙特卡罗算法的计算结果开展治疗.

abstractsObjective To evaluate the effect of the discrepancy of the dose calculation results of different algorithms upon the CyberKnife lung tumor treatment plan,and assess the impact of tumor volume and location on the dose calculation results. Methods Thirty-two cases of lung tumors were treated with MultiPlan 5.2.1 planning system of CyberKnife VSI.Ray Tracing and Monte Carlo algorithms were adopted to calculate the dose distribution, and then the calculation results were statistically compared between two algorithms. Results For the enrolled cases,the calculation results of these two algorithms demonstrated that the deviation range of prescription dose coverage of planning target volume (PTV),conformal index,new conformal index and uniformity index were 0.93%~68. 80%, 0.87%~17. 21%,-212.38%~8. 27% and 0%~15. 17%, respectively. Conclusions In the CyberKnife treatment of lung tumors, the volume and location of tumors exert significant impact on the discrepancies of the dose calculation results of different algorithms. The smaller tumor volume and longer beam heterogeneity path are likely to generate a greater discrepancy. It is recommended to adopt or refer to the calculation results of Monte Carlo algorithm to deliver corresponding treatment.