Bias Dose在脑转移肿瘤序贯放疗计划设计中的应用

Application of Bias Dose in sequential radiotherapy planning of brain metastases

目的:分析医科达Monaco计划系统的Bias Dose计划设计功能应用于脑转移肿瘤的序贯放疗计划设计的可行性及优缺点。方法:选择10例脑转移肿瘤患者,以同一首程计划为基础,分别使用常规方法和Bias方法(采用Bias Dose计划设计功能)设计再程计划,作为常规计划组和Bias计划组,比较2组计划的剂量分布情况、机器跳数及计划设计时间(包括优化时间和预估执行时间)。使用SPSS 22.0软件进行统计学分析。结果:相较于常规计划组,Bias计划组计划肿瘤区(planning gross tumor volume,PGTV)的D2偏高0.64%,计划靶区(planning target volume,PTV)的Dmean偏低1.18%,差异均具有统计学意义(P<0.05),且结果均在临床可接受范围。2组计划靶区覆盖率均在96%以上,危及器官受量均在临床限值内,差异均无统计学意义(P>0.05)。Bias计划组的适形性指数、PGTV靶区的均匀性指数、机器跳数和预估执行时间均高于常规计划组,PTV靶区的均匀性指数低于常规计划组,差异均具有统计学意义(P<0.05)。结论:应用Bias Dose计划设计功能设计脑转移肿瘤序贯放疗计划,虽然在机器跳数和预估执行时间方面有一定的劣势,但在靶区剂量分布方面具有一定的优势,同时也给计划设计和评估带来很大便利,因此在脑转移肿瘤序贯放疗中应采用Bias Dose计划设计功能以取得更优的剂量分布。

Objective To analyze the feasibility, advantages and disadvantages of Bias Dose planning of Elekta Monaco planning system in the design of sequential radiotherapy plans for brain metastatic tumors. Methods Ten patients with brain metastatic tumors were selected and the same first course plan was used as the background dose. The re-course plans of the patients were designed with the conventional method and Bias method respectively and enrolled into a conventional plan group and a Bias plan group. The dose distribution, monitor unit and plan design time were compared between the two groups.Statistical analysis was performed using SPSS 22.0 software. Results When compared with the conventional plan group the Bias plan group had the D2value of the planning gross tumor volume(PGTV) 0.64% higher, the Dmeanvalue of the planning target volume(PTV) 1.18% lower, both with statistically significant differences(P<0.05) and the results within the clinically acceptable range. The two groups both had the PTV coverages higher than 96% and the doses to the organs at risk within the clinical limit, and none of the differences was statistically significant(P>0.05). The Bias plan group had the conformity index,homogeneity index of PGTV, monitor unit and estimated execution time all higher than those of the conventional plan group,while the homogeneity index of PTV lower, with all the differences being statistically significant(P<0.05). Conclusion Bias Dose planning function involved in the design of sequential radiotherapy plans for brain metastatic tumors has disadvantages in monitor unit and estimated execution time, while gains advantages in PTV dose distribution and facilitates the plan design and evaluation greatly, and thus Bias Dose planning has to be adopted in the design of sequential radiotherapy plans for brain metastatic tumors to obtain optimized dose distribution.