Jang Si Young, Lalonde Ron, Ozhasoglu Cihat, Burton Steven, Heron Dwight, Huq M Saiful
The University of Pittsburgh Cancer Institute.
J Appl Clin Med Phys. 2016 Sep 8;17(5):184-199. doi: 10.1120/jacmp.v17i5.6260.
We performed an evaluation of the CyberKnife InCise MLC by comparing plan qualities for single and multiple brain lesions generated using the first version of InCise MLC, fixed cone, and Iris collimators. We also investigated differences in delivery efficiency among the three collimators. Twenty-four patients with single or multiple brain mets treated previously in our clinic on a CyberKnife M6 using cone/Iris collimators were selected for this study. Treatment plans were generated for all lesions using the InCise MLC. Number of monitor units, delivery time, target coverage, conformity index, and dose falloff were compared between MLC- and clinical cone/Iris-based plans. Statistical analysis was performed using the non-parametric Wilcoxon-Mann-Whitney signed-rank test. The planning accuracy of the MLC-based plans was validated using chamber and film measurements. The InCise MLC-based plans achieved mean dose and target coverage comparable to the cone/Iris-based plans. Although the conformity indices of the MLC-based plans were slightly higher than those of the cone/Iris-based plans, beam delivery time for the MLC-based plans was shorter by 30% ~ 40%. For smaller targets or cases with OARs located close to or abutting target volumes, MLC-based plans provided inferior dose conformity compared to cone/Iris-based plans. The QA results of MLC-based plans were within 5% absolute dose difference with over 90% gamma passing rate using 2%/2 mm gamma criteria. The first version of InCise MLC could be a useful delivery modality, especially for clinical situations for which delivery time is a limiting factor or for multitarget cases.
我们通过比较使用第一代InCise多叶准直器、固定准直器和虹膜准直器生成的单发性和多发性脑病变的计划质量，对赛博刀InCise多叶准直器进行了评估。我们还研究了三种准直器在射束输出效率方面的差异。本研究选取了24例此前在我们诊所使用准直器/虹膜准直器在赛博刀M6上接受治疗的单发或多发脑转移瘤患者。使用InCise多叶准直器为所有病变生成治疗计划。比较了基于多叶准直器的计划与基于临床准直器/虹膜的计划之间的监测单位数量、射束输出时间、靶区覆盖情况、适形指数和剂量跌落。使用非参数Wilcoxon-Mann-Whitney符号秩检验进行统计分析。基于多叶准直器的计划的计划准确性通过电离室和胶片测量进行验证。基于InCise多叶准直器的计划所实现的平均剂量和靶区覆盖与基于准直器/虹膜的计划相当。虽然基于多叶准直器的计划的适形指数略高于基于准直器/虹膜的计划，但基于多叶准直器的计划的射束输出时间缩短了30%至40%。对于较小的靶区或周围有危及器官且靠近或邻接靶区的病例，与基于准直器/虹膜的计划相比，基于多叶准直器的计划的剂量适形性较差。基于多叶准直器的计划的质量保证结果在绝对剂量差异5%以内，使用2%/2mm的γ标准时γ通过率超过90%。第一代InCise多叶准直器可能是一种有用的射束输出方式，特别是对于射束输出时间是限制因素的临床情况或多靶区病例。
