Abstract：
Dose-averaged linear energy transfer (LETd) is conventionally evaluated from the relative biological effectiveness (RBE)-LETd fitted function used in the treatment planning system. In this study, we calculated the physical doses and their linear energy transfer (LET) distributions for patterns of typical CIRT beams using Monte Carlo (MC) simulation. The LETd was then deduced from the MC simulation and compared with that obtained from the conventional method. The two types of LETd agreed well with each other, except around the distal end of the spread-out Bragg peak. Furthermore, an MC simulation was conducted with the material composition of water and realistic materials. The profiles of physical dose and LETd were in good agreement for both techniques. These results indicate that the previous studies to analyze the minimum LETd in CIRT cases are valid for practical situations, and the material composition conversion to water little affects the dose distribution in the irradiation field.
摘要：
剂量平均线性能量转移(LETd)通常根据治疗计划系统中使用的相对生物有效性(RBE)-LETd拟合函数来评估。在这项研究中,我们使用蒙特卡罗（MC）模拟计算了典型CIRT光束模式的物理剂量及其线性能量转移（LET）分布。然后从MC模拟中推导出LETd，并将其与常规方法获得的LETd进行比较。两种类型的LETd彼此非常吻合，除了展开的布拉格峰的远端周围。此外，对水和现实材料的材料组成进行了MC模拟。两种技术的物理剂量和LETd的分布非常一致。这些结果表明，先前分析CIRT病例中最小LETd的研究对于实际情况是有效的，材料成分向水的转化对辐照场的剂量分布影响不大。
