Biological Dose Estimation for Charged-Particle Therapy Using an Improved PHITS Code Coupled with a Microdosimetric Kinetic Model
Biological Dose Estimation for Charged-Particle Therapy Using an Improved PHITS Code Coupled with a Microdosimetric Kinetic Model
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DOI：
10.1667/rr1510.1
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发表时间：
2009-01-01
影响因子：
3.4
通讯作者：
Sihver, Lembit
中科院分区：
文献类型：
--
作者：
Sato, Tatsuhiko;Kase, Yuki;Sihver, Lembit
与 LET 相比，线能 y 等微剂量量是表达 HZE 粒子 RBE 的更好指标。然而，由于难以计算宏观物质中的概率密度，微剂量量在计算剂量测定中的使用受到严重限制。因此，我们改进了粒子输运模拟代码PHITS，通过结合数学函数，使其具有在宏观框架中估计微观剂量学概率密度的能力，该数学函数可以即时计算HZE粒子轨迹周围的概率密度，其精度相当于微观轨道结构模拟的精度。使用改进的 PHITS 与微剂量动力学模型相结合，建立了一种估计带电粒子治疗的生物剂量（物理剂量和 RBE 的乘积）的新方法。通过将计算出的物理剂量和RBE值与在几种HZE粒子照射的平板体模上测量的相应数据进行比较，检验了该方法估算的生物剂量的准确性。本研究建立的模拟技术将有助于优化带电粒子治疗的治疗计划，从而最大限度地提高对肿瘤的治疗效果，同时最大限度地减少对周围正常组织的意外有害影响。 (C) 2009 年放射线研究会
Microdosimetric quantities such as lineal energy, y, are better indexes for expressing the RBE of HZE particles in comparison to LET. However, the use of microdosimetric quantities in computational dosimetry is severely limited because of the difficulty in calculating their probability densities in macroscopic matter. We therefore improved the particle transport simulation code PHITS, providing it with the capability of estimating the microdosimetric probability densities in a macroscopic framework by incorporating a mathematical function that can instantaneously calculate the probability densities around the trajectory of HZE particles with a precision equivalent to that of a microscopic track-structure simulation. A new method for estimating biological dose, the product of physical dose and RBE, from charged-particle therapy was established using the improved PHITS coupled with a microdosimetric kinetic model. The accuracy of the biological dose estimated by this method was tested by comparing the calculated physical doses and RBE values with the corresponding data measured in a slab phantom irradiated with several kinds of HZE particles. The simulation technique established in this study will help to optimize the treatment planning of charged-particle therapy, thereby maximizing the therapeutic effect on tumors while minimizing unintended harmful effects on surrounding normal tissues. (C) 2009 by Radiation Research Society