Japan Atomic Energy Agency (JAEA), Nuclear Science and Engineering Center, Research Group for Radiation Transport Analysis, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan.
Particle Radiation Biology, Department of Radiation Life and Medical Science, Research Reactor Institute, Kyoto University, 2-1010 Asashiro-nishi, Kumatori, Sennan, Osaka, 590-0494, Japan.
Sci Rep. 2018 Jan 17;8(1):988. doi: 10.1038/s41598-017-18871-0.
We here propose a new model for estimating the biological effectiveness for boron neutron capture therapy (BNCT) considering intra- and intercellular heterogeneity in B distribution. The new model was developed from our previously established stochastic microdosimetric kinetic model that determines the surviving fraction of cells irradiated with any radiations. In the model, the probability density of the absorbed doses in microscopic scales is the fundamental physical index for characterizing the radiation fields. A new computational method was established to determine the probability density for application to BNCT using the Particle and Heavy Ion Transport code System PHITS. The parameters used in the model were determined from the measured surviving fraction of tumor cells administrated with two kinds of B compounds. The model quantitatively highlighted the indispensable need to consider the synergetic effect and the dose dependence of the biological effectiveness in the estimate of the therapeutic effect of BNCT. The model can predict the biological effectiveness of newly developed B compounds based on their intra- and intercellular distributions, and thus, it can play important roles not only in treatment planning but also in drug discovery research for future BNCT.
我们在这里提出了一种新的模型，用于估计硼中子俘获治疗（BNCT）的生物效应，同时考虑了 B 分布的细胞内和细胞间异质性。该新模型是从我们之前建立的随机微观剂量动力学模型发展而来的，该模型确定了任何辐射照射的细胞的存活分数。在该模型中，微观尺度上吸收剂量的概率密度是用于描述辐射场的基本物理指标。建立了一种新的计算方法，以使用粒子和重离子输运代码系统 PHITS 确定概率密度以应用于 BNCT。模型中使用的参数是根据用两种 B 化合物处理的肿瘤细胞的测量存活分数确定的。该模型定量地强调了在估计 BNCT 的治疗效果时，必须考虑协同作用和生物效应的剂量依赖性。该模型可以根据新开发的 B 化合物的细胞内和细胞间分布来预测其生物效应，因此，它不仅可以在治疗计划中发挥重要作用，而且可以在未来 BNCT 的药物发现研究中发挥重要作用。
