Application of a simple DNA damage model developed for electrons to proton irradiation
Application of a simple DNA damage model developed for electrons to proton irradiation
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DOI：
10.1088/1361-6560/ac9a20
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发表时间：
2022-11-07
影响因子：
3.5
通讯作者：
Sato, Tatsuhiko
中科院分区：
文献类型：
--
作者：
Matsuya, Yusuke;Kai, Takeshi;Sato, Tatsuhiko
质子束治疗允许照射肿瘤体积，相对于常规X射线放射疗法，对正常组织的副作用减少。质子束照射后的细胞杀伤等生物学效应取决于质子动能，而质子动能与早期DNA损伤诱导有本质联系。因此，基于蒙特卡罗模拟的DNA损伤估计是一个世界性的研究课题。这种模拟是研究DNA链断裂形成机制的一种手段。然而，过去考虑化学过程和DNA结构的建模需要很长的计算时间。粒子和重离子输运系统（PHITS）是一种通用的蒙特卡罗程序，它可以模拟质子的径迹结构，但不能模拟液态水中的自由基动力学。它还包括一个简单的模型，使有效的估计DNA损伤产量仅从空间分布的电离和激发没有DNA的几何形状，这是最初开发的电子轨道结构模拟。在这项研究中，我们研究了该模型的潜在应用质子没有任何修改。单链断裂，双链断裂（DSB）和复杂的DSB的产率作为质子动能的函数进行了评估。基于PHITS的估计表明，DSB产量增加的线性能量转移（LET）的增加，并再现了各种DNA损伤类型的LET高达约30 keV μ m（-1）的质子诱导的实验和模拟产量。这些结果表明，目前的DNA损伤模型实施PHITS是足以估计质子照射后诱导的DNA损伤产量，除了在非常低的能量（低于1兆电子伏）。该模型有助于评价放射治疗中的早期生物学影响。
Proton beam therapy allows irradiating tumor volumes with reduced side effects on normal tissues with respect to conventional x-ray radiotherapy. Biological effects such as cell killing after proton beam irradiations depend on the proton kinetic energy, which is intrinsically related to early DNA damage induction. As such, DNA damage estimation based on Monte Carlo simulations is a research topic of worldwide interest. Such simulation is a mean of investigating the mechanisms of DNA strand break formations. However, past modellings considering chemical processes and DNA structures require long calculation times. Particle and heavy ion transport system (PHITS) is one of the general-purpose Monte Carlo codes that can simulate track structure of protons, meanwhile cannot handle radical dynamics simulation in liquid water. It also includes a simple model enabling the efficient estimation of DNA damage yields only from the spatial distribution of ionizations and excitations without DNA geometry, which was originally developed for electron track-structure simulations. In this study, we investigated the potential application of the model to protons without any modification. The yields of single-strand breaks, double-strand breaks (DSBs) and the complex DSBs were assessed as functions of the proton kinetic energy. The PHITS-based estimation showed that the DSB yields increased as the linear energy transfer (LET) increased, and reproduced the experimental and simulated yields of various DNA damage types induced by protons with LET up to about 30 keV mu m(-1). These results suggest that the current DNA damage model implemented in PHITS is sufficient for estimating DNA lesion yields induced after protons irradiation except at very low energies (below 1 MeV). This model contributes to evaluating early biological impacts in radiation therapy.