使用 Geant4-DNA 定量估计重离子布拉格峰能区下水辐射分解产物的轨迹段产额。

Quantitative estimation of track segment yields of water radiolysis species under heavy ions around Bragg peak energies using Geant4-DNA.

机构信息

Graduate School of Biomedical Science and Engineering, Hokkaido University, Kita-15 Nishi-7, Kita-ku, Sapporo, Hokkaido, 060-8638, Japan.

National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.

出版信息

Sci Rep. 2021 Jan 15;11(1):1524. doi: 10.1038/s41598-021-81215-6.

DOI:10.1038/s41598-021-81215-6

PMID:33452450

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC7810756/

Abstract

We evaluate the track segment yield G' of typical water radiolysis products (e, OH and HO) under heavy ions (He, C and Fe ions) using a Monte Carlo simulation code in the Geant4-DNA. Furthermore, we reproduce experimental results of OH of He and C ions around the Bragg peak energies (< 6 MeV/u). In the relatively high energy region (e.g., > 10 MeV/u), the simulation results using Geant4-DNA have agreed with experimental results. However, the G-values of water radiolysis species have not been properly evaluated around the Bragg peak energies, at which high ionizing density can be expected. Around the Bragg peak energy, dense continuous secondary products are generated, so that it is necessary to simulate the radical-radical reaction more accurately. To do so, we added the role of secondary products formed by irradiation. Consequently, our simulation results are in good agreement with experimental results and previous simulations not only in the high-energy region but also around the Bragg peak. Several future issues are also discussed regarding the roles of fragmentation and multi-ionization to realize more realistic simulations.

摘要

我们使用 Geant4-DNA 中的蒙特卡罗模拟代码评估重离子（氦、碳和铁离子）下典型水辐射分解产物（电子、羟基和氢氧自由基）的轨迹片段产额 G'。此外，我们重现了氦和碳离子在布拉格峰能量（<6 MeV/u）附近的 OH 实验结果。在相对较高的能量区域（例如，>10 MeV/u），使用 Geant4-DNA 的模拟结果与实验结果一致。然而，在布拉格峰能量附近，水辐射分解产物的 G 值尚未得到适当评估，因为在这个区域可以预期会有高的离子密度。在布拉格峰能量附近，会产生密集的连续二次产物，因此需要更准确地模拟自由基-自由基反应。为此，我们添加了辐照形成的次级产物的作用。因此，我们的模拟结果不仅在高能区域，而且在布拉格峰附近，都与实验结果和以前的模拟结果非常吻合。还讨论了关于碎片和多电离的几个未来问题，以实现更现实的模拟。