Pietrzak Marcin, Mietelska Monika, Bancer Aleksandr, Rucinski Antoni, Brzozowska Beata
National Centre for Nuclear Research, Świerk, Poland.
Biomedical Physics Division, Faculty of Physics, University of Warsaw, Warsaw, Poland.
Phys Med Biol. 2021 Nov 11;66(22). doi: 10.1088/1361-6560/ac33eb.
The purpose of this work was to validate the calculation accuracy of nanodosimetric quantities in Geant4-DNA track structure simulation code. We implemented the Jet Counter (JC) nanodosimeter geometry in the simulation platform and quantified the impact of the Geant4-DNA physics models and JC detector performance on the ionization cluster size distributions (ICSD). ICSD parameters characterize the quality of radiation field and are supposed to be correlated to the complexity of the initial DNA damage in nanoscale and eventually the response of biological systems to radiation. We compared Monte Carlo simulations of ICSD in JC geometry performed using Geant4-DNA and PTra codes with experimental data collected for alpha particles at 3.8 MeV. We investigated the impact of simulation and experimental settings, i.e., three Geant4-DNA physics models, three sizes of a nanometer sensitive volume, gas to water density scaling procedure, JC ion extraction efficiency and the presence of passive components of the detector on the ICSD and their parameters. We found that ICSD in JC geometry obtained from Geant4-DNA simulations in water correspond well to ICSD measurements in nitrogen gas for all investigated settings, while the best agreement is for Geant4-DNA physics option 4. This work also discusses the accuracy and robustness of ICSD parameters in the context of the application of track structure simulation methods for treatment planning in particle therapy.
这项工作的目的是验证Geant4-DNA径迹结构模拟代码中纳米剂量学量的计算准确性。我们在模拟平台中实现了喷射计数器（JC）纳米剂量计几何结构，并量化了Geant4-DNA物理模型和JC探测器性能对电离簇尺寸分布（ICSD）的影响。ICSD参数表征了辐射场的质量，并且应该与纳米尺度上初始DNA损伤的复杂性相关，最终与生物系统对辐射的响应相关。我们将使用Geant4-DNA和PTra代码在JC几何结构中对ICSD进行的蒙特卡罗模拟与在3.8 MeV下针对α粒子收集的实验数据进行了比较。我们研究了模拟和实验设置的影响，即三种Geant4-DNA物理模型、三种纳米敏感体积大小、气体与水的密度缩放程序、JC离子提取效率以及探测器无源组件的存在对ICSD及其参数的影响。我们发现，在所有研究设置下，从水中的Geant4-DNA模拟获得的JC几何结构中的ICSD与氮气中的ICSD测量结果吻合良好，而与Geant4-DNA物理选项4的吻合度最佳。这项工作还在粒子治疗治疗计划的径迹结构模拟方法应用的背景下讨论了ICSD参数的准确性和稳健性。
