Polopetrakis Ioannis, Kyriakou Ioanna, Sakata Dousatsu, Tran Hoang N, Ivanchenko Vladimir N, Karaiskos Pantelis, Guatelli Susanna, Incerti Sebastien, Emfietzoglou Dimitris
Medical Physics Laboratory, Department of Medicine, University of Ioannina, Ioannina 45110, Greece.
Division of Health Sciences, University of Osaka, Osaka, Japan.
Phys Med Biol. 2025 Aug 14;70(16). doi: 10.1088/1361-6560/adf40c.
To develop a new Geant4-DNA physics model for electron track-structure simulations in gold nanoparticles (AuNPs) that overcomes important deficiencies of the current default model and is applicable over a broad energy range from 10 eV to 1 MeV.A model of the energy-loss-function of solid-Au with parameters optimized by optical data and self-consistency tests is presented and used to calculate inelastic cross sections using the relativistic plane wave Born approximation (RPWBA). Low-energy corrections for non-Born effects are included and a practical approximation to the Landau damping mechanism of plasmon decay is proposed that accounts for secondary electron production and facilitates its application to Monte Carlo (MC) track-structure simulations.Calculations of inelastic cross sections and stopping power (SP) values for the individual ionization and excitation channels of solid-Au are presented and compared against the current default model of Geant4-DNA (DNA_AU_2016), the Livermore and Penelope low-energy models of Geant4, and other published models. It is shown that the present model improves the current default model of Geant4-DNA by offering almost excellent agreement (∼2% on average) with NIST's SP data (previously at ∼6%), while eliminating the unphysical low-energy overestimation (up to 1000% or more), thus, bringing much better agreement with more elaborate physics models for solid-Au.MC track-structure codes are considered the gold standard for dose enhancement calculations in AuNP-aided radiotherapy. In particular, the Geant4-DNA toolkit offers functionalities for simulating critical cellular radiobiological effects following AuNP irradiation. Yet the accuracy of such simulations is limited by the quality of the cross sections for the individual electron-AuNP interactions. It is envisioned that the present model will allow Geant4-DNA users to perform more accurate simulations of electron transport within AuNPs and better quantify the outgoing secondary electron spectrum which is responsible for the dose enhancement effect and subsequent radiobiological damage.
开发一种新的用于金纳米颗粒（AuNPs）中电子径迹结构模拟的Geant4-DNA物理模型，该模型克服了当前默认模型的重要缺陷，并且适用于从10 eV到1 MeV的宽能量范围。提出了一种通过光学数据和自洽测试优化参数的固态金能量损失函数模型，并使用相对论平面波玻恩近似（RPWBA）来计算非弹性截面。包括了对非玻恩效应的低能修正，并提出了一种对等离子体激元衰变的朗道阻尼机制的实用近似，该近似考虑了二次电子产生，并便于将其应用于蒙特卡罗（MC）径迹结构模拟。给出了固态金各个电离和激发通道的非弹性截面和阻止本领（SP）值的计算结果，并与Geant4-DNA的当前默认模型（DNA_AU_2016）、Geant4的利弗莫尔和佩内洛普低能模型以及其他已发表的模型进行了比较。结果表明，本模型通过与美国国家标准与技术研究院（NIST）的SP数据几乎具有极佳的一致性（平均约2%，之前约为6%）改进了Geant4-DNA的当前默认模型，同时消除了非物理的低能高估（高达1000%或更高），从而与更精细的固态金物理模型具有更好的一致性。MC径迹结构代码被认为是金纳米颗粒辅助放射治疗中剂量增强计算的金标准。特别是，Geant4-DNA工具包提供了模拟金纳米颗粒辐照后关键细胞放射生物学效应的功能。然而，这种模拟的准确性受到单个电子与金纳米颗粒相互作用截面质量的限制。可以设想，本模型将使Geant4-DNA用户能够对金纳米颗粒内的电子传输进行更准确的模拟，并更好地量化导致剂量增强效应和后续放射生物学损伤的出射二次电子能谱。
