Technical Note: Improvements in geant4 energy-loss model and the effect on low-energy electron transport in liquid water
Technical Note: Improvements in geant4 energy-loss model and the effect on low-energy electron transport in liquid water
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DOI：
10.1118/1.4921613
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发表时间：
2015-07-01
期刊：
影响因子：
3.8
通讯作者：
Francis, Z.
中科院分区：
文献类型：
--
作者：
Kyriakou, I.;Incerti, S.;Francis, Z.
目的：GEANT 4-DNA物理模型通过一组更准确的液态水中电离和激发电子横截面进行升级。低能量的电子输运模拟的GEANT 4蒙特卡罗工具包的新发展的影响进行检查，以提高其性能的剂量学应用在亚细胞和纳米level.Methods：作者提供了一种算法的改进实施的Emfietzoglou模型中使用的GEANT 4-DNA现有模型的液态水的介电响应函数。该算法重新分配介电函数的虚部，以确保结合能处的物理动机行为，同时保留原始公式的所有优点，例如，分析性质和f和规则的实现。结果：新模型的电离截面和激发截面与现有模型的结果有很大的不同。特别是，相对于电离，激发被强烈增强，导致在亚keV电子能量下具有更高的W值和更少的扩散剂量点核。结论：低能电子激发和电离液态水的改进能量损失模型已在GEANT 4-DNA中实现。由于介电函数的不同划分，剂量点核中可疑的低W值和非物理的长尾已被校正。(C)2015年美国医学物理学家协会。
Purpose: The GEANT4-DNA physics models are upgraded by a more accurate set of electron cross sections for ionization and excitation in liquid water. The impact of the new developments on low-energy electron transport simulations by the GEANT4 Monte Carlo toolkit is examined for improving its performance in dosimetry applications at the subcellular and nanometer level.Methods: The authors provide an algorithm for an improved implementation of the Emfietzoglou model dielectric response function of liquid water used in the GEANT4-DNA existing model. The algorithm redistributes the imaginary part of the dielectric function to ensure a physically motivated behavior at the binding energies, while retaining all the advantages of the original formulation, e.g., the analytic properties and the fulfillment of the f-sum-rule. In addition, refinements in the exchange and perturbation corrections to the Born approximation used in the GEANT4-DNA existing model are also made.Results: The new ionization and excitation cross sections are significantly different from those of the GEANT4-DNA existing model. In particular, excitations are strongly enhanced relative to ionizations, resulting in higher W-values and less diffusive dose-point-kernels at sub-keV electron energies.Conclusions: An improved energy-loss model for the excitation and ionization of liquid water by low-energy electrons has been implemented in GEANT4-DNA. The suspiciously low W-values and the unphysical long tail in the dose-point-kernel have been corrected owing to a different partitioning of the dielectric function. (C) 2015 American Association of Physicists in Medicine.