Flagged uniform particle splitting for variance reduction in proton and carbon ion track-structure simulations.
Flagged uniform particle splitting for variance reduction in proton and carbon ion track-structure simulations.
复制标题
标记的统一粒子拆分，以减少质子和碳离子轨道结构模拟的方差。
DOI：
10.1088/1361-6560/aa7831
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发表时间：
2017-07-06
影响因子：
3.5
通讯作者：
Faddegon B
中科院分区：
文献类型：
--
作者：
Ramos-Méndez J;Schuemann J;Incerti S;Paganetti H;Schulte R;Faddegon B
为了提高TOPAS-nBio蒙特卡罗径迹结构模拟的计算效率，采用两种方法实现了标记均匀粒子分裂，通过提高电离事件中二次电子的产生来提高计算效率。在方法1中，修改了Geant 4内核。在方法2中，Geant 4未被修改。在这两种方法中，分配给每个新分裂电子的唯一标记号被其后代继承，允许重新分类分裂事件，就好像是由独立的历史产生的。计算效率和准确性进行了评估，为模拟0.5-20 MeV质子和1-20 MeV/u碳离子的三个端点：（1）平均的电离团簇大小分布，（2）平均数的DNA单链断裂（SSB）和双链断裂（DSB）与DBSCAN分类，和（3）平均数的SSB和DSB分类与基于几何的算法。对于终点（1），当分裂由初级粒子的直接电离事件产生的电子时，模拟效率比当分裂由次级电子的第一电离事件产生的电子时低3倍。选择后一种技术进行进一步研究。以下结果是方法2的结果，方法1的相对效率低约4.5倍。对于终点（1），在128分裂电子处的相对效率接近最大值，对于质子，相对效率随着能量从47.2±0.2增加到66.9±0.2，对于碳，相对效率随着能量从51.3±0.4减少到41.7±0.2。对于终点（2），相对效率随能量增加而增加，质子从20.7±0.1增加到50.2±0.3，碳从15.6±0.1增加到20.2±0.1。对于终点（3），相对效率随能量增加而增加，质子从31.0±0.2增加到58.2±0.4，碳从23.9±0.1增加到26.2±0.2。对于终点（1）和（2），有和无分割的模拟结果在1%（2个标准差）内一致，对于终点（3），在2%（1个标准差）内一致。总之，标准粒子分裂方差减少技术可以成功地实施在蒙特卡罗轨道结构代码。
Flagged uniform particle splitting was implemented with two methods to improve the computational efficiency of Monte Carlo track structure simulations with TOPAS-nBio by enhancing the production of secondary electrons in ionization events. In Method 1 the Geant4 kernel was modified. In Method 2 Geant4 was not modified. In both methods a unique flag number assigned to each new split electron was inherited by its progeny, permitting reclassification of the split events as if produced by independent histories. Computational efficiency and accuracy were evaluated for simulations of 0.5–20 MeV protons and 1–20 MeV/u carbon ions for three endpoints: (1) mean of the ionization cluster size distribution, (2) mean number of DNA single-strand breaks (SSBs) and double-strand breaks (DSBs) classified with DBSCAN, and (3) mean number of SSBs and DSBs classified with a geometry-based algorithm. For endpoint (1), simulation efficiency was 3 times lower when splitting electrons generated by direct ionization events of primary particles than when splitting electrons generated by the first ionization events of secondary electrons. The latter technique was selected for further investigation. The following results are for Method 2, with relative efficiencies about 4.5 times lower for Method 1. For endpoint (1), relative efficiency at 128 split electrons approached maximum, increasing with energy from 47.2±0.2 to 66.9±0.2 for protons, decreasing with energy from 51.3±0.4 to 41.7±0.2 for carbon. For endpoint (2), relative efficiency increased with energy, from 20.7±0.1 to 50.2±0.3 for protons, 15.6±0.1 to 20.2±0.1 for carbon. For endpoint (3) relative efficiency increased with energy, from 31.0±0.2 to 58.2±0.4 for protons, 23.9±0.1 to 26.2±0.2 for carbon. Simulation results with and without splitting agreed within 1% (2 standard deviations) for endpoints (1) and (2), within 2% (1 standard deviation) for endpoint (3). In conclusion, standard particle splitting variance reduction techniques can be successfully implemented in Monte Carlo track structure codes.
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影响因子：
3.8
作者：
Kyriakou, I.;Incerti, S.;Francis, Z.
通讯作者：
Francis, Z.
影响因子：
2.6
作者：
GOODHEAD, DT
通讯作者：
GOODHEAD, DT
影响因子：
2.6
作者：
Nikjoo, H;ONeill, P;Terrissol, M
通讯作者：
Terrissol, M
影响因子：
3.8
作者：
Incerti, S.;Ivanchenko, A.;Zacharatou, C.
通讯作者：
Zacharatou, C.
DOI：
10.1016/j.ejmp.2016.12.010
发表时间：
2017-01
期刊：
Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB)
影响因子：
--
作者：
McNamara A;Geng C;Turner R;Mendez JR;Perl J;Held K;Faddegon B;Paganetti H;Schuemann J
通讯作者：
Schuemann J