Abstract：
Objective.To compare the accuracy with which different hadronic inelastic physics models across ten Geant4 Monte Carlo simulation toolkit versions can predict positron-emitting fragments produced along the beam path during carbon and oxygen ion therapy.Approach.Phantoms of polyethylene, gelatin, or poly(methyl methacrylate) were irradiated with monoenergetic carbon and oxygen ion beams. Post-irradiation, 4D PET images were acquired and parent11C,10C and15O radionuclides contributions in each voxel were determined from the extracted time activity curves. Next, the experimental configurations were simulated in Geant4 Monte Carlo versions 10.0 to 11.1, with three different fragmentation models-binary ion cascade (BIC), quantum molecular dynamics (QMD) and the Liege intranuclear cascade (INCL++) - 30 model-version combinations. Total positron annihilation and parent isotope production yields predicted by each simulation were compared between simulations and experiments using normalised mean squared error and Pearson cross-correlation coefficient. Finally, we compared the depth of the maximum positron annihilation yield and the distal point at which the positron yield decreases to 50% of peak between each model and the experimental results.Main results.Performance varied considerably across versions and models, with no one version/model combination providing the best prediction of all positron-emitting fragments in all evaluated target materials and irradiation conditions. BIC in Geant4 10.2 provided the best overall agreement with experimental results in the largest number of test cases. QMD consistently provided the best estimates of both the depth of peak positron yield (10.4 and 10.6) and the distal 50%-of-peak point (10.2), while BIC also performed well and INCL generally performed the worst across most Geant4 versions.Significance.The best predictions of the spatial distribution of positron annihilations and positron-emitting fragment production along the beam path during carbon and oxygen ion therapy was obtained using Geant4 10.2.p03 with BIC or QMD. These version/model combinations are recommended for future heavy ion therapy research.
摘要：
目的：比较跨十个Geant4蒙特卡罗模拟工具包版本的不同强子非弹性物理模型可以预测碳和氧离子治疗过程中沿束路径产生的正电子发射碎片的准确性。
材料与方法:聚乙烯幻影,明胶或聚（甲基丙烯酸甲酯）用单能碳和氧离子束辐照。辐照后,采集4DPET图像，从提取的时间活度曲线确定每个体素中10C和15O的放射性核素贡献。接下来,实验配置在Geant4蒙特卡罗版本10.0至11.1中进行了模拟，具有三种不同的碎裂模型-二元离子级联（BIC），量子分子动力学（QMD）和列日核内级联（INCL++）-30个模型版本的组合。使用归一化均方误差和Pearson互相关系数，在模拟和实验之间比较了每个模拟预测的总正电子an灭和母体同位素产量。最后,我们比较了每个模型和实验结果之间的最大正电子湮没产额的深度和正电子产额下降到峰值的50%的远点。
结果：不同版本和型号的性能差异很大，没有一个版本/模型组合可以提供所有评估的目标材料和辐照的所有正电子发射片段的最佳预测。Geant410.2中的BIC与最大数量的测试用例中的实验结果提供了最佳的总体一致性。QMD始终提供峰值正电子产量深度（10.4和10.6）和远端50％峰点（10.2）的最佳估计，而BIC也表现良好，INCL在大多数Geant4版本中表现最差。＆＃xD;＆＃xD;结论：发现碳和氧离子治疗过程中an灭产量和正电子发射碎片产生的最佳空间预测为10.2。p03与BIC或QMD。这些版本/模型组合被推荐用于未来的重离子疗法研究。
