Geant4用于预测离子束治疗中正电子发射碎片产额与分布的定量评估
A quantitative assessment of Geant4 for predicting the yield and distribution of positron-emitting fragments in ion beam therapy
AI总结：
本研究评估10个版本Geant4的三种碎裂模型对碳氧离子治疗中正电子发射碎片的预测能力，发现10.2.p03版搭配BIC或QMD模型表现最优，为后续重离子治疗研究提供模拟工具选择参考。
摘要：
目的：比较Geant4蒙特卡罗模拟工具包10个版本中不同强子非弹性物理模型，对碳离子和氧离子治疗期间沿束流路径产生的正电子发射碎片的预测准确性。\n材料与方法：使用单能碳离子和氧离子束照射聚乙烯、明胶或聚甲基丙烯酸甲酯体模。照射后采集4D PET图像，并从提取的时间活度曲线中确定每个体素中母体核素¹¹C、¹⁰C和¹⁵O的贡献。采用Geant4 10至11.1版本开展实验模拟，涉及三种碎裂模型：二元离子级联（BIC）、量子分子动力学（QMD）和列日内核级联（INCL++），共30种组合。使用归一化均方误差和皮尔逊互相关系数，比较模拟与实验之间的总/母体同位素正电子湮没产额，同时比较了最大产额深度和远端50%峰位深度。\n结果：不同版本和模型的性能差异显著，没有一种模型能最优预测所有正电子发射碎片。Geant4 10.2版本中的BIC在最多测试案例中与实验结果整体一致性最佳。QMD对正电子产额峰深度（10.4和10.6）以及远端50%峰位点（10.2）的估计始终最优，BIC表现也较好，而在大多数Geant4版本中INCL整体表现最差。\n结论：对于碳和氧离子治疗期间的湮没产额与正电子发射碎片产生，空间预测效果最佳的是搭载BIC或QMD的10.2.p03版本。推荐这些版本/模型组合用于未来的重离子治疗研究。
英文摘要：
Purpose: 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. Materials and Methods: 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 parent $^{11}$C, $^{10}$C and $^{15}$O radionuclides contributions in each voxel were determined from the extracted time activity curves. Experiments were simulated in Geant4 Monte Carlo versions 10-11.1, with three different fragmentation models: binary ion cascade (BIC), quantum molecular dynamics (QMD) and the Liege intranuclear cascade (INCL++) - 30 combinations. Total/parent isotope positron annihilation yields were compared between simulations and experiments using normalised mean squared error and Pearson cross-correlation coefficient. Depth of maximum/distal 50\% peak position yield were also compared. Results: Performance varied considerably across versions and models, with no one best predicting all positron-emitting fragments. 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. Conclusions: Best spatial prediction of annihilation yield and positron-emitting fragment production during carbon and oxygen ion therapy was found to be 10.2.p03 with BIC or QMD. These version/model combinations are recommended for future heavy ion therapy research.
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