Dedes G, Pinto M, Dauvergne D, Freud N, Krimmer J, Létang J M, Ray C, Testa E
Institut de Physique Nucléaire de Lyon, Université de Lyon, F-69003 Villeurbanne, France. IN2P3/CNRS, UMR 5822; Université de Lyon 1, F-69622 Villeurbanne, France.
Phys Med Biol. 2014 Apr 7;59(7):1747-72. doi: 10.1088/0031-9155/59/7/1747. Epub 2014 Mar 12.
Monte Carlo simulations are nowadays essential tools for a wide range of research topics in the field of radiotherapy. They also play an important role in the effort to develop a real-time monitoring system for quality assurance in proton and carbon ion therapy, by means of prompt-gamma detection. The internal theoretical nuclear models of Monte Carlo simulation toolkits are of decisive importance for the accurate description of neutral or charged particle emission, produced by nuclear interactions between beam particles and target nuclei. We assess the performance of Geant4 nuclear models in the context of prompt-gamma emission, comparing them with experimental data from proton and carbon ion beams. As has been shown in the past and further indicated in our study, the prompt-gamma yields are consistently overestimated by Geant4 by a factor of about 100% to 200% over an energy range from 80 to 310 MeV/u for the case of (12)C, and to a lesser extent for 160 MeV protons. Furthermore, we focus on the quantum molecular dynamics (QMD) modeling of ion-ion collisions, in order to optimize its description of light nuclei, which are abundant in the human body and mainly anticipated in hadrontherapy applications. The optimization has been performed by benchmarking QMD free parameters with well established nuclear properties. In addition, we study the effect of this optimization on charged particle emission. With the usage of the proposed parameter values, discrepancies reduce to less than 70%, with the highest values being attributed to the nucleon-ion induced prompt-gammas. This conclusion, also confirmed by the disagreement we observe in the case of proton beams, indicates the need for further investigation on nuclear models which describe proton and neutron induced nuclear reactions.
如今，蒙特卡罗模拟是放射治疗领域广泛研究课题的重要工具。它们在通过瞬发伽马探测开发质子和碳离子治疗质量保证实时监测系统的努力中也发挥着重要作用。蒙特卡罗模拟工具包的内部理论核模型对于准确描述束流粒子与靶核之间核相互作用产生的中性或带电粒子发射至关重要。我们在瞬发伽马发射的背景下评估了Geant4核模型的性能，并将其与质子和碳离子束的实验数据进行了比较。正如过去所表明的以及我们的研究所进一步指出的，对于(12)C的情况，在80至310 MeV/u的能量范围内，Geant4始终将瞬发伽马产额高估约100%至200%，对于160 MeV质子的情况高估程度较小。此外，我们专注于离子 - 离子碰撞的量子分子动力学(QMD)建模，以优化其对轻核的描述，轻核在人体中大量存在，并且主要预期用于强子治疗应用。通过用已确定的核性质对QMD自由参数进行基准测试来进行优化。此外，我们研究了这种优化对带电粒子发射的影响。使用建议的参数值后，差异减少到小于70%，最高值归因于核子 - 离子诱导的瞬发伽马。我们在质子束情况下观察到的分歧也证实了这一结论，这表明需要对描述质子和中子诱导核反应的核模型进行进一步研究。
