Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia.
iThemba Laboratory for Accelerator Based Sciences, Cape Town, South Africa.
Phys Med. 2021 Oct;90:176-187. doi: 10.1016/j.ejmp.2021.09.008. Epub 2021 Oct 20.
In this study, Monte Carlo codes, Geant4 and MCNP6, were used to characterize the fast neutron therapeutic beam produced at iThemba LABS in South Africa. Experimental and simulation results were compared using the latest generation of Silicon on Insulator (SOI) microdosimeters from the Centre for Medical Radiation Physics (CMRP). Geant4 and MCNP6 were able to successfully model the neutron gantry and simulate the expected neutron energy spectrum produced from the reaction by protons bombarding a Be target. The neutron beam was simulated in a water phantom and its characteristics recorded by the silicon microdosimeters; bare and covered by a B enriched boron carbide converter, at different positions. The microdosimetric quantities calculated using Geant4 and MCNP6 are in agreement with experimental measurements. The thermal neutron sensitivity and production of B capture products in the p+ boron-implanted dopant regions of the Bridge microdosimeter is investigated. The obtained results are useful for the future development of dedicated SOI microdosimeters for Boron Neutron Capture Therapy (BNCT). This paper provides a benchmark comparison of Geant4 and MCNP6 capabilities in the context of further applications of these codes for neutron microdosimetry.
在这项研究中，我们使用蒙特卡罗代码、Geant4 和 MCNP6 来描述南非 iThemba LABS 产生的快中子治疗束。我们使用来自医疗辐射物理中心（CMRP）的最新一代绝缘体上硅（SOI）微剂量计对实验和模拟结果进行了比较。Geant4 和 MCNP6 能够成功地对中子龙门架进行建模，并模拟出由质子轰击 Be 靶产生的预期中子能谱。我们在水模体中模拟了中子束，并通过硅微剂量计记录了其特性；在不同位置，微剂量计暴露于中子束下或被硼碳化物富硼转换器覆盖。使用 Geant4 和 MCNP6 计算出的微剂量学参数与实验测量值一致。我们研究了 Bridge 微剂量计中 p+硼注入掺杂区的热中子灵敏度和 B 俘获产物的产生。获得的结果对未来专门用于硼中子俘获治疗（BNCT）的 SOI 微剂量计的开发具有重要意义。本文提供了 Geant4 和 MCNP6 能力的基准比较，以便在进一步应用这些代码进行中子微剂量学方面进行参考。
