Department of Health Physics and Diagnostic Sciences, School of Integrated Health Sciences, University of Nevada, Las Vegas, NV 89154, United States.
Department of Health Physics and Diagnostic Sciences, School of Integrated Health Sciences, University of Nevada, Las Vegas, NV 89154, United States.
Life Sci Space Res (Amst). 2024 May;41:29-42. doi: 10.1016/j.lssr.2024.01.003. Epub 2024 Jan 24.
During a human mission to Mars, astronauts would be continuously exposed to galactic cosmic rays (GCR) consisting of high energy protons and heavier ions coming from outside our solar system. Due to their high energy, GCR ions can penetrate spacecraft and space habitat structures, directly reaching human organs. Additionally, they generate secondary particles when interacting with shielding materials and human tissues. Baryon secondaries have been the focus of many previous studies, while meson and lepton secondaries have been considered to a much lesser extent. In this work, we focus on assessing the tissue-specific dose equivalents and the effective dose for males of secondary mesons and leptons for the interplanetary cruise phase and the surface phase on Mars. We also provide the energy distribution of the secondary pions in each human organ since they are dominant compared to other mesons and leptons. For this calculation, the PHITS3.27 Monte Carlo simulation toolkit is used to compute the energy spectra of particles in organs in a realistic human phantom. Based on the simulation data, the dose equivalent has been estimated with radiation quality factors in ICRP Publication 60 and in the latest NASA Space Cancer Risk model (NSCR-2022). The effective dose is then assessed with the tissue weighting factors in ICRP Publication 103 and in the NSCR model, separately. The results indicate that the contribution of secondary mesons and leptons to the total effective dose is 6.1 %, 9.1 %, and 11.3 % with the NSCR model in interplanetary space behind 5, 20, and 50 g/cm aluminum shielding, respectively, with similar values using the ICRP model. The outcomes of this work lead to an improved understanding of the potential health risks induced by secondary particles for exploration missions to Mars and other destinations.
在人类火星任务中，宇航员将持续暴露于银河宇宙射线（GCR）中，这些射线由来自太阳系外的高能质子和重离子组成。由于其能量很高，GCR 离子可以穿透航天器和太空栖息地结构，直接到达人体器官。此外，当与屏蔽材料和人体组织相互作用时，它们会产生次级粒子。重子次级粒子一直是许多先前研究的重点，而介子和轻子次级粒子则被考虑得少得多。在这项工作中，我们专注于评估星际巡航阶段和火星表面阶段男性次级介子和轻子的组织特异性剂量当量和有效剂量。我们还提供了每个人体器官中次级π介子的能量分布，因为它们与其他介子和轻子相比占主导地位。对于这种计算，使用 PHITS3.27 蒙特卡罗模拟工具包来计算真实人体模型中器官中粒子的能谱。基于模拟数据，使用 ICRP 出版物 60 中的辐射品质因数和最新的 NASA 太空癌症风险模型（NSCR-2022）估算了剂量当量。然后，使用 ICRP 出版物 103 和 NSCR 模型中的组织权重因子分别评估了有效剂量。结果表明，在星际空间中，使用 NSCR 模型，在 5、20 和 50 g/cm 铝屏蔽后面，次级介子和轻子对总有效剂量的贡献分别为 6.1%、9.1%和 11.3%，使用 ICRP 模型时，其值相似。这项工作的结果导致对探索火星和其他目的地的任务中次级粒子引起的潜在健康风险有了更好的理解。
