基于数字人体的程式化模型和曲面模型构建及外辐射剂量研究

发布时间：2018-12-31 07:52

【摘要】：电离辐射是地球和宇宙空间自然环境的固有特征之一,与人类健康关系密切。衡量辐射危害及其严重程度的重要指标是辐射剂量。为了更有效地保护人类自身和所处环境,需要在生产、医疗、科研等电离辐射应用中,有针对性地评估受照对象的具体剂量,以掌握可能存在的辐射效应及其潜在危害,并通过客观指标指导辐射防护计划制定和屏蔽设备设计。在运用蒙特卡罗方法进行电离辐射剂量计算时,人体可计算模型至关重要。但现有各类人体模型中,基于中国人体解剖学特征的可计算模型尚未完善,不能完全满足各种实际应用需求,迫切需要进行各类可计算模型建模和辐射剂量计算,以实现人体辐射剂量的评估和防护研究。本文根据中国数字人体男性和女性体素模型,构建了准确的男性和女性程式化模型,其中,女性体素模型根据中国数字人女一号人体彩色截面图像建立。为进一步完善中国数字人体可计算辐射模型,加强人体辐射仿真模型的解剖学真实性和可变形性,基于已建立模型构建了人体曲面模型,详细阐述了构建过程。结合辐射剂量计算的需求,本文将中国数字人体可计算模型应用于光子、中子、质子辐照引起的全身各组织器官剂量的MCNP蒙特卡罗模拟计算,全身有效剂量评估及辐射屏蔽研究中。通过剂量对比,分析讨论了影响人体内部组织器官剂量的若干因素。针对中国女性航天员质子辐照剂量的评估问题,进行了在轨剂量的快速近似计算,对比了屏蔽前后的剂量差异,分析了其中的解剖学因素。主要研究结果和创新如下： (1)在中国数字人体程式化模型的构建中,由体素模型获取人体组织器官参数,误差在5%以内,相对于其他模型,差异处在较小水平。在中国数字人体曲面模型的构建中,保证了人体解剖结构的真实性、精确性和可变性。 (2)通过光子和中子照射下剂量的定量比较,本研究发现：光子照射下器官剂量的转换系数曲线具有明显的方向特征,与照射方向密切相关,不仅显示出了数值上的差异,器官剂量转换系数曲线的形状都有明显的不同。而在中子照射下,不同能级粒子的穿透力不同,会形成不同的沉积能量,器官吸收剂量在两个区域分别形成了平台期和上升期。 (3)通过中国女性航天员模型的质子剂量评估,本研究发现,质子的入射和能量沉积方式与光子和中子入射的情况存在着较大的差异。皮肤并不会对内部器官的吸收剂量产生大的影响,但使乳腺的布拉格峰向高能段移动约20MeV。在屏蔽条件下,辐射粒子在穿透材料的过程中能量损失增加,人体器官剂量会有所减少。在1.35g/cm2厚度屏蔽层的条件下,器官剂量平均降低了13.90%(9.00%到24.20%之间不等),皮肤剂量是一个例外,降低了52.20%。本研究中所建立的基于中国数字人体男一号和女一号的人体可计算辐射剂量模型,同时包含程式化模型,体素模型和曲面表面模型三类模型,完善了中国数字人体可计算模型,开发了一个辐射剂量计算和风险评估的可调模板。本文中提供的数据有助于改善现有中国人体剂量学数据集,夯实了可计算模型在辐射防护领域中的应用,对各类照射情况下的剂量计算,各种身体类型和体姿下的剂量研究,以及辐射剂量的准确估算和实时辐射防护,都有积极的推动作用。
[Abstract]:Ionizing radiation is one of the distinctive features of the natural environment of the earth and the cosmic space, and is closely related to human health. The important index to measure the radiation hazard and its severity is the radiation dose. in order to protect the human and the environment more effectively, it is necessary to evaluate the specific dose of the irradiated object in the application of ionizing radiation such as production, medical treatment, scientific research and the like to master possible radiation effects and potential hazards, and the design of the radiation protection plan and the design of the shielding equipment are guided through the objective index. In the calculation of the ionizing radiation dose by the Monte-Carlo method, the model of the human body can be calculated. However, in the present various human models, the computable model based on the Chinese human anatomy features is not perfect, can not completely meet the actual application requirements, and the models and radiation dose calculation of various kinds of calculable models are urgently needed to realize the evaluation and protection research of the radiation dose of the human body. In this paper, according to the model of Chinese digital human male and female body, an accurate model of male and female programming is constructed, in which the model of female body is built according to the color section image of Chinese digital human female No. 1. In order to further improve the Chinese digital human body, the radiation model can be calculated, the anatomical authenticity and the deformability of the human radiation simulation model are strengthened, the human curved surface model is constructed based on the established model, and the construction of the human body surface model is described in detail. Based on the requirements of the radiation dose calculation, this paper applies the Chinese digital human body computable model to the MCNP Monte Carlo simulation of the whole body tissue organ dose caused by photon, neutron and proton irradiation, and the whole-body effective dose assessment and the radiation shielding study. In this paper, a number of factors influencing the internal organ dose of human body were discussed by means of dose contrast. In order to evaluate the dose of the proton irradiation of Chinese women's astronaut, the rapid approximation of the dose of the rail was carried out, the difference of the dose before and after the shield was compared, and the anatomical reasons were analyzed. Main findings and findings The new method is as follows: (1) In the construction of the Chinese digital human body programming model, the body element model is used to obtain the organ parameters of the human body, the error is within 5%, In the construction of the Chinese digital human curved surface model, the authenticity and accuracy of the anatomy of the human body are ensured. (2) By means of the quantitative comparison of the dose under the irradiation of the photon and the neutron, the present study found that the conversion coefficient curve of the organ dose under the irradiation of the photon has a clear direction characteristic, which is closely related to the irradiation direction, not only is shown, the difference in values, the shape of the organ dose conversion coefficient curve, It is obvious that under the irradiation of the neutron, the penetrating power of different energy level particles is different, different deposition energy is formed, and the absorbed dose of the organ is formed in two regions respectively. The study found that the incident and energy deposition of the proton and the incident of the photon and the neutron were observed by the proton dose assessment of the Chinese female astronaut model. There is a large difference in the condition. The skin does not have a great effect on the absorbed dose of the internal organs, but the Bragg peak of the breast is given high energy In the shielding condition, the energy loss of the radiation particles in the process of penetrating the material is increased, and the human body The organ dose decreased. The mean organ dose was reduced by 13.90% (9.00% to 24.20%) under the condition of 1. 35g/ cm2 of the shielding layer, and the skin dose was an exception. The radiation dose model of the human body based on Chinese digital human male 1 and female 1, which is based on Chinese digital human body and female No. 1, is established in this study, and the three models of the programming model, the body element model and the surface model are also included, and the radiation dose model is improved. Chinese digital human body computable model, developed a radiation dosimeter The data provided in this paper can help to improve the existing data set of human dosimetry in China, and tamp the application of the computable model in the field of radiation protection. Dose studies in type and body posture, as well as accurate estimation of radiation dose and real-time radiation protection
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2012
【分类号】：R144.1

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