【作者】 武力；

【导师】 骆清铭；

【作者基本信息】 华中科技大学 ， 生物医学工程， 2008， 博士

【摘要】 近年来随着层析成像技术和计算机技术的迅速发展,开发准确而真实的生物体解剖模型已经成为可能,原有的许多非常重要的生物电离辐射效应的观点和结论都需要被重新审视和评估。与此同时,随着辐射防护和应用的研究发展,建立评价非人类物种电离辐射影响的框架等新的需求也开始出现。要对这些重要的新旧观点进行重新审视和评估,必须开发出新的、准确而真实的生物体解剖模型,并将其运用到辐射研究领域并获得新的数据。本文通过一套小动物成像系统获取了Sprague Dawley(SD)大鼠的高精度断层图像数据集,运用自动、半自动和手动方法对其进行分割,并基于其分割结果数据集构建了一个全新的、真实的、具有大鼠准确解剖结构信息的体素模型。本文运用MCNPX蒙特卡罗辐射模拟代码,模拟了在多种辐射条件(DV、VD、LLAT、RLAT、ISO)、多种辐射能级(0.01~100 MeV)下,多种外部辐射粒子(光子、电子)与大鼠组织器官之间的物理反应。通过设置具体辐射条件、物理模型和物理反应,本文首次基于大鼠体素模型计算获得了在外部粒子辐射条件下一套完整的大鼠组织器官的吸收剂量(Absorbed Dose)和大鼠的有效剂量(Effective Dose),并以表格形式给出计算结果。本文搭建了一个可行的辐射剂量模拟计算平台,通过该计算平台可以模拟计算出其它小动物组织器官在给定辐射条件下获得的组织器官吸收剂量的分布。计算结果表明大鼠组织器官的体积、形状、位置和分布等解剖结构特征对其吸收剂量的分布有着重要的影响。外部辐射条件,如粒子类型、辐射方向、辐射能量也影响着大鼠组织器官的吸收剂量的分布。研究证明通过将生物体准确的解剖模型和计算机模拟计算相结合的方法,为获得外部粒子辐射对典型小动物的影响和其辐射吸收剂量分布信息提供了一种有效的手段。这些数据填补了目前非人类物种辐射计量数据集的空白,也为研究生物体解剖结构对放射剂量分布的影响提供了数据基础,从而为临床放疗规划、核医药、核辐射防护的动物试验设计提供精确量化参考。同时这些数据和结论可以推广到核辐射对其他小动物影响的研究上,也为建立一个非人类物种辐射效应评估框架提供了数据基础,对促进人类核防护和核医疗的进步有着重要意义。更多还原

【Abstract】 Recently, with the development of the tomograph imaging technologies and the computer technologies, a new anatomic voxel model of animal could be constructed to review and evaluated the old points made with the old mathmetic or simple models. Furthermore a framework for assessing the impact of ionising radiation on non-human spacies is advised to promoting radiation protection and utilization for human. For those reasons, the new anatomical models need be developed and be applied to acquire the new data in dosimety.In this paper, a Sprague Dawley (SD) rat anatomy atlas was acquired by a cryosection imaging system for small animal study. Through manual, self-automatic and automatic segmentation methods, an anatomically realistic rat model was developed based on the segmented images data of the rat.In this study, the procedures of the development of the voxel rat model for external photon and electron dosimetry and for broad range of incident energy (0.01~102 MeV ) under idealized irradiation geometries (DV、VD、LLAT、RLAT、ISO) have been detailed. A set of organ absorbed dose and effective dose results are computed and tabulated firstly.A simulated computation workstation is built, from which any animals organ dose distribution could be got.The results show that the organ dose distributions of the rat are distinctly influenced by the anatomical characteristics, including organ volume, shape, location, and orientation, and the radiation conditions, such as the particl type, the incident energy and the irradiation directions and so on.Research proves that the method combining the accurate anatomical model with the Monte Carlo code is an effective way to study the organs dose distributions and the reasons. The resulted data fill a data gas between exposure and dose and between dose and certain categories of effect for the no-human species. The data is also capable of offering exact quantitative references to animal experiments in clinic radiation therapy, radionuclide therapy and radiation protection. The experience and data concerning dose assessment from the rat model will be able to be deducted to small mammals, contribute to building the same framework for small mammals and improve the radiation therapy and protection for human ultimately.更多还原