【作者】 倪婕；

【导师】 孙亮； Lembit Sihver；

【作者基本信息】 苏州大学 ， 生物医学工程， 2013， 硕士

【摘要】 人体辐射健康危害取决于辐射能量在人体的沉积分布及后续复杂的生物学过程。依据辐射损伤机制经典学说--靶学说，DNA分子是辐射损伤最重要的靶，辐射能量在其内的沉积特点对辐射生物效应的解释具有重要意义。考虑到细胞是人体的基本功能单元且DNA分子受损后的各种生物学响应均与细胞环境有关，因此，在细胞水平开展辐射剂量学研究对辐射损伤机制的深入了解及其在辐射防护和放射治疗等方面的实用化具有重要意义。目的：单细胞模型是辐射能量在细胞水平上沉积特点和规律获取的重要平台。本文旨在得到合理可行的单细胞模型建立方法，并据此建立更加接近真实细胞的Monte Carlo计算模型。材料与方法：采用具有肿瘤细胞代表性的人口腔上皮癌细胞作为研究对象，基于生物学手段和计算机图形技术摸索模型的建立方法，并结合GEANT4蒙特卡罗模拟软件进行辐射照射下细胞内能量沉积规律的获取。结果：成功建立了单细胞模型，并针对该模型进行了适用性和实用性的测试。在此基础上进行了剂量学计算，结果表明，在综合考虑计算时间和计算精度的情况下对7组数据进行分析，最终将图像分辨率设为0.3-0.4μm范围内，用200个3MeV的α粒子对单细胞模型进行照射，得到细胞核内单个粒子击中细胞的平均比能均值为0.209Gy；细胞质内单个粒子击中细胞的平均比能均值为0.044Gy。本文得到的计算结果与已公布数据吻合，建立单细胞体素模型的方法切实可行且通用性强；细胞核的密度与细胞形态对模型计算结果有重要影响，建立不同细胞系的细胞库是对于放射生物学的研究非常有必要的。更多还原

【Abstract】 The radiation damage to human are highly dependent on the energy distributionand a series biological and chemical process in body. Once DNA was established as themolecule that encodes the genetic instructions used in the development and functioningof all known living organism and many viruses, it was suggested as the critical target.This was the start of the target theory, which states that there is a critical point in the cellthat must be hit in order to induce cell death, and radiation damage outside of this targetshould not cause cell death. For many years it has been thought that DNA is the criticaltarget in a cell exposed to radiation, and although much evidence has accumulated tosuggest that there are other targets within the cell that can lead to significant damage,DNA is still of critical importance. Cell is the basic unit of human body and the innerenvironment of cell has influences on radiation effect. Thus, it’s necessary to study theradiation mechanism on cell level.This paper is to establish a method to modeling a single cell, which can be appliedin Monte Carlo simulation.Materials and Methods: KB cell, as being typically tumor cells, is chosen as ourresearch object. After the cells are cultured and stained, images are taken by confocalmicroscopy. Data is extracted from images and imported into Geant4for modeling.Mean specific energy in nucleus and cytoplasm is calculated separately.Results:7single cells are analyzed. Considering calculating time and accuracy,the resolution scales are set in the range of0.3-0.4μm and the number of αparticle with3MeV energy is set to be200.The calculating results shows that by a single particle hit,the mean specific energy in nucleus is0.209Gy and that in cytoplasm is0.044Gy.Conclusion: the modeling method we developed is practical and universal, inwhich the density of nucleus and cell shape effect the calculating results a lot. This study is based on open-source software and the results are in agreement withpublished data.更多还原