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题名	头部组织电导率分布对等效偶极子定位影响的研究; 头部组织电导率分布对等效偶极子定位影响的研究
作者	1杨旭,电工研究所
学位类别	硕士
答辩日期	2005
授予单位	中国科学院电工研究所
导师	1宋涛,电工研究所
关键词	脑电逆问题 偶极子定位 镜像法 序列二次规划 阻抗断层成像 EEG-IP Dipole Localization Mirror Method SQP EIT
其他题名	头部组织电导率分布对等效偶极子定位影响的研究
学位专业	电工理论与新技术
中文摘要	等效偶极子定位是广泛用于脑电逆问题研究的脑电发生源定位方法，脑电源定位在大脑高级功能研究、认知学研究和脑部疾病探测等领域具有的独特优势。本文主要通过脑电逆问题的仿真计算，研究了头部组织电导率分布与等效偶极子定位之间的敏感关系，并对实时探测电导率分布的方法进行了初步的探讨。本文在总结现有头模型建模方法的基础上，依据实际存在的头部组织电导率不均匀分布的情况建立了四层偏心球模型。利用准静态场线性叠加原理、对偶原理、镜像法和空间旋转变换，从传统的三层同心球模型解析解出发推导出四层偏心球镜像法解析解。并利用三维有限元计算软件进行对比验证其有效性。通过设定合理初值选择机制和约束条件，运用序列二次规划的方法进行逆问题迭代寻优，完成等效偶极子的定位运算。在此基础上通过仿真手段充分研究了如下两个问题：1、偏心球局部区域对等效偶极子定位产生的影响2、颅骨电导率的变化对等效偶极子定位产生的影响仿真结果证明头部组织电导率分布对等效偶极子定位影响显著。因此准确获得头部组织的电导率分布的几何信息及真实数值是提高定位精度的必要的条件与基础。为此搭建了完整的阻抗断层成像系统，成功地获得物理模型电导率分布图像，并进一步讨论了用于真实头部组织电导率探测的可行性与改进建议。以上计算推导和仿真实验的结果说明头部电导率分布对等效偶极子定位影响显著，阻抗断层成像和脑电逆问题的融合技术将会大大促进脑电逆问题和大脑高级功能的研究。 Equivalent dipole localization is a brain electrical source localization method widely used in electroencephalogram inverse problem (EEG BP) research. EEG IP has unique advantages in brain fimction research, cognition research and brain disease detection. This paper discussed the sensitivity relationship between electrical conductivity distribution and equivalent dipole localization by simulation of EEG IP.On the basis of current construction methods of head models, four-layer sphere model was constructed in this paper according to asymmetry prosperities of brain tissues. Using linearity adding theory, spouse theory, mirror method and space rotation transform, the analysis solution comes from widely used three-layer sphere model. The result was verified by calculation with FEM software.Given reasonable initial value and restrict condition, equivalent dipole localization was worked out by using Sequential Quadratic Programming (SQP). Based on the simulation method above, two propositions were studied as following:1. The respondence of equivalent dipole localization when the eccentric sphere with high electrical conductivity exists.2. The influence of skull electrical conductivity on equivalent dipole localization. The result proves that electrical conductivity distribution of brain tissues hassignificent influence on equivalent dipole localization. Consequently it is the foundation of improving localization precision to obtain the correct electrical conductivity and geometry information of brain tissue. Here we built up an electrical impedance tomography (EIT) system, and the images of model testing were acquired successfully, which proves the feasibility of application. Furthemore, advices of next improvement of applications on real brain tissue are also discussed.On the basis of calculation and simulation above, the result shows distribution of brain electrical conductivity has significent influence on equivalent dipole localization. Advanced brain function research will be in the nature of being promoted greatly by integrated technique of EEG IP and EIT.
语种	中文
公开日期	2010-10-18
页码	80
内容类型	学位论文
源URL	[http://ir.iee.ac.cn/handle/311042/7371]
专题	电工研究所_其他部门_其他部门_硕士学位论文
推荐引用方式 GB/T 7714	1杨旭,电工研究所. 头部组织电导率分布对等效偶极子定位影响的研究, 头部组织电导率分布对等效偶极子定位影响的研究[D]. 中国科学院电工研究所. 2005.

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