头部电阻抗成像正问题的解析解研究

建立头颅的球型仿真模型.用头皮、颅骨、脑脊髓和脑组织四层同心球结构模拟头颅.对各层组织采用复数电导率,用分离变量法分析头颅球模型在最外层(头皮层)表面施加点电流激励的情况下,内层的电位分布.根据电位分布的表达式,绘制出颅内的电位等位线图.分析电流注入角度对电位分布的影响.仿真结果表明,当颅内脑组织电导率变化时,头皮表面电位的实部变化明显大于虚部,激励电流频率变化对头皮表面电位虚部的影响较为明显.研究结果可用于分析头部电阻抗成像问题.

Analytical Solution of Forward Problem in Brain Electrical Impedance Tomography

A 4-layer sphere model of human head is built.Layers from outside to inside represent scalp,skull,CFS and brain,respectively.The point current source placed on the outmost layer is regarded as boundary condition. A method of separation of variables is used to solve the equations.Potential distributions with different injecting angles are shown.We simulate conductivity distribution of brain tissue,and plot real and imaginary potentials at nine points on the outmost layer.As conductivity of brain tissue changes,the real potentials vary greatly than the imaginary parts.Frequency characteristic is simulated,and the result shows that the imaginary potentials on the outmost layer is influenced mostly by frequency.These can be used in analyzing head EIT problems and improving the Back-projection Algorithm.