基于磁感应生物阻抗成像的电磁场正问题研究

发布时间：2018-11-08 09:17

【摘要】：磁感应断层成像（MIT）是一种新兴的生物组织电特性成像方法，，该方法通过检测涡流信号提取成像区域的电特性信息，并用图像重建方法获取图像。MIT检测灵敏度直接影响到成像质量和速度，而MIT模型参数又与检测灵敏度密切相关。其中电磁场正问题作为其系统设计和重建方法的基础成为MIT研究中的重要部分。本文结合电磁感应原理、涡流检测理论、场—路耦合有限元方法研究MIT电磁场正问题。首先，根据人体头部的结构，建立了含有病变和无病变的人体头部模型作为MIT的检测对象。并建立激励源（激励线圈）模型，研究在被检测体中的磁场分布，获得MIT系统模型的几何参数范围。其次，采用场—路耦合有限元法，在改变激励、检测线圈几何尺寸（半径、线径、匝数）、激励频率、激励电压、激励线圈与被检测体距离条件下，分别在包含有病变组织和无病变组织两种情况下进行仿真计算，研究被检测体轴向磁感应强度变化及检测线圈中的感应电压。通过对轴向磁感应强度变化梯度和检测线圈感应电压的幅值和相位差，给出提高MIT检测灵敏度的激励线圈相关参数。另外，含有磁芯及检测线圈与激励线圈同侧、异侧两种空间位置情况下，分析其对检测灵敏度的影响。最后，通过仿真实验研究了病变组织空间位置、电导率大小、半径大小对轴向磁感应强度、感应电压幅值、感应电压相位的影响。结果表明，本文所设计的仿真算法与模型能够模拟简单的实际测量情况，对MIT系统设计具有重要的指导意义。
[Abstract]:Magnetic Induction Tomography (MIT) is a new electrical characteristic imaging method for biological tissue. The MIT detection sensitivity directly affects the imaging quality and speed, and the parameters of the MIT model are closely related to the detection sensitivity. Electromagnetic forward problem, as the basis of system design and reconstruction, has become an important part of MIT research. In this paper, the forward problem of MIT electromagnetic field is studied by combining the electromagnetic induction principle, eddy current detection theory and field-circuit coupled finite element method. Firstly, according to the structure of human head, the human head model with or without pathological changes was established as the detection object of MIT. The excitation source (excitation coil) model is established to study the magnetic field distribution in the detected body and the geometric parameter range of the MIT system model is obtained. Secondly, the field-circuit coupling finite element method is used under the condition of changing the geometry dimension (radius, line diameter, turn number), exciting frequency, exciting voltage, and the distance between the exciting coil and the detected body. The axial magnetic induction intensity of the detected body and the inductive voltage in the detecting coil were studied by simulation under the condition of both diseased tissue and non-diseased tissue. Based on the gradient of the axial magnetic induction intensity and the amplitude and phase difference of the inductive voltage of the detecting coil, the related parameters of the excitation coil to improve the detection sensitivity of the MIT are given. In addition, the influence of the magnetic core and the detecting coil on the detection sensitivity is analyzed under the condition of the same side of the detecting coil and the different side of the coil. Finally, the effects of the location, conductivity and radius of the lesion on the axial magnetic induction intensity, the amplitude of inductive voltage and the phase of inductive voltage are studied by simulation experiments. The results show that the simulation algorithm and model designed in this paper can simulate simple actual measurement situation and have important guiding significance for the design of MIT system.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R310

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