深度经颅磁刺激电磁场分布的分析研究

发布时间：2018-12-08 07:38

【摘要】：随着当今社会生活节奏的不断加快，，精神疾病代替传染病已经成为了威胁人类生命、消耗医药资源最大的疾病。精神疾病的主要体现是脑功能异常，而磁刺激可以影响脑功能。经颅磁刺激（TMS）是目前唯一能够无创式、精确定位治疗与探测脑功能的有效方法，但其机理尚不明确且存在定位困难、高强度等缺陷。在TMS基础上，本文提出一种无创性、低强度、弱磁场、多参数可调的深度经颅磁刺激（DTMS）并使用ANSYS有限元软件分析了其影响脑功能的机理。本文首先给出了不同类型、不同尺寸线圈产生的磁场分布图，然后详细分析了在大小、方向相同的电流作用下TMS圆线圈和DTMS双线圈的磁场分布图，给出了线圈中心点所在直线上的磁通密度分布曲线，并归纳总结了影响磁刺激感应磁场的因素，包括线圈尺寸、大脑内部组织的电导率、线圈与组织的相对位置。基于上述分析结果，本文提出了新的无创性磁刺激装置—DTMS磁刺激装置，并给出了该系统的总体设计方案，包括人际交互界面设计、线圈相关参数设计及控制电路设计。根据所需刺激强度的不同，本文对DTMS系统刺激波形进行了分析。通过动物和临床实验证明了DTMS磁刺激对神经系统的影响。为了研究DTMS对大脑的作用机制,本文采用有限元分析方法进行电磁场的计算，给出了磁场参数与大脑参数之间的关系；利用ANSYS有限元分析软件,建立了DTMS系统的模型，详细分析了线圈与头部之间的距离及灰质边界电导率发生变化时对DTMS感应磁场的影响，发现了灰质的边界电导率是影响DTMS感应磁场的重要因素，这也是影响某些脑功能的关键因素。本文的研究结果为DTMS探测和治疗精神疾病的机制，刻画正常和精神疾病状态下某个皮层功能区域内以及区域之间的神经电活动特性差异提供了理论基础。
[Abstract]:With the increasing pace of social life, mental illness has become the most important disease that threatens human life and consumes medical resources. The main manifestation of mental illness is abnormal brain function, and magnetic stimulation can affect brain function. Transcranial magnetic stimulation (TMS) is the only effective method to treat and detect brain function accurately and noninvasively, but its mechanism is not clear and has defects such as difficult location and high intensity. On the basis of TMS, a non-invasive, low-intensity, weak magnetic field, multi-parameter adjustable depth transcranial magnetic stimulation (DTMS) is proposed and the mechanism of its influence on brain function is analyzed by ANSYS finite element software. In this paper, the magnetic field distribution diagrams of different types and sizes of coils are given, and then the magnetic field distributions of TMS circular coils and DTMS double coils under the same current size and direction are analyzed in detail. The distribution curve of magnetic flux density on the line at the center point of the coil is given, and the factors affecting the magnetic field induced by magnetic stimulation are summarized, including the size of the coil, the conductivity of the inner brain tissue, and the relative position of the coil and the tissue. Based on the above analysis results, a new non-invasive magnetic stimulation device, DTMS magnetic stimulation device, is proposed in this paper, and the overall design scheme of the system is given, including the design of the interpersonal interface, the design of the coil parameters and the design of the control circuit. According to the different intensity of DTMS system, the stimulation waveform of DTMS system is analyzed in this paper. The effect of DTMS magnetic stimulation on nervous system has been proved by animal and clinical experiments. In order to study the action mechanism of DTMS on the brain, the finite element analysis method is used to calculate the electromagnetic field, and the relationship between the magnetic field parameters and the brain parameters is given. The model of DTMS system is established by using ANSYS finite element analysis software. The influence of the distance between coil and head and the conductivity of gray matter boundary on the inductive magnetic field of DTMS is analyzed in detail. It is found that the boundary conductivity of gray matter is an important factor affecting the induced magnetic field of DTMS, which is also the key factor affecting some brain functions. The results of this study provide a theoretical basis for the mechanism of DTMS detection and treatment of mental disorders and the characterization of the differences in the characteristics of neural electrical activity within and between regions of a cortical functional region under normal and psychiatric conditions.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.6

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