Research On Magnetic Field Distribution Analysis Of Deep Transcranial Magnetic Stimulation

With the development of life, the mental illness has become the biggest threat tohuman life and the medical resources rather than infectious disease. Magneticstimulation could affect the brain dysfunction which is ma in character of mentalillness. Transcranial magnetic stimulation (TMS) is an effective method of curing themental illness with low strength and high accuracy. This paper proposes a newtherapeutic method—deep transcranial magnetic stimulation (DTMS) with charactersof non-invasively, weak magnetic field, and multiparameter adjustable based onprinciple of TMS.Firstly, this paper demonstrates the distribution of magnetic field under differenttypes and sizes of the coils, especially the TMS coils and DTMS double coils with thesame amplitude and direction of current. The magnetic flux density distributioncurves of the center line of coils were displayed. The paper also summarizes thefactors affecting induced field, including the size of coils, the conductivity of braintissue, the relative position between coil and brain tissue and so on.This paper comes up with the overall design scheme of DTMS magneticstimulation device, which including the design of the man-machine interactiveinterface, the design of coil related parameters and the design of waveform control.According to the intensity of stimulation, this paper displays the bridge circuit whichcontrol different input waveform and Buck-Boost chopper circuit. In the last part, thispaper proved influence of DTMS magnetic stimulation for nervous system throughthe animal and clinical experiments.In order to study the active mechanism of DTMS on the brain, this article uses thefinite element analysis method for the calculation of electromagnetic field, and givesthe relationship between parameters of magnetic field and brain. We build the headmodel with ANSYS software, analyze the influence of the distance between the modeland coils and the conductivity of gray boundary. It is found that the conductivity ofgray boundary is the important factor affecting the induced field, which also affectssome brain function.The research results provide the theoretical basis for detecting and treating mentalillness, and depicting the difference of neural electrical activity among cortex function areas.