Ansys Brain-based Eit Forward Problem

Brain science is an important subject in the field of life science in the 21st century. The feature of electrical impedance in the brain's inner tissue is the foundation of research on kinds of electromagnetic activities and analysis of pathology in inner brain, and it is also an important and difficult problem in brain science research. The Electrical Impedance Tomography (EIT) is an advanced calculated tomography technology. The EIT is such a technology carried as follows: we put current or voltage on the surface of organism according to electric parameters of different tissue in organism's body to reconstruct the distribution of every electric parameters in different tissues and then we can obtain the images of the organic inner tissues' correlated information by the proceed above. For the abundant physiological and pathological information it takes the technology has become a hot research on medical tomography. The EIT has great potential values in clinical medicine because it is not only safe, cheap, woundless and convenient, but very useful to check, prevent and cure illnesses for it can check out functional changes of a tissue or organ ahead of its structural changes in time.There are researches on three aspects in this paper:1. Research on two-dimension forward problem: Firstly we can obtain electric field's equation in low frequency according to five presumptions. This equation is known as EIT's controlling equation—laplace equation. Since Laplace equation is an elliptical partial differential equations whose solutions exist in radial symmetry simple model, we need to obtain the solutions by Finite Element Method. In this method, we can get two-dimension EIT's finite element methods equation group by means of variational methods in theory. Secondly if we want to get the solution from this equation in the software of ANSYS(a large-scale finite element methods' analytical software: analysis system), i.e. EIT simulation experiment, building head model suitable for this experiment is needed. Referring to the Stok model proposed in 1986, we build well-proportioned circle model in two-dimension plate and circles with one heart model with four layers. .Corresponding to theory, We adopt free gridding plot, regarding triangle as fundamental unit in dissection. And the number of the analytical layers that we judge from its error analytical draft is 12, then ,these two models could be loaded and solved respectively. My paper adopts copper spot electrode model by analyzing categories of drive model and electrode model when I load ,and I obtain well-proportioned and four-layered circle with one heart model's boundary electrode voltage images under certain frequency in two-dimension EIT forward problem. 2. Research on three-dimension EIT forward problem: EIT is a special electric field, whose mathematic model is equivalent to Laplace equation, whenever in two dimensions or three dimensions..Three-dimension problem is based on the two-dimension problem, so we can get its finite element methods equation group according to variational methods. The head model built in ANSYS will be changed into well-proportioned sphere and four-layered spheres with one heart, taking tetrahedrons unit. Then, anatomic models can be obtained in different situations.3. Research on inverse problem: The solution of inverse problem is to get the conductance's distribution in medium if surface voltage distributions and boundary conditions are known to all. We build the mathematic model of EIT inverse problem and then analyze image reconstruction arithmetic, the core of EIT inverse problem. The methods of arithmetic can be divided into the static reconstruction arithmetic and the dynamic reconstruction arithmetic. Finally, we can conclude the facts that static tomography are too much more in calculation, less in antinoise ability but more exact in conductance distribution reconstruction of organism; and the facts that dynamic tomography are less in calculation, better in realization, faster in reconstruction and that it can be used in in-time dispose.