Forward Problem Solution of Mgnetic Fields Outside of Human Head Using New Four Layer Eccentric Spherical Model

In this paper, the magnetic field outside human head was obtained by method of forward problem solution and using new four layer eccentric spherical conductor model for human head. The use of numerical methods for human head has little accuracy due to dimensions of human head and low frequency of brain waves. Using cocentric models due to the difference in the actual geometric shape of different layers of human head and cocentric spheres causes errors in estimating source location. The three layer model can cause errors due to ignoring difference in conductivity between the brain and the cerebrospinal fluid around the brain. Therefore, the results related to eccentric four layer spherical model in this paper are more accurate than the results related to three layer spherical model. The spherical model has isotropic layers, that is, the electrical conductivity coefficients of each layer are the same at all points of that layer. The equations were obtained analytically using a dipole as a source. According to our results, it was observed that the magnetic field graph of the new model has little changes compared with to other models.