Affiliations: Institute of Biomedical Engineering, Chinese Academy
of Medical Sciences & Peking Union Medical College, Tianjin, China | Institute of Biomedical and Health Engineering,
Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences,
China
Note: [] Corresponding author: Tao Yin, Institute of Biomedical
Engineering, 7# Keyan Dong Road, Nankai District, Tianjin, 300192, China.
Tel.: +86 22 87891982; Fax: +86 22 87892951; E-mail: bme500@163.com
Abstract: Repetitive Transcranial magnetic stimulation (TMS) is a relatively
new technique, which is non-invasive and painless used to stimulate the central
and peripheral neural tissues. The principle is generating time-varying
magnetic fields to stimulate the cerebral cortex neuron and inducing eddy
current inside the tissues. Many researches study on the distributing of
magnetic field and electric field induced inside the human brain, whereas the
static electric field was neglected roughly in many studies. In this paper, a
five-sphere model is established to simulate the human head used in rTMS.
According to the different dielectric properties of the head tissues, the
Laplace equation of static electric field is deduced by both of Gauss theorem
and current's continuity principle. Boundary conditions used in different
interface between two adjacent layers in the five-sphere model is proposed in
this paper. Simulating study is conducted to calculate the distribution of the
electric field in the model. Simulating results suggest that the model is
useful to get the parameters of the most focus coil. Therefore this study could
be potential to promote the development of rTMS stimulator.
Keywords: rTMS, laplace's equation, boundary condition, finite element method, five-sphere model
