Simulations of low-frequency electromagnetic fields in the human body

• Main Author: Barchanski, Andreas
• Format: Others
• Language: English; en
• Published: 2007
• Online Access: https://tuprints.ulb.tu-darmstadt.de/888/1/promotion_barchanski.pdf; Barchanski, Andreas <http://tuprints.ulb.tu-darmstadt.de/view/person/Barchanski=3AAndreas=3A=3A.html> (2007): Simulations of low-frequency electromagnetic fields in the human body.Darmstadt, Technische Universität, [Online-Edition: http://elib.tu-darmstadt.de/diss/000888 <http://elib.tu-darmstadt.de/diss/000888> <official_url>],[Ph.D. Thesis]

In the presented thesis, the interaction of low-frequency electromagnetic fields with the human body is analysed using simulation techniques. The three major areas of the performed analysis are: a) The development of algorithms for the efficient calculation of low-frequency, electromagnetic fields in the human body. b) A quantitative estimation of the impact of applied approximations. c) The comparison of measurements and simulations. In the first area, a sub-gridding approach for a local grid refinement based on Lagrange multipliers is presented. Furthermore, a two-step algorithm for the efficient calculation of induced currents, originating from an exposure of the body to a time-varying magnetic field is proposed. Because this algorithm was implemented on a parallel architecture, a section of the thesis is dedicated to the performance of iterative solvers for the solution of linear systems of equations on multiple processors. In the second research area, the impact of the following modelling details are analysed: The neglect of the displacement current, the shielding effect of the induced currents and the impact of the conductivity dispersion for transient pulses during magnetic brain stimulation. For the comparison of simulations and measurements two scenarios are used. The first is the comparison of the body’s calculated and measured impedance. The second comparison is based on a mapping study of the motor cortex by means of a transcranial magnetic stimulation treatment.