Method for Electromagnetic Thermal Dosimetry of the Human Brain Exposed to High Frequency Fields

Mario Cvetković
January 2013
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Abstract

The dissertation describes in detail the development of the electromagnetic and thermal model of the human brain. The electromagnetic model based on integral equations was derived using the equivalence theorem with the application of boundary conditions for the case of a dielectric body of arbitrary shape with losses included. The thermal model of the brain is based on the form of the Pennes equation of heat transfer in biological tissue extended by an additional term representing the absorbed electromagnetic energy density. In addition to detailed guidelines for calculating various surface integrals that occur in the electromagnetic model, an adapted analytical-numerical technique for singularity extraction is presented, useful for correcting instabilities that occur when using a purely numerical approach. The developed electromagnetic-thermal model was applied to internal dosimetry of the human brain to determine the absorbed electromagnetic energy and the consequent increase in temperature due to exposure to an incident plane high-frequency electromagnetic wave. Furthermore, the developed model was also applied to rigorous modeling of the transcranial magnetic stimulation technique, where, by including radiation effects, a more exact physical description of the problem is obtained compared to existing models. Finally, the sensitivity of the results to changes in various electrical and thermal tissue parameters used in the model was examined, and a comparison of internal brain dosimetry in an adult and a ten- and five-year-old child was provided, taking into account age-dependent tissue parameters.

Type
Thesis
Electromagnetic Model Thermal Model Internal Dosimetry Integral Equations Human Brain Transcranial Magnetic Stimulation High Frequency Fields Computational Electromagnetism Numerical Methods
Mario Cvetković
Mario Cvetković
Associate Professor | Department of Electrical Engineering Fundamentals

Associate professor at FESB in Split, with a research focus on numerical modeling including finite element and moment methods, computational bioelectromagnetics and heat transfer related phenomena. He is involved in IEEE’s ICES Technical Committee 95, various international projects and is committed to advancing both knowledge and practical applications in electromagnetic safety and biomedical engineering.