Numerical analysis of interactions between electromagnetic fields and human bodies
Numerous electronic devices operate in the close vicinity of human bodies. Such proximity can lead to a fraction of electromagnetic energies being deposited into human bodies. If the power absorbed is sufficiently large, it may lead to tissue damage. Consequently, interactions of electromagnetic fields with human subjects have been a subject of scientific interest and public concern. On the other hand, some electronic devices taking advantage of such interactions have been developed and applied as effective medical treatments. The research presented in this thesis aims at providing numerical approaches to study the interactions of electromagnetic fields, ranging from low frequency to radio frequency (RF), with human bodies.
Realistic human subject models are necessary in numerical investigations. Nine pregnant woman models, based on magnetic resonance scans, were developed for electromagnetic and thermal analyses. In addition, a realistic male model was also used for numerical analyses.
A novel transcranial magnetic stimulation (TMS) structure is proposed to overcome the limitations of conventional TMS coils. This proposed structure is capable of achieving reconfigurable, multi-channel, and time-sequence magnetic stimulations. The validation of this novel TMS system was verified by numerical simulations and experiments.
The induced current densities and induced electric fields within pregnant woman models exposed to walk-through metal detector (WTMD) emissions were investigated. Through comparisons to current safety limits, it is shown that internal tissues might experience potentially hazard effects due to external magnetic fields.
The electromagnetic and thermal simulations were combined to study the heating effects of strong RF fields on internal tissues within pregnant woman models exposed to magnetic resonance imaging (MRI) RF coil radiations. Simulation results demonstrated that fetus tissue might have higher specific absorption rate and resultant temperature rise than recommended safety limits.
The safety of metallic implants within MRI scan was investigated by performing numerical modeling. The heating effects, caused by the interactions between metallic implants and electromagnetic fields from the MRI coil, were significant.