Uncertainty in computational RF dosimetry

Radio-frequency (RF) electromagnetic field dosimetry studies the absorption of electromagnetic energy inside the human body. The absorbed energy is measured in terms of the specific absorption rate (SAR), which is linked to the possible adverse thermal effects of the exposure to RF electromagnetic fields. With advances in computational power and accurate numerical models of the human anatomy, computational methods have gained an increasingly significant role in RF dosimetry in recent years. Nowadays, the finite-difference time-domain (FDTD) method is the most widely used numerical technique in computational RF dosimetry. Computational analysis of the SAR features many modelling and approximation phases that may introduce error and uncertainty. The emphasis of this thesis is to study how reliably the SAR can be assessed by the FDTD method, and how various modelling choices affect the accuracy of the simulated results. In addition to the SAR, also the temperature rise due to the electromagnetic power absorption and its modelling by the bioheat equation is studied. The results of the thesis help to evaluate and identify the possible uncertainty factors and sources of error in computational RF dosimetry, which will produce new information on the reliability and repeatability of computational exposure assessment. Studying the uncertainty and accuracy of the methods also allows, for example, lessening the computational requirements and improving the accuracy of the simulations.