Evaluation of specific absorption rate and temperature elevation in a multi-layered human head model exposed to radio frequency radiation using the finite-difference time domain method

In this study, using the finite-difference time domain (FDTD) method, specific absorption rate (SAR) distributions and temperature increase are evaluated in a multi-layered human head model exposed to the field radiated from cellular phones and wireless local area networks (WLANs) antennas. The bioheat equation with suitable boundary conditions is solved to find temperature elevation and exposure time effect. Ageing effect is figured out too. In addition, the case of using cellular phones in enclosed areas is studied. Moreover, the effect of distance between the source and the head model is investigated. The obtained results confirm the importance of performing a thermal analysis along with the dosimetric one. At the same levels of radiated power, SAR levels in the tissues are less than the safety limit recommendations, except in skin and cerebrospinal fluid (CSF) tissues. It is also found that the induced temperature elevation in the brain region, in all the examined conditions, never exceeds 0.4°C. This value is well below the threshold for the induction of adverse thermal effects to the neurons.