Stochastic Method for the Determination of Organ-Specific Averaged SAR in Realistic Environments at 950 MHz

The organ-specific averaged specific absorption rate (SARosa) in a heterogeneous human body phantom, the Virtual Family Boy, is determined for the first time in (five) realistic electromagnetic environments at the Global System for Mobile communications downlink frequency of 950 MHz. We propose two methods, based upon a fixed set of finiteStochastic Method for the Determination of Organ-Specific Averaged SAR in Realistic Environments at 950 MHz Arno Thielens*, Günter Vermeeren*, Wout Joseph*, and Luc Martens* (email:[email protected], tel : +32 9 33 14918, fax:+32 9 33 14899) *Department of Information Technology, Ghent University / iMinds Gaston Crommenlaan 8, B-9050 Ghent, Belgium difference time-domain (FDTD) simulations, for generating cumulative distribution functions for the SARosa in a certain environment: an accurate vectorial cell-wise spline interpolation with an average error lower than 1.8% and a faster scalar linear interpolation with a maximal average error of 14.3%. These errors are dependent on the angular steps chosen for the FDTD simulations. However, it is demonstrated that both methods provide the same shape of the cumulative distribution function for the studied organs in the considered environments. The SARosa depends on the considered organ and environment. Two factors influencing the SARosa are investigated for the first time: the conductivity over density ratio of an organ and the distance of the organ’s center of gravity to the body’s surface and the exterior of the phantom. A non-linear regression with our model provides a correlation of 0.80. The SARosa due to single plane-wave exposure is also investigated: a worst-case single plane-wave exposure is determined for all studied organs and has been compared with realistic SARosa values. There is no fixed worst-case polarization for all organs and for the studied organs a single plane-wave exposure condition that exceeds 91% of the SARosa values in a certain environment can always be found. Key Wordsorgan-specific averaged SAR, realistic electromagnetic environment