SAR calculations from 20 MHz to 6 GHz in the University of Florida newborn voxel phantom and their implications for dosimetry.

This paper presents finite-difference time-domain (FDTD) calculations of SAR in the University of Florida newborn female model. The newborn model is based upon a surface representation of the organs of the body, using non-uniform rational B-spline surfaces (NURBS). The surface model can then be converted into voxels at any resolution required. This flexibility allows the preparation of voxel models at 2, 1 and 0.5 mm to investigate the effect of resolution on dispersion and the choice of algorithms to calculate SAR in the Yee cell as the frequency increases up to 6 GHz. The added advantage of the newborn model is that it is relatively small and so FDTD calculations can be made tractable at a very fine resolution of 0.5 mm. A comparison is made between the calculated external electric fields required to produce the basic restriction on whole-body-averaged SAR and the ICNIRP reference levels for public exposure. At 250 MHz, the whole body resonance, the ICNIRP reference level does not provide a conservative estimate of the whole-body-averaged SAR restriction. The reference level is also breached in the range 700-2450 MHz by all of the irradiation geometries considered.