Memory efficient method of calculating specific absorption rate in CW FDTD simulations

Specific absorption rate (SAR) distributions in man models are often calculated using the finite-difference time-domain (FDTD) method. The traditional method of calculating SAR requires calculation and storage of the three electric field components in each cell and is therefore very time- and memory-intensive. A new algorithm, based on the mass-normalized time-averaged energy distribution, is presented in this paper. This new method of calculating SAR requires 1/6 of the memory and a small fraction of the computer time of the traditional method. The accuracy of the two methods is shown to be virtually identical. In addition to improving the efficiency of SAR distribution calculations, the memory requirements are virtually eliminated for calculations of layer-averaged or organ-averaged SAR.