Estimation of an error of the SAR caused by inaccurate electric constants of the biological tissue-equivalent phantom

Experimental evaluation methods for the specific absorption rate (SAR) using the biological tissue-equivalent phantom have been proposed. In these methods, however, differences of electric constants between the phantom and the human tissue cause an error on the SAR. In this paper, we investigate the effect of inaccurate electric constants of the biological tissue-equivalent phantom on the SAR in the human head model at 900 MHz. From this investigation, we have made it clear that the error of the local peak SAR is proportional to the inaccuracy of the electric constants. In addition, good agreement of the calculated and measured SAR distributions has been obtained when only the conductivity of the phantom is varied. Furthermore, we have confirmed that agreement of the conductivity between the phantom and the human tissue within /spl plusmn/5% is indispensable to the precision evaluation where the error caused by the inaccurate electric constants is within 5%.