Fig. 6
Comparison of the SAR and thermal distributions from electromagnetic and thermal simulations of three applicator configurations positioned around the head of human voxel model “Ella” [27] with frequency dependent electromagnetic and thermal properties adjusted based on [31]. The configurations include an 8-channel applicator at 300 MHz (left), an 8-channel applicator at 500 MHz (middle) and a 20-channel applicator at 1 GHz (right). All three applicators were driven with a total input power of P in = 400 W, an in-phase (no phase shift between channels) phase setting, an RF heating duration of 3 min and a waterbolus temperature of TB = 20 °C. Maximum SAR1g in the center of the brain was 311 W/kg for 300 MHz, 240 W/kg for 500 MHz and 307 W/kg for 1 GHz. The maximum temperatures reached in the center of the brain were found to be T max = 46.8 °C at 300 MHz, T max = 44.5 °C at 500 MHz and T max = 45.3 °C at 1GHz while surface regions exhibited temperatures below 43 °C (41 °C for 300 MHz, 39.3 °C for 500 MHz and 42.9 °C for 1 GHz)