Bernardi Paolo, Cavagnaro Marta, Pisa Stefano, Piuzzi Emanuele
Department of Electronic Engineering, University of Rome La Sapienza, Via Eudossiana 18, 00184 Rome, Italy.
IEEE Trans Biomed Eng. 2003 Mar;50(3):295-304. doi: 10.1109/TBME.2003.808809.
The exposure of a subject in the far field of radiofrequency sources operating in the 10-900-MHz range has been studied. The electromagnetic field inside an anatomical heterogeneous model of the human body has been computed by using the finite-difference time-domain method; the corresponding temperature increase has been evaluated through an explicit finite-difference formulation of the bio-heat equation. The thermal model used, which takes into account the thermoregulatory system of the human body, has been validated through a comparison with experimental data. The results show that the peak specific absorption rate (SAR) as averaged over 10 g has about a 25-fold increase in the trunk and a 50-fold increase in the limbs with respect to the whole body averaged SAR (SARWB). The peak SAR as averaged over 1 g, instead, has a 30- to 60-fold increase in the trunk, and up to 135-fold increase in the ankles, with respect to SARWB. With reference to temperature increases, at the body resonance frequency of 40 MHz, for the ICNIRP incident power density maximum permissible value, a temperature increase of about 0.7 degrees C is obtained in the ankles muscle. The presence of the thermoregulatory system strongly limits temperature elevations, particularly in the body core.
对处于10 - 900兆赫兹范围内运行的射频源远场中的受试者暴露情况进行了研究。利用时域有限差分法计算了人体解剖学异质模型内部的电磁场；通过生物热方程的显式有限差分公式评估了相应的温度升高。所使用的考虑人体体温调节系统的热模型已通过与实验数据的比较得到验证。结果表明，相对于全身平均比吸收率（SARWB），10克平均的峰值比吸收率在躯干中增加约25倍，在四肢中增加50倍。相反，1克平均的峰值比吸收率相对于SARWB在躯干中增加30至60倍，在脚踝处增加高达135倍。关于温度升高，在40兆赫兹的人体共振频率下，对于国际非电离辐射防护委员会（ICNIRP）入射功率密度最大允许值，脚踝肌肉中温度升高约0.7摄氏度。体温调节系统的存在强烈限制了温度升高，特别是在身体核心部位。
