Abdilla Lourdes, Sammut Charles, Mangion Louis Zammit
Electromagnetics Laboratory, Department of Physics, University of Malta, Msida, Malta.
Electromagn Biol Med. 2013 Jun;32(2):244-52. doi: 10.3109/15368378.2013.776436.
Dielectric properties are the most important parameters determining energy deposition when biological tissues are exposed to radio frequency and microwave fields. Energy absorption is determined by the specific absorption rate (SAR). SAR distributions can be computed accurately only if the complex relative permittivity of the target tissue is known to a sufficiently high accuracy, and currently there is a lack of data on the dielectric properties of biological tissues at high frequencies. In this study, tissue dielectric properties are measured using an open-ended coaxial probe technique from 500 MHz up to 40 GHz. We present dielectric data for ex vivo bovine and porcine muscle and liver tissues at 37 °C. One-pole Cole-Cole model is used to fit the measured data as a function of frequency and the dispersion parameters are presented. This data is supported by an accurate study on reference liquids such as methanol and ethanediol.
当生物组织暴露于射频和微波场时,介电特性是决定能量沉积的最重要参数。能量吸收由比吸收率(SAR)决定。只有在目标组织的复相对介电常数已知且精度足够高时,才能准确计算出SAR分布,而目前高频下生物组织介电特性的数据尚显不足。在本研究中,使用开口同轴探头技术在500 MHz至40 GHz范围内测量组织介电特性。我们给出了37°C下离体牛和猪肌肉及肝脏组织的介电数据。采用单极Cole-Cole模型将测量数据拟合为频率的函数,并给出了色散参数。该数据得到了对甲醇和乙二醇等参考液体的精确研究的支持。