INSTITUTE OF PHYSICS PUBLISHING PHYSICS IN MEDICINE AND BIOLOGY Phys. Med. Biol. 51 (2006) 1941–1955 doi:10.1088/0031-9155/51/7/022 Ultrawideband temperature-dependent dielectric properties of animal liver tissue in the microwave frequency range Mariya Lazebnik 1 , Mark C Converse 1,2 , John H Booske 1 and Susan C Hagness 1 1 Department of Electrical and Computer Engineering, University of Wisconsin, Madison, WI 53705, USA 2 Department of Surgery, University of Wisconsin, Madison, WI 53706, USA E-mail: lazebnik@cae.wisc.edu Received 27 October 2005, in final form 21 February 2006 Published 22 March 2006 Online at stacks.iop.org/PMB/51/1941 Abstract The development of ultrawideband (UWB) microwave diagnostic and therapeutic technologies, such as UWB microwave breast cancer detection and hyperthermia treatment, is facilitated by accurate knowledge of the temperature- and frequency-dependent dielectric properties of biological tissues. To this end, we characterize the temperature-dependent dielectric properties of a representative tissue type—animal liver—from 0.5 to 20 GHz. Since discrete-frequency linear temperature coefficients are impractical and inappropriate for applications spanning wide frequency and temperature ranges, we propose a novel and compact data representation technique. A single-pole Cole–Cole model is used to fit the dielectric properties data as a function of frequency, and a second-order polynomial is used to fit the Cole–Cole parameters as a function of temperature. This approach permits rapid estimation of tissue dielectric properties at any temperature and frequency. 1. Introduction The dielectric properties of biological tissues have been the subject of active research since the beginning of the 20th century. Fundamentally, the dielectric properties determine how electromagnetic fields will interact with and propagate within biological tissues. More practically, accurate knowledge of the dielectric properties of biological materials has a host of applications in the consumer, food/agricultural and biomedical industries. Some of these applications include characterizing and limiting human exposure to electromagnetic fields (Rosen et al 2002), determining how food products will heat in a microwave oven (Tran 0031-9155/06/071941+15$30.00 © 2006 IOP Publishing Ltd Printed in the UK 1941