An investigation of the variation of dielectric properties of ovine lung tissue with temperature

Abstract

Presently, lung cancer is the leading cause of cancer deaths. Microwave thermal ablation is commonly used for the treatment of lung cancer. During microwave ablation treatment, changing temperatures (up to 100 °C) cause variations in the dielectric properties of the tissue under treatment. This study investigates the temperature dependence of dielectric properties of ex-vivo ovine lung tissue. The frequency spectrum investigated was from 0.5 GHz to 8 GHz over a total of 201 points. In this study, a microwave ablator (MWA) and a microwave oven (MWO) were used to warm up the samples under investigation. Initially, the spectral variation of the dielectric properties with temperature are presented. The results show that both the real part of the permittivity and the conductivity decrease with temperature for both heating methodologies. The study also investigates the effect of the heating methodology on the measurements. In this case, MWA heating results in a wider range in the measured dielectric parameters compared to MWO. However, the average values for both methodologies are within experimental uncertainty. Finally, the study also presents the temperature coefficients for both the MWA and the MWO tissue heating methods. These results are useful in treatment planning of thermal ablation procedures in order to minimise thermal damage to peripheral tissue.