Microwave Estimation of Dielectric Properties of Biological Tissue Under Thermal Modification

The aim of this study was to estimate changes of tissue dielectric parameters under the action of high temperature. We fixed the shifts of dielectric properties of biological tissue samples, associated with short-time influence of high temperature (600C, 5 min.) in vitro. The dielectric properties of tissues (permittivity - ε and conductivity - σ) were determined using original software and hardware complex for near-field resonant microwave sensing developed at the Institute of Applied Physics of the RAS. The study of these parameters was performed at a depth of 5 mm. It was found that short processing of a biological sample in moderate hyperthermia (600C) leads to significant change of dielectric characteristics of the tissue. This is manifested in a significant decrease in the dielectric permittivity (in 2.48 times for an intact specimen) and conductivity (on 25.3%) of the studied biological sample, due to its dehydration. It was shown that used regimen of heating decreases the permittivity and conductivity of tissue specimen that is associated with changes of its hydratation.