Near-field microwave tomography of biological objects

A method of finding the subsurface temperature distribution in biological media from near-field microwave probing data is suggested. The electrodynamic problem of probe response to a temperature profile disturbance ΔT(z) in a medium is solved. An integral equation that relates the shift of the resonant frequency of the probe to the function ΔT(z) is derived. The effective near-field probing depth is shown to depend on the probe aperture, its elevation above the surface, and the wavelength. In this method, several probes operate simultaneously, receiving signals from different depths, and the temperature profile is reconstructed by inverting the related integral equation. The components and parameters of a measuring facility that provides the temperature profi le reconstruction accurate to 0.5°C to a depth of up to 5 cm are established. The procedure of near-field diagnostics is simulated in a computer experiment to check the accuracy predicted. Calculation is performed based on a model of permittivity of biological media.