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Comparison of the microwave medical antennas

Keywords:

S.G. Vesnin, M.K. Sedankin


Software for mathematical modeling of human body's own radiation in the microwave range was developed. Software based on the numerical solution of Maxwell's equations in multilayer lossy medium, and the numerical solution of heat equations with blood flow. With the developed tool of mathematical modeling of antennas used in microwave radiometry: the antenna on the basis of circular and rectangular waveguides with different diameters, a rectangular printed circuit antenna, loop antenna and a printed slot antenna. The model of a biological object consisted of several layers, namely, glandular tissue, adipose tissue, skin, malignant tumor. Each layer is characterized by its thermal emission model, the parameters of blood flow, thermal conductivity, permittivity and electrical conductivity. The solution of the heat conduction equation was conducted using COMSOL Multiphysics 3.5. Based on the numerical solution of heat conduction equation was obtained by a simple approximation formula for the temperature distribution in biological tissue in the presence of a malignant tumor. The resulting analytical temperature distribution was used to calculate the self-radiation of tissues. To calculate the electromagnetic field in the tumor and surrounding tissues of the breast used the program CST Microwave Studio 2010 that allows to solve numerically the Maxwell equation for multilayer structures with losses. The technique is described, which allows to compare different antenna applicators, based on characteristic of new antenna (depth and size of the measurement, resolving power, brightness temperature, etc.). The comparison antenna shown that miniature antenna built on the basis of a circular waveguide filled with dielectric with high dielectric constant, at shallow depths have better resolution compared to the large diameter antennas. In this way, they are able to more effectively detect temperature anomalies of small dimensions, not located a short distance from the skin. In particular, we recommend the use of these antennas for the diagnosis of diseases of the thyroid gland for the diagnosis of inflammatory diseases of ear, nose and throat. Waveguide antennas with diameters 32 and 38 mm is better detect tumors located at greater depths.
References:
Sept. 2, 2020
Aug. 27, 2020
June 24, 2020

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