Determination of the parameters of the Havriliak – Negami model for a breast phantom using a nonlinear optimization method

Early detection of breast tumors in risk groups requires long-term monitoring, including regular examinations. Existing methods have a number of disadvantages, for example, they carry radiation exposure to the body and are insufficiently accessible for mass screening. For these reasons, the development of non-invasive, safe and cost-effective diagnostic methods based on differences in the electrophysical properties of healthy and pathologically altered tissues is relevant. Work purpose – Determination of the parameters of the Havriliak-Negami model for breast phantoms in the study by the method of dielectric impedance spectroscopy in order to identify inhomogeneities in them. The main attention is paid to the detection of neoplasms based on changes in key parameters of the model characterizing the dielectric properties of tissues. Experimental studies of homogeneous and heterogeneous phantoms of the mammary gland with different sizes of inclusions were conducted using a two-electrode capacitive sensor. The components of the complex impedance were measured in the frequency range of 20 Hz – 2 MHz using a precision RLC meter. An original data processing technique was developed based on the analytical solution of the inverse problem for the Havriliak-Negami model using the least squares method. The possibility of detecting heterogeneities of various sizes in a biological object under the influence of a low-level sinusoidal electrical signal in a safe frequency range was experimentally confirmed. The results of the work demonstrate the prospects of the dielectric impedance spectroscopy method for creating portable devices for examining the mammary gland. The proposed method for calculating the parameters of the object model will improve the efficiency of early diagnostics by identifying changes in the dielectric parameters of tissues, which can be used as an additional screening tool.