Dielectric spectroscopy of breast tissue: measurement and permittivity models

Abstract

Microwave breast cancer detection applications are based on the hypothesis that there is a clear distinction between normal and malignant breast tissue dielectric properties across a wide frequency range. There is need for a database of the dielectric properties of breast tissue, as limited data has been collected to date. Measurement protocols have been developed for collecting the reflection coefficient of breast tissue using a high precision coaxial probe and vector network analyzer. Data processing techniques have been developed to extract permittivity from reflection coefficient data measured through dielectric spectroscopy. A rational func­tion model (RFM), dependent on frequency and permittivity, converts the aperture plane reflection coefficient to permittivity. Validation studies were conducted using breast tissue equivalent reference liquids. The RFM model has been preliminarily applied to measured breast tissue sam­ples. The initial results support the hypothesis of a fundamental difference between normal fat and malignant and benign tissues, as well as a distinction between benign fibroadenoma and malignant tissues.