Transmission-Based Radar-System for UWB Breast Cancer Imaging: A Study of Application to Patients

Breast cancer detection at microwave frequencies benefits from the non-ionizing nature of microwave radiation and, thus, enables more frequent check-ups compared to X-ray mammography. Various algorithms exist in the literature to construct a qualitative radar image in which the highest intensity corresponds to the tumour location. A drawback of such a radar image is the missing physical interpretability. In addition, most of these image reconstruction techniques employ the effective permittivity of the breast tissue to form a map of scatterers in the generally heterogeneous breast tissue. Therefore, the quality of the tumor detection and localization in the final image is generally related to the accuracy of the estimated permittivity.In this paper, measurements from patients are presented based on a newly designed transmission-based ultra-wideband (UWB) radar system operating in the frequency range from 1 to 9 GHz. Two algorithms for quantitative breast cancer imaging are proposed which do not have the limitations of related techniques mentioned above. The first method shows a relative permittivty map of breast tissue in which the area with the highest permittivity can be recognized as malignant tissue. In the second method, signal attenuations in breast tissue are computed to localize the tumor as the location with the highest signal decay. Finally, those microwave images are compared to the corresponding X-ray images recorded in a patient study.