A Two-Stage Rotational Surface Clutter Suppression Method for Microwave Breast Imaging With Multistatic Impulse-Radar Detector

Radar-based microwave imaging is a promising technique for multiple medical applications, such as breast health monitoring, breast cancer detection, ablation monitoring, and chemotherapy monitoring. In our previous work, a hand-held multistatic CMOS impulse-radar detector was developed. It was designed to be placed directly on the patient in a supine position without a coupling medium. In the radar-based microwave breast imaging, the surface clutters, which are generated from skin reflection, imperfect contacts, and antenna coupling, deteriorate the imaging quality. This article proposes a two-stage rotational clutter suppression method for the multistatic rotational configuration of the radar detector. It consists of a signal selection stage and an adaptive filtering stage. The novelty of the proposed method is that a prior constraint using $L_{2}$ regularization is introduced to facilitate the filtering. Meanwhile, the antenna and channel variations are considered in the signal selection. The performance of the proposed method is verified in experiments with different surface conditions and patient trial. The results demonstrated that the proposed method is effective in suppressing the surface clutters and improving the image quality.