A Radar-Tomographic Bidirectional Method for Quantitative Microwave Breast Imaging

A bidirectional processing method using radar and tomography approaches is proposed to achieve an accurate dielectric profile reconstruction for breast cancer microwave imaging. We introduce a tomography-enhanced radar approach to obtain accurate radar profiles for highly heterogeneous media, where Green's function and clutter components, such as skin reflection, are effectively reconstructed using a contrast source inversion (CSI)-based tomography scheme, that is, "tomography $\rightarrow $ radar" process. Furthermore, this method introduces a radar-enhanced CSI approach to provide accurate dielectric profiles using an appropriate initial estimate through an accuracy-enhanced radar image. The aforementioned bidirectional processing between radar and tomography consequentially upgrades the reconstruction performance of quantitative imaging (i.e., complex permittivity profile reconstruction) for breast media (radar $\rightarrow $ tomography process), which would improve the recognition rate for cancerous tissues. The finite-difference time-domain (FDTD)-based numerical test, using realistic breast phantoms, demonstrated that the proposed approach considerably enhances the reconstruction accuracy in permittivity and conductivity.