Real-Time Microwave Imaging of a Compressed Breast Phantom With Planar Scanning

Two real-time reconstruction algorithms, i.e., quantitative microwave holography and scattered-power mapping, have been shown to be successful in the imaging of compressed tissue of relatively small thicknesses such as 1 and 2 cm. In both cases, planar data acquisition of frequency-swept transmission coefficients has been employed. Despite the fact that these algorithms are based on a linear forward model of scattering, they have been capable of providing quantitative estimates of the tissue permittivity due to the experimentally derived kernel of the scattering integral. Here, we demonstrate similar performance with a thicker (approximately 5 cm) compressed-breast phantom. This thickness is greater than or comparable to the median thickness employed in mammography, depending on the view (craniocaudal or mediolateral oblique). The two methods are described in a common mathematical framework for the first time. The importance of the system calibration and the choice of a host medium are discussed through experiments. A new method for focusing onto suspect regions is demonstrated. The limitations of real-time imaging are highlighted, along with an outlook to improve the image resolution and suppressing artifacts without sacrificing the reconstruction speed. Future work aims at validation with high complexity, realistic compressed-breast phantoms.