Three-dimensional Distorted Born Iterative Method Enhanced by Breast Boundary Extraction for Microwave Mammography

Microwave mammography has several advantages e.g. portability, non-contact and cell-friendly measurement, and low cost for the equipment. Therefore, this technology has been regarded as a more frequent screening technique, than the Xray based modality. This paper focuses on the dependence of the imaging accuracy, which is obtained using inverse scattering algorithms, on the estimation of the breast boundary. The Envelope method has been proposed as a method of using microwaves to estimate the location of the breast boundary. The accuracy of the boundary estimation via the Envelope method depends on that of the time-delay estimation, which is mostly processed by a filter based on waveform matching between the observed and reference signals. However, the coupling effect between the antenna and breast surface deforms the observed waveforms relative to the reference waveform. To mitigate this problem, this paper introduces the finite-difference time domain (FDTD)-based waveform correction assuming the three-dimensional (3-D) distorted Born iterative method (DBIM) analysis. The 3-D numerical simulations based on realistic breast phantoms demonstrate that the proposed method enhances the accuracy for the 3-D reconstruction of the dielectric profile in highly heterogeneous cases.