Modified weighted back-projection algorithm (MWBP) for 3D electrical impedance mammography systems with the planar electrode array

Abstract

Electrical impedance mammography (EIM), as one of the EIT medical applications, is applied for diagnostics and imaging of the breast. Quality of reconstructed images in this method depends on precision of the EIM hardware and efficiency of the image reconstruction algorithm. One of the linearized methods in EIT image reconstruction is Weighted Back-Projection (WBP). The purpose of this paper is to present a novel method, which is a modified version of the current 3D WBP algorithm (MWBP), to improve the quality of reconstructed images in electrical impedance mammography. In order to calibrate the 3D WBP algorithm with regards to real equipotential surfaces and output results, some attempts have been made to model the real EIM conditions in terms of body shape and electrode positions by means of a saline-filled phantom. We have proposed a few modifications which improve the quality of images greatly, in terms of sensitivity, resolution, contrast, and accuracy in size and position of objects under imaging. The mentioned modifications contain: changing the problem assumptions, adding a new weighting function to the current 3D WBP equation, and defining an exciting radius for the pixel being reconstructed. The final results (containing phantom and in vivo images) prove the efficiency of the proposed modifications.