Three-Dimensional Microwave Imaging: Fast and Accurate Computations with Block Resolution Algorithms

Abstract

This paper considers the microwave imaging reconstruction problem, based on additive penalization and gradient-based optimization. Each evaluation of the cost function and of its gradient requires the resolution of as many high-dimensional linear systems as the number of incident fields, which represents a large amount of computations. Since all such systems involve the same matrix, we propose a block inversion strategy, based on the block-biconjugate gradient stabilized (BiCGStab) algorithm, with efficient implementations specific to the microwave imaging context. Numerical experiments performed on synthetic data and on real measurements show that savings in computing time can reach a factor of two compared to the standard, sequential, BiCGStab implementation. Improvements brought by the block approach are even more important for the most difficult reconstruction problems, that is, with high-frequency illuminations and/or highly contrasted objects. The proposed reconstruction strategy is shown to achieve satisfactory estimates for objects of the Fresnel database, even on the most contrasted ones.

Existing and Emerging Breast Cancer Detection Technologies and Its Challenges: A Review

“…Furthermore, if tumorous, tissue of the same kind will have differing dielectric characteristics. Because of this variation, the interaction of EM signals in various tissues will be different [71]. Varied reconstruction techniques may use this to create an image, in 2D or 3D, that displays additional tissue dielectric characteristics or a tumor's location within the body [72].…”

Improved Methods for Fourier-Based Microwave Imaging

“…They are of special interest in non-destructive testing (NDT) applications [1], e.g., security screening systems for concealed weapon detection [2][3][4], or biomedical applications [5]. Different kinds of microwave imaging algorithms have been developed; some of them, like the backpropagation delay-and-sum (DAS) [6] or Fourier-based algorithms [7,8] are widely used thanks to their efficiency in terms of computational cost and simplicity with respect to those based on full-wave Equations (inverse fast multipole method [9], subspace-based optimization method [10], or gradient-based optimization [11], among others). In these algorithms, the measurements of the field scattered by the targets on the imaging domain are coherently processed to form the microwave image.…”