3-D EM Modeling of Medical Microwave Imaging Scenarios With Controllable Accuracy

Medical microwave imaging (MMWI) is a multidisciplinary task that requires precise electromagnetic modeling of heterogeneous human tissues, solving non-linear and ill-posed inverse scattering problems with weak contrasts, and design of compact antenna arrays well-matched to adjacent body parts. If any of the activities listed above does not perform well, the resulting imaging will be poor. In this article, we devote a special effort to achieving high accuracy in electromagnetic simulations of MMWI scenarios. This complex task requires developing a suitable meshing procedure, which balances model fidelity and computational bottlenecks such as a large number of unknowns in the electromagnetic model. Thus, instead of a simple conversion from triangles to quads, we offer a technique that generates high-quality mesh (in terms of both simulation speed and geometrical accuracy) with controllable deviation from the initial model. In addition, we developed a strategy for self-convergence tests that prove the reliability of the simulation results in the MMWI framework. Moreover, an additional validity test has been proposed, based on the inverse scattering operator, commonly used in many microwave imaging algorithms. The effectiveness of these novel techniques is demonstrated with the example of a 21-antenna system placed around the 5-tissue head phantom with and without stroke.