"Design, Calibration, and Inversion Algorithms for Novel Microwave Tomography Systems"

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The main research goal of this proposed research program is to improve the performance of Microwave Tomography (MWT) systems for biomedical imaging applications. MWT uses microwave measurements to create a quantitative image of the bulk-electrical material properties of an object-of-interest (OI); typically the complex permittivity of the OI. In biomedical applications the OIs are typically in situ regions of the human body and the goal is to use the constructed complex permittivity maps to identify abnormal or diseased tissue in that region, e.g., the imaging and detection of cancerous tissue. The unique advantage of MWT for biomedical diagnostic imaging is that the reconstructed permittivity map is not directly imaged in any other modality and therefore contains unique and complementary information upon which to base a diagnosis. For biomedical applications, the greatest performance issue with current state-of-the-art MWT systems is the limited spatial resolution compared to other imaging modalities such as CT and MRI. In order to be a viable modality the achievable resolution of MWT must be increased while retaining the accuracy of the reconstructed complex permittivity maps. To achieve this goal the proposed research will investigation the three main aspects of MWT: a) the inversion algorithms used to create the images from appropriately calibrated scattered field data, b) the calibration techniques which take raw measurements from the MWT systems and produce appropriate data for the inversion algorithms, and c) the MWT system set-ups themselves which affect the electromagnetic (EM) model which must be used as well as the calibration procedure. These three aspects of MWT are interrelated, in sometimes subtle ways, and it is a fundamental thesis of this proposed research that a substantial enhancement of current MWT imaging performance can only be accomplished via the joint study of these three aspects.