Artifact Reduction Strategy for Radar-based Microwave Imaging Designed for Medical Applications
Date
2021-08-24
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Abstract
This thesis involves investigating the frequency domain data obtained from Tissue Sensing Adaptive Radar (TSAR), which is a near-field ultra-wideband radar imaging technique using microwaves that has potential as a new breast imaging modality. Domain transformations of the acquired data result in Gibbs’ distortions which can propagate through the data processing flow. These distortions or artifacts can be reduced by filtering the frequency data but with a loss in time domain resolution. Fourier Shift Manipulation (FSM) was explored as an alternative pre-processing technique that utilizes fundamental discrete Fourier transform (DFT) properties to shift the sampling locations of the signal, leading to artifact reduction with minimal loss of resolution. The extent of the removal of Gibbs’ artifacts led to investigations into specific improvements in the initial time-domain signals which were subsequently used for image formation. Further exploration involved the propagation of these distortions through the data flow and the impact they have on the clutter response in the final reconstructed images. The artifact reduction techniques were initially tested on simple simulated models, then extended to more complex datasets and finally patient data. Existing metrics were used to compare the outputs from these approaches, and new ones developed wherever necessary. The differences in the resulting images were compared with an emphasis on the degree of tumour detection. Future research would involve evaluating the compatibility of FSM with other image reconstruction algorithms, as well as modifying the removal of an inherent skin-breast artifact.
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Signal Processing, Image Processing, Imaging, Microwave Imaging, Gibbs' artifacts, Ringing artifacts, Artifact reduction, Fourier, Fourier Shift Manipulation
Citation
DasGupta, I. (2021). Artifact Reduction Strategy for Radar-based Microwave Imaging Designed for Medical Applications (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.