Biomedical applications at microwave and radio frequencies rely on the differences in permittivity and conductivity of biological tissues. The properties of healthy tissues span a wide range that relates to water content, while diseased tissues such as malignancies typically exhibit increased properties. Leveraging these differences, microwave imaging has been investigated as an alternative method for breast cancer detection and treatment monitoring. Several approaches have been developed to map the properties of tissues and identify anomalies. Microwave tomography involves measuring signals transmitted through the tissues, then iteratively updating properties of a model until simulations match these measurements. Radar-based approaches involve collecting reflections from tissues, then processing and focusing these reflections to identify anomalies. For both radar and tomography, key challenges are design of a measurement system and interface that enable reliable and rapid collection of data while operating close to the target tissues, developing imaging algorithms capable of detecting anomalies in a complex background, and reconciling the resulting microwave images with clinically available data. At the University of Calgary, we have developed several generations of prototype systems, focusing on demonstrating the consistency of images collected at different time points, as well as the feasibility of detecting tumors and treatment-related changes. Our most advanced radar-based system implements patient-specific capabilities, scanning the breast with 4 degrees of freedom in sensor positioning to enable consistent collection of data. We leveraged the knowledge gained through experience with this system to develop a novel approach that estimates locally averaged properties of tissues by detecting pulses traveling through the breast. With this approach, we have demonstrated a high degree of similarity between images captured at different time points, as well as symmetry between properties of the right and left breasts. Comparison of the images of right and left breasts of cancer patients has also enabled tracking treatment-related changes. Recently, our team began testing the next generation of this transmission system that features improved resolution. The initial results obtained with this system add to the growing body of work that illustrates the potential of microwave imaging to provide a unique breast imaging solution. Speaker(s): Prof. Elise Fear Room: BA1180, Bldg: Bahen Centre for Information Technology, 40 St George st, Toronto, Ontario, Canada
