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Real-time Microwave Imaging of Differential Temperature for Thermal Therapy Monitoring

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Mark Haynes, John Stang, and Mahta Moghaddam, University of Southern California
Volume 61, Issue 7, Page: 1787-1797

July Haynes TBME_feature_animation

In this work, we present the development of a real-time 3D noninvasive microwave thermal monitoring method.  Thermal therapies have seen increased use in the treatment of a variety of diseases, particularly subcutaneous cancers of soft tissue.  As thermal treatment systems have evolved, research in thermal monitoring techniques has followed, particularly in the areas of ultrasound and MRI.  However, increased cost and complexity are inherent to such dual modality systems, and integration of monitoring and therapy systems that employ separate modalities is cumbersome.  To address these limitations, we have developed an imaging method based on differential scattered field measurements to detect the change in the dielectric properties of water due to temperature variation.  In our prototype system, a precomputed linear inverse scattering solution is combined with continuous Vector Network Analyzer (VNA) measurements of a 36-antenna, full-wave modeled, cylindrical cavity.  We achieve centimeter spatial resolution with 0.5 oC sensitivity at 4-second refresh rates in simple phantoms over hyperthermia and ablation temperature ranges.  This integrated approach enables direct monitoring of subcutaneous microwave heat deposition at a resolution and speed necessary for closed-loop feedback of microwave thermal treatment.
Keywords: Microwave imaging, hyperthermia, thermal ablation, breast imaging, inverse scattering, Born Approximation, Distorted Born Approximation, thermal monitoring

Research website: http://mixil.usc.edu

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