Real-time beam visualization and therapy planning for focused ultrasound therapies using a diagnostic imaging array
Focused ultrasound (FUS) is a non-invasive treatment modality that can produce therapeutic effects in localized regions of tissue through thermal elevations or mechanical stresses caused by an ultrasound wave. Although FUS therapy is effective at treating many different diseases, FUS therapy can be expensive and time-consuming because the treatment must be planned and monitored using guidance technologies such as magnetic resonance imaging (MRI). Pre-therapy planning and real-time monitoring during treatment are crucial to ensure that healthy tissues are not affected by the FUS beam. To provide a cost-effective method for FUS therapy monitoring, we present a novel technique for real-time visualization of an FUS beam using ultrasonic backscatter. A diagnostic imaging array was used to receive backscatter from an FUS beam interacting with tissue and the backscatter was processed to reconstruct the intensity field of the FUS beam. The intensity field reconstruction was then overlaid onto a co-aligned B-mode image captured using the same imaging array to provide anatomical context. To correct for the scattering profile of the medium, the echogenicity of the B-mode image was used to normalize the intensity field reconstruction, allowing for robust beam visualizations even in non-homogeneous media. The beam visualization technique was demonstrated at a frame rate of 25-30 frames per second in a tissue-mimicking phantom and in a rat tumor in vivo while a mock FUS therapy was administered. To facilitate quick and cost-effective therapies, a system for combined therapy planning, real-time beam visualization, and low intensity FUS treatment using a single imaging array was also designed. The therapy planning and beam monitoring capabilities of this system were demonstrated in a tissue-mimicking phantom and in vivo. Passive cavitation detection (PCD) measurements found that an imaging array can induce stable cavitation in microbubbles and could therefore be used to administer some low intensity FUS treatments.
Focused ultrasound, Therapy monitoring, Therapy planning
University of Illinois - Urbana-Champaign
Networked Digital Library of Theses and Dissertations
University of Illinois at Urbana-Champaign