%0 PDF %T Cavitation control and imaging for focused ultrasound brain therapy %A Sun, Tao. %D 2018-10-09T07:38:27.197-04:00 %8 2018-10-09 %R http://localhost/files/0k225p43f %X Abstract: Cavitation-mediated focused ultrasound (FUS) is currently the only method of reversible blood-brain barrier disruption (BBBD) for targeted drug delivery without incision or radiation. A significant challenge for its clinical translation is a lack of reliable and precise real-time treatment control and imaging methods, especially in brain applications where B-mode ultrasound and magnetic resonance imaging are unable to visualize microbubble sources transcranially and tissue temperature change in deep brain targets. This thesis develops several acoustic methods to improve the low-frequency FUS focusing, the feedback control of cavitation behavior and drug delivery thereof, and the localization ability of passive cavitation imaging (PCI). Firstly, to maximize the clinical relevance of small animal investigations, a dual-aperture FUS system was designed for low-frequency (274.3kHz) cavitation-mediated FUS therapy via temporal modulation of the wave interference pattern. In addition, a closed-loop, real-time control paradigm is shown capable of sustaining stable microbubble oscillations at a preset level while minimizing transient and violent microbubble collapsing that may result in vascular damage. After optimizing key ultrasound parameters and microbubble administration protocols, this cavitation controller was investigated to realize on-demand drug delivery with modulated BBBD. Tested at clinically relevant frequency in healthy and tumor-bearing rats, our approach enables targeted delivery of predefined drug concentrations within a therapeutically effective range in both normal tissue and glioma, while maintaining a safe exposure level. Finally, to refine the localization ability of traditional PCI, adaptive beamforming methods with diagonal loading were applied to the imaging algorithm. A white noise gain constraint was used to adaptively control the loading level so that the sensitivity of minimum variance distortionless response beamformer can be adjusted in a spatially selective manner, which result in significant improvement in image resolution and contrast.; Thesis (Ph.D.)--Tufts University, 2018.; Submitted to the Dept. of Electrical Engineering.; Advisors: Eric Miller, and Nathan McDannold.; Committee: Brian Tracey, and Paul Barbone.; Keywords: Electrical engineering, Acoustics, and Biomedical engineering. %[ 2022-10-11 %9 Text %~ Tufts Digital Library %W Institution