Design and implementation of a dual-mode ultrasound array driver.

Abstract

Ultrasound has a long history as an important medical diagnostic tool. Its non-ionizing nature and relative low cost has enabled this technology to gain widespread acceptance and use in hospitals worldwide. It's currently used to create images of many internal body structures allowing for rapid assessment by a physician. While it is in the diagnostic imaging context that ultrasound is most commonly used, it is however, not the only medical use of ultrasound. Ultrasound is also capable of non-invasively targeting organs and tissue for therapeutic benefits. These benefits can range from non-invasive drug delivery to tissue cauterization. Recent advances in piezocomposite transducer technology have allowed for a new generation of array transducers that are capable of both delivering ultrasound therapy, and imaging with the same device. These transducers, referred to as Dual-Mode Ultrasound Arrays (DMUAs), use the same elements for therapy and imaging, allowing for absolute registration between therapeutic and imaging coordinates. Therefore, realtime DMUA imaging provides unique form of feedback to the physician allowing her/him to identify and quantify the exposure to any obstacles in the path of the therapeutic beam. This feedback provides the basis for realtime resynthesis of the therapeutic beam to minimize the exposure to these obstacles while maximizing the exposure at the target. The advantages of the DMUA approach to image-guided surgery can be realized only with drivers that fully integrate the imaging and therapy functions in a seamless manner. This thesis describes the design and implementation of two real-time DMUA drivers. The first system was an enhancement of a previous design that allowed for the basic features of the DMUA system to be demonstrated. The second was a new design that allowed for a wider range of operation and the implementation of microsequencer to precisely control imaging and therapy sequences.