Advanced Technologies for Next Generation Open Ultrasound Research Platforms

Widespread availability of ultrasound Open Platforms (OPs) to research groups has allowed for an expansion of applications for ultrasound imaging and therapy. Underpinning this research are advances in technology of the systems themselves, with multiple companies and institutes developing their own platforms, both general purpose and application specific. There is continued drive towards higher frequencies, higher power, and higher channel counts, with a large technological burden placed on the research platforms to enable these applications. This thesis looks towards new technologies for these systems through the expansion of the Ultrasound Array Research Platform (UARP), an ultrasound OP developed at the University of Leeds.

This thesis first compares and contrasts existing ultrasound platforms, both commercial and academic, before identifying areas in which the development of new technologies could allow for improved performance or enable new applications. The first of these documents the development of a high frequency back-end for the acquisition of time-multiplexed data for imaging catheter applications, part of an international collaboration, with a full end-to-end imaging catheter system demonstrated. Focus then shifts towards improving the transmit capabilities of the UARP, with the aim of transmitting at both higher powers and frequencies. A new Gallium-Nitride (GaN) based switched-mode transmitter technology, suitable for High-Intensity Focused Ultrasound (HIFU), High-Frequency Ultrasound (HFUS), and diagnostic imaging applications is presented. The thesis further considers real-time techniques for monitoring the output power of a HIFU transmitter, as well as normalisation of the analogue front end, and monitoring of transducer health. Finally, the design process and construction of two new systems is documented, one for industrial applications such as process measurement, and the other a mixed modality imaging and HIFU system which provides a technology test-bed for a future high channel count system.