Design of Fully-Digital Medical Ultrasound Imaging Systems

Ultrasound imaging is one of the most used clinical imaging modalities thanks to its real-time output, ease-of-use, portability and low cost. From its inception, ultrasound imaging strongly re- lied on hardware innovations to be the enabler for new imaging modalities and system architectures.
In this thesis, several hardware innovations for future ultrasound systems are explored that focus on replacing analog system parts with digital solutions. In a first part, fully-digital beamformers for 3D imaging are investigated as an alternative to replace existing mixed-signal solutions. In a second part, a new system architec- ture for software-defined 2D imaging is explored. To showcase the concept, a novel ultrasound probe was designed, which em- beds an entire 64-channel ultrasound front-end within the probe handle, and provides access to the digitized sensor data over a 25Gbit/s fiber-optics interface. This optical connector replaces the expensive analog cable harness used in conventional probes. The probe was then connected to an off-the-shelf PC equipped with a powerful GPU to demonstrate that advanced compute- intensive ultrasound modalities can be implemented at low cost.