ULA-OP 256: A 256-channel open scanner for development and real-time implementation of new ultrasound methods

Open scanners offer an increasing support to the ultrasound researchers who are involved in the experimental test of novel methods. Each system presents specific performance in terms of number of channels, flexibility, processing power, data storage capability and overall dimensions. This paper reports the design criteria and hardware/software implementation details of a new 256-channel ULtrasound Advanced Open Platform (ULA-OP 256). This system is organized in a modular architecture including multiple front-end boards, interconnected by a high-speed (80 Gbit/s) ring, capable of finely controlling all transmit and receive signals. High flexibility and processing power (equivalent to 2500 GFLOPs) is guaranteed by the possibility of individually programming multiple DSPs and FPGAs. 80 GB of on-board memory are available for storage of pre-, post-beamforming and baseband data. The use of latest generation devices allowed to integrate all needed electronics in a small size (34 x 30 x 26 cm). The system implements a multi-line beamformer that allows obtaining images of 96 lines by 2048 depths at a frame rate of 720 Hz (expandable to 3000 Hz). The multi-line beamforming capability is also exploited to implement a real-time vector Doppler scheme in which a single transmit and two independent receive apertures are simultaneously used to maintain the analysis over a full PRF range.