Multi-channel pre-beamformed data acquisition system for research on advanced ultrasound imaging methods

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control ferroelectrics, and frequency control, 2012-02, Vol.59 (2), p.243-253
• Main Authors: Cheung, Chris C. P., Yu, Alfred C. H., Salimi, Nazila, Yiu, Billy Y. S., Tsang, Ivan K. H., Kerby, Benjamin, Azar, Reza Zahiri, Dickie, Kris
• Format: Article
• Language: English
• Subjects: Acoustic signal processing; Acoustics; Arrays; Beamforming; Channels; Connectors; Data acquisition; Data acquisition systems; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Gain; Imaging; Physics; Receivers; Scanners; Transduction; acoustical devices for the generation and reproduction of sound; Ultrasonic imaging; Ultrasound
• ISSN: 0885-3010; 1525-8955; 0885-3010
• DOI: 10.1109/TUFFC.2012.2184

The lack of open access to the pre-beamformed data of an ultrasound scanner has limited the research of novel imaging methods to a few privileged laboratories. To address this need, we have developed a pre-beamformed data acquisition (DAQ) system that can collect data over 128 array elements in parallel from the Ultrasonix series of research-purpose ultrasound scanners. Our DAQ system comprises three system-level blocks: 1) a connector board that interfaces with the array probe and the scanner through a probe connector port; 2) a main board that triggers DAQ and controls data transfer to a computer; and 3) four receiver boards that are each responsible for acquiring 32 channels of digitized raw data and storing them to the on-board memory. This system can acquire pre-beamformed data with 12-bit resolution when using a 40-MHz sampling rate. It houses a 16 GB RAM buffer that is sufficient to store 128 channels of pre-beamformed data for 8000 to 25000 transmit firings, depending on imaging depth; corresponding to nearly a 2-s period in typical imaging setups. Following the acquisition, the data can be transferred through a USB 2.0 link to a computer for offline processing and analysis. To evaluate the feasibility of using the DAQ system for advanced imaging research, two proof-of-concept investigations have been conducted on beamforming and plane-wave B-flow imaging. Results show that adaptive beamforming algorithms such as the minimum variance approach can generate sharper images of a wire cross-section whose diameter is equal to the imaging wavelength (150 μm in our example). Also, plane wave B-flow imaging can provide more consistent visualization of blood speckle movement given the higher temporal resolution of this imaging approach (2500 fps in our example).