Parametric Beamformer for Synthetic Aperture Ultrasound Imaging

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    Abstract

    In this paper a parametric beamformer, which can handle all imaging modalities including synthetic aperture imaging, is presented. The image lines and apodization coefficients are specified parametrically, and the lines can have arbitrary orientation and starting point in 3D coordinates. The beamformer consists of a number of identical beamforming blocks, each processing data from several channels and producing part of the image. A number of these blocks can be accommodated in a modern field-programmable gate array device (FPGA), and a whole synthetic aperture system can be implemented using several FPGAs. For the current implementation, the input data is sampled at 4 times the center frequency of the excitation pulse and is match-filtered in the frequency domain. In-phase and quadrature data are beamformed with a sub-sample precision of the focusing delays of 1/16th of the sampling period. Each line is completely specified by 3 input parameters. The focusing delays are calculated iteratively in a 8-stage deep pipeline, and focusing information for 8 different lines is interleaved to produce delays at every clock cycle. The apodization is specified using piecewise linear approximation with 255 levels. A beamforming block uses input data from 4 elements and produces a set of 10 lines. Linear interpolation is used to implement sub-sample delays. The VHDL code for the beamformer has been synthesized for a Xilinx V4FX100 speed grade 11 FPGA, where it can operate at a maximum clock frequency of 167.8 MHz. Each beamformation block requires 12 multipliers, 5 buffers for parameters, 8 buffers for input data and 32 buffers for output data (I and Q). Furthermore double-buffering is used for the input data, thus simplifying the synchronization. Up to six beamforming blocks can fit in one FPGA. Clocked at 150 MHz they produce 900 x 106 I and Q samples/second. Assuming a pulse repetition frequency of 5000 Hz, these blocks can be configured to beamform in real time 256 B-mode lines of synthetic aperture data from 4 transducer elements, or 64 lines from 16 elements.
    Original languageEnglish
    Title of host publicationIEEE Ultrasonics Symposium
    PublisherIEEE
    Publication date2006
    Pages2172-2176
    ISBN (Print)978-1-4244-0201-4
    DOIs
    Publication statusPublished - 2006
    Event2006 IEEE Ultrasonics Symposium - Vancouver, Canada
    Duration: 2 Oct 20066 Oct 2006
    https://ieeexplore.ieee.org/xpl/conhome/4151855/proceeding

    Conference

    Conference2006 IEEE Ultrasonics Symposium
    Country/TerritoryCanada
    CityVancouver
    Period02/10/200606/10/2006
    Internet address

    Bibliographical note

    Copyright: 2006 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE

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