Digital beamforming in ultrasound

Steinberg, Bernhard

doi:10.1109/58.165556

Cited by 140 publications

(72 citation statements)

References 7 publications

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“…The delay applied to each channel is calculated as the difference in the times of flight from the current focal point to the receive element for that channel and to the phase center of the aperture. The delay resolution, the quantizer precision, and the apodization of the aperture determine the quality of the beamforming [5]- [7]. For achieving sufficient delay resolution, interpolation between samples is used.…”

Section: Conventional Beamformer Architecturementioning

confidence: 99%

Compact FPGA-based beamformer using oversampled 1-bit A/D converters

Tomov

Jensen

2005

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Abstract-A compact medical ultrasound beamformer architecture that uses oversampled 1-bit analog-to-digital (A/D) converters is presented. Sparse sample processing is used, as the echo signal for the image lines is reconstructed in 512 equidistant focal points along the line through its in-phase and quadrature components. That information is sufficient for presenting a B-mode image and creating a color flow map. The high sampling rate provides the necessary delay resolution for the focusing. The low channel data width (1-bit) makes it possible to construct a compact beamformer logic. The signal reconstruction is done using finite impulse reponse (FIR) filters, applied on selected bit sequences of the delta-sigma modulator output stream. The approach allows for a multichannel beamformer to fit in a single field programmable gate array (FPGA) device. A 32-channel beamformer is estimated to occupy 50% of the available logic resources in a commercially available midrange FPGA, and to be able to operate at 129 MHz. Simulation of the architecture at 140 MHz provides images with a dynamic range approaching 60 dB for an excitation frequency of 3 MHz.

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Section: Conventional Beamformer Architecturementioning

confidence: 99%

Compact FPGA-based beamformer using oversampled 1-bit A/D converters

Tomov

Jensen

2005

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…The vast majority of commercial ultrasound scanners feature a digital beamformer and employ a delay-and-sum focusing of the digitized echo signals from the tissue [1]. The quality of the focusing is directly dependent on the timing precision with which it is done [2].…”

Section: Introductionmentioning

confidence: 99%

Scalable intersample interpolation architecture for high-channel-count beamformers

Tomov

Nikolov²,

Jensen

2011

2011 IEEE International Ultrasonics Symposium

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Abstract-Modern ultrasound scanners utilize digital beamformers that operate on sampled and quantized echo signals. Timing precision is of essence for achieving good focusing. The direct way to achieve it is through the use of high sampling rates, but that is not economical, so interpolation between echo samples is used. This paper presents a beamformer architecture that combines a band-pass filter-based interpolation algorithm with the dynamic delay-and-sum focusing of a digital beamformer. The reduction in the number of multiplications relative to a linear perchannel interpolation and band-pass per-channel interpolation architecture is respectively 58 % and 75 % beamformer for a 256-channel beamformer using 4-tap filters. The approach allows building high channel count beamformers while maintaining high image quality due to the use of sophisticated intersample interpolation.

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“…Several authors have addressed the issue of the allowed timing error for a given image quality [2]- [5]. From these studies, it is commonly assumed that timing resolution must be kept below 1/32 to 1/16 the fundamental period of the signal, which is equivalent to about four to eight times the Nyquist sampling frequency.…”

Section: Introductionmentioning

confidence: 99%

The progressive focusing correction technique for ultrasound beamforming

Fritsch¹,

Parrilla²,

Ibanez³

et al. 2006

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Abstract-This work presents a novel method for digital ultrasound beamforming based on programmable table look-ups, in which vectors containing coded focusing information are efficiently stored, achieving an information density of a fraction of bit per acquired sample. Timing errors at the foci are within half the period of a master clock of arbitrarily high frequency to improve imaging quality with low resource requirements. The technique is applicable with conventional as well as with ∆Σ converters.The bit-width of the focusing code and the number of samples per focus can be defined to improve both memory size and F# with controlled timing errors. In the static mode, the number of samples per focus is fixed, and in the dynamic approach that figure grows progressively, taking advantage of the increasing depth of focus. Furthermore, the latter has the lowest memory requirements.The technique is well suited for research purposes as well as for real-world applications, offering a degree of freedom not available with other approaches. It allows, for example, modifying the sampling instants to phase aberration correction, beamforming in layered structures, etc. The described modular and scalable prototype has been built using low-cost field programmable gate arrays (FPGAs). Experimental measurements are in good agreement with the theoretically expected errors.

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Digital beamforming in ultrasound

Cited by 140 publications

References 7 publications

Compact FPGA-based beamformer using oversampled 1-bit A/D converters

Compact FPGA-based beamformer using oversampled 1-bit A/D converters

Scalable intersample interpolation architecture for high-channel-count beamformers

The progressive focusing correction technique for ultrasound beamforming

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