Apodization scheme for hardware-efficient beamformer

IEEE Trans. Biomed. Circuits Syst.

Zhang

Angiolini

et al. 2018

Ultrasound imaging is a ubiquitous diagnostic technique, but does not fit the requirements of the telemedicine approach, because it relies on the real-time manipulation and image recognition skills of a trained expert, called sonographer. Sonographers are only available in hospitals and clinics, negating or at least delaying access to ultrasound scans in many locales-rural areas, developing countries-as well as in medical rescue operations. Telesonography would require an advanced imager that supports three-dimensional (3-D) acquisition; this would allow untrained operators to acquire broad scans and upload them remotely for diagnosis. Such advanced imagers do exist, but do not meet several other requirements for telesonography, such as being portable, inexpensive, and sufficiently low power to enable battery operation. In this work, we present our prototype of the first portable 3-D digital ultrasound back-end system. The prototype is implemented in a single midrange Xilinx field programmable gate array (FPGA), for an estimated power consumption of 5 W. The device supports up to 1024 input channels, which is state of the art and could be scaled further, and supports multiple image reconstruction modes. We evaluate the resource utilization of the FPGA and provide various quality metrics to ascertain the output image quality.

Section: Image Quality Assessmentmentioning

confidence: 99%

Towards Ultrasound Everywhere: A Portable 3D Digital Back-End Capable of Zone and Compound Imaging

IEEE Trans. Biomed. Circuits Syst.

Zhang

Angiolini

et al. 2018

“…We have assessed and quantified in detail the image reconstruction quality of our system in [26], [28]. The assessment includes Point Spread Function (PSF) evaluation, numerical inaccuracy quantification, and statistical inaccuracy distribution within the volume.…”

Section: B Quality Assessmentmentioning

confidence: 99%

Inexpensive 1024-channel 3D telesonography system on FPGA

2017 IEEE Biomedical Circuits and Systems Conference (BioCAS)

Doy

Loureiro

et al. 2017

Self Cite

Volumetric ultrasound (US) is a very promising development of medical US imaging. An under-exploited advantage of volumetric US is the mitigation of the strict probe positioning constrains necessary to acquire 2D scans, potentially allowing the decoupling of US image acquisition and diagnosis. However, today's 3D US systems are large and beset by high power and cost requirements, making them only available in well-equipped hospitals. In this study, we propose the first telesonography-capable medical imaging system that supports up to 1024 channels, on par with the state of the art. As a first embodiment, we have implemented our design in a single development FPGA board of 26.7cm×14cm×0.16cm, with an estimated power consumption of 6.1 W. Moreover, we have equipped our platform with an automatic positioning module to help any operator defining the scan location, hence allowing for better remote diagnosis. Our design supports two types of data inputs: real-time via an optical connection and offline over Ethernet. The reconstructed images can be visualized on an HDMI screen. The estimated cost of the proposed prototype materials is less than 4000e.

“…3(a)). In order to account for the elements that need to be discarded due to either the side lobes generated by the directivity of the piezoelectric transducer or the inaccuracy introduced by the approximated delays, a trimmed apodization scheme has been designed [4]. The proposed apodization is tighter than usual, which minimizes the inaccuracy due to delay approximations while not affecting image quality severely.…”

mentioning

confidence: 99%

Demo: Efficient delay and apodization for on-FPGA 3D ultrasound

Yüzügüler

Simon

2016 Conference on Design and Architectures for Signal and Image Processing (DASIP)

et al. 2016

Self Cite

In medical diagnosis, ultrasound (US) imaging is one of the most common, safe, and powerful techniques. Volumetric (3D) US is potentially very attractive, compared to 2D US, because it might enable telesonography -decoupling the local image acquisition, by an untrained person, and the diagnosis, by the trained sonographer, who can be remote. Unfortunately, current 3D systems are hospital-oriented, bulky and expensive, and they cannot be available in emergency operations or rural areas. This motivates us to develop a portable US platform with cheap, battery-operated, more efficient electronics.The core of any US imaging system is the beamforming (BF), which is the most computationally challenging and materially expensive step. BF consists of delay calculation and apodization. For each volume location, to identify whether it comprises fully reflective (white voxel) or non-reflective (black voxel) tissue, it is first necessary to compute the twoway traveling delay of the sound wave from the sound origin to this location and back to each piezoelectric element on the transducer. Apodization is a weighting used to eliminate side lobes arising due to the transducer's directivity function. Typically, apodization can be performed with a Hanning function, whose bell profile smoothly attenuates sensitivity towards the transducer edges. The width of the apodization profile can also expand with the imaging depth, optimizing resolution and minimizing clutter at all depths. Different systems, either commercial or research-based [1], have dealt with the processing demands of 3D BF by reducing the number of receive channels, which simplifies computation, but sacrifices resolution. To date, there is no satisfactory answer for a portable, low-power, low cost 3D US imaging system that still has the capability to process high-channel-count, or even full-resolution, probe readouts, for better resolution and contrast.We have previously proposed an approach [2] to more efficiently calculate delays. Instead of attempting to compute trillions of square roots per second, this method simply calculates a small reference set of delays (a few square roots produced by a Xilinx CORDIC IP), followed by, leveraging geometric considerations, the application of two additions per delay sample. In this paper we show a scalable beamformer architecture capable of supporting over 1024 transducer elements in a single, latest-generation FPGA. Fig. 1 shows the whole FPGA system including our beamformer custom block. The latter communicates via an AXI interface. The overall system includes a MicroBlaze processor subsystem and an Ethernet interface that is presently used for all I/O. The proposed architecture of the beamformer is shown in Fig. 2. Table I shows results of the proposed beamformer architecture including the resource utilization for reconstructing a 2.5M-voxel volume, using 4MHz center frequency, and 32MHz sampling frequency, supporting a 32×32 elements probe. The results show that a theoretical reconstruction rate of 50 volumes/s can be...