Ultrasound research scanner for real-time synthetic aperture data acquisition

Jensen, Jørgen Arendt; Holm, Olle; Jerisen, L.J.; Bendsen, H.; Nikolov, Svetoslav Ivanov; Tomov, Borislav Gueorguiev; Munk, Peter; Hansen, Martin; Salomonsen, K.; Hansen, Jens Munk; Gormsen, K.; Pedersen, Heidi Frølund; Gammelmark, Kim

doi:10.1109/tuffc.2005.1503974

Cited by 160 publications

(99 citation statements)

References 28 publications

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“…Then the central computer calculates the many beams that could be produced within the broad transmitted beam [22][23][24]. This is very much like the multi-line processing described earlier, except that the beam formation is done by a programmable computer instead of dedicated beamforming hardware.…”

Section: Synthetic Aperturementioning

confidence: 99%

Medical ultrasound systems

Powers

Kremkau

2011

Interface Focus.

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Medical ultrasound imaging has advanced dramatically since its introduction only a few decades ago. This paper provides a short historical background, and then briefly describes many of the system features and concepts required in a modern commercial ultrasound system. The topics addressed include array beam formation, steering and focusing; array and matrix transducers; echo image formation; tissue harmonic imaging; speckle reduction through frequency and spatial compounding, and image processing; tissue aberration; Doppler flow detection; and system architectures. It then describes some of the more practical aspects of ultrasound system design necessary to be taken into account for today's marketplace. It finally discusses the recent explosion of portable and handheld devices and their potential to expand the clinical footprint of ultrasound into regions of the world where medical care is practically non-existent. Throughout the article reference is made to ways in which ultrasound imaging has benefited from advances in the commercial electronics industry. It is meant to be an overview of the field as an introduction to other more detailed papers in this special issue.

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Section: Synthetic Aperturementioning

confidence: 99%

Medical ultrasound systems

Powers

Kremkau

2011

Interface Focus.

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“…RASMUS is an abbreviation for Remotely Accessible Software configurable Multi-channel Ultrasound Sampling system, and was designed as a very flexible US system capable of transmitting arbitrary waveforms and storage of raw array channel data. A more detailed description is found in [9]. The transducer used is a convex array with a stepping motor to allow for a continuous back and forth rocking motion.…”

Section: Measurement Setupmentioning

confidence: 99%

Rocking convex array used for 3D synthetic aperture focusing

Andresen

Nikolov²,

Pedersen

et al. 2008

2008 IEEE Ultrasonics Symposium

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Abstract-Volumetric imaging can be performed using 1D arrays in combination with mechanical motion. Outside the elevation focus of the array, the resolution and contrast quickly degrade compared to the azimuth plane, because of the fixed transducer focus. The purpose of this paper is to use synthetic aperture focusing (SAF) for enhancing the elevation focusing for a convex rocking array, to obtain a more isotropic point spread function.This paper presents further development of the SAF method, which can be used with curved array combined with a rocking motion. The method uses a virtual source (VS) for defocused multi-element transmit, and another VS in the elevation focus point. This allows a direct time-of-flight (ToF) to be calculated for a given 3D point. The method is evaluated using simulations from Field II and by measurements using the RASMUS experimental scanner with a 4.5 MHz convex array (GE Kretztechnik, Zipf, Austria). The array has an elevation focus at 60 mm of depth, and the angular rocking velocity is up to 140• /s. The scan sequence uses an f prf of 4500 -7000 Hz allowing up to 15 cm of penetration. The full width at half max (FWHM) and main-lobe to side-lobe ratio (MLSL) is used as quantitative measurements.The elevation FWHM for simulated scatterers placed at depths of 30 to 140 mm of depth were improved by 26.4% on average, and the MLSL ratio was improved by an average of 8.49 dB for the scatterers using 3D SA focusing. The elevation FWHM for a measured wire phantom was improved by 33.8% on average by applying 3D SA focusing. In-Vivo measurements show an improvement in C-scans matching what is found in simulations and wire phantoms.The method has shown the ability to improve the elevation focus and contrast for a convex rocking array. This was shown for simulations and for phantom and In-Vivo measurements using commercially available equipment.

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“…The data acquisition was performed using a 128 element linear array transducer and the RASMUS multi-channel sampling system [7]. This system can emit arbitrary waveforms on 128 elements, and sample 64 transducer elements in realtime.…”

Section: Simultaneous Sampling Of Multiple Cfm Linesmentioning

confidence: 99%

12B-6 Multi-Frequency Encoding for Rapid Color Flow and Quadroplex Imaging

Oddershede

Gran

Jensen

2007

2007 IEEE Ultrasonics Symposium Proceedings

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Abstract-Ultrasonic color flow maps are made by estimating the velocities line by line over the region of interest. For each velocity estimate, multiple repetitions are needed. This sets a limit on the frame rate, which becomes increasingly severe when imaging deeper lying structures or when simultaneously acquiring spectrogram data for triplex imaging. This paper proposes a method for decreasing the data acquisition time by simultaneously sampling multiple lines at different spatial positions for the color flow map using narrow band signals with disjoint spectral support. The signals are separated in the receiver by filters matched to the emitted waveforms and the autocorrelation estimator is applied. Alternatively, one spectral band can be used for creating a color flow map, while data for a number of spectrograms are acquired simultaneously. Using three disjoint spectral bands, this will result in a multi-frequency quadroplex imaging mode featuring a color flow map and two spectrograms at the same frame rate as a normal color flow map. The method is presented, various side-effects are considered, and the method is tested on data from a re-circulating flow phantom where a constant parabolic flow with a peak of 0.1 m/s is generated with a flow angle of 60 degrees. A commercial linear array transducer is used and data are sampled using our RASMUS multi-channel sampling system. An in-vivo multifrequency quadroplex movie of the common carotid artery of a healthy male volunteer was created.The flow phantom measurements gave a mean standard deviation across the flow profile of 3.1%, 2.5%, and 2.1% of the peak velocity for bands at 5 MHz, 7 MHz, and 9 MHz, respectively. The in-vivo multi-frequency quadroplex movie showed the color flow map, and the two independent spectrograms at different spatial positions. This enables studying the flow over an arterial stenosis by simultaneously acquiring spectrograms on both sides of the stenosis, while maintaining the color flow map. A frame rate of 21.4 frames per second was achieved in this in-vivo experiment.

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Ultrasound research scanner for real-time synthetic aperture data acquisition

Cited by 160 publications

References 28 publications

Medical ultrasound systems

Medical ultrasound systems

Rocking convex array used for 3D synthetic aperture focusing

12B-6 Multi-Frequency Encoding for Rapid Color Flow and Quadroplex Imaging

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