Beamforming of sound from two-dimensional arrays using spatial matched filters

Yen, Jeannette

doi:10.1121/1.4821988

Cited by 15 publications

(13 citation statements)

References 25 publications

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“…A modified delay-and-sum (DAS) beamformer using the methods described in [11] is employed, where the size of the line elements are taken into account. The second beamformer uses the spatial matched filter (SMF) [24]- [26] methods for processing the RF data. Here the received signals are modeled in Field II and the signal shape is used as a spatial matched filter in the beamformation [24].…”

Section: Introductionmentioning

confidence: 99%

Imaging Performance for Two Row–Column Arrays

Bouzari

Engholm

Nikolov

et al. 2019

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

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This study evaluates the volumetric imaging performance of two prototyped 62+62 row-column-addressed (RCA) 2-D array transducer probes using three Synthetic Aperture Imaging (SAI) emission sequences and two different beamsformers. The probes are fabricated using capacitive micromachined ultrasonic transducer (CMUT), and piezoelectric transducer (PZT) technology. Both have integrated apodization to reduce ghost echoes and are designed with similar acoustical features i.e., 3 MHz center frequency, λ /2-pitch, and 24.8×24.8 mm 2 active footprint. Raw RF data are obtained using an experimental research ultrasound scanner, SARUS. The SAI sequences are designed for imaging down to 14 cm at a volume rate of 88 Hz. Two beamforming methods: Spatial matched filtering and rowcolumn adapted delay-and-sum are used for beamforming the RF data. The imaging quality is investigated through simulations and phantom measurements. Both probes on average have similar lateral full-width at half-maximum (FWHM) values, but the PZT probe has 20% smaller cystic resolution values and 70% larger contrast-to-noise ratio compared to the CMUT probe. The CMUT probe can penetrate down to 15 cm, and the PZT probe down to 30 cm. The CMUT probe has 17% smaller axial FWHM values. The matched filter focusing shows and improved B-mode image for measurements on a cyst phantom with an improved speckle pattern and better visualization of deeper lying cysts. The results of this study demonstrate the potentials of RCA 2-D arrays against fully addressed 2-D arrays, which are low channel count (e.g. 124 instead of 3,844), low acoustic intensity (MI ≤0.88 and I spta ≤5.5 mW/cm 2 ), and high penetration depth (down to 30 cm), which makes 3-D imaging at high volume rates possible with equipment in the price range of conventional 2-D imaging.

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Section: Introductionmentioning

confidence: 99%

Imaging Performance for Two Row–Column Arrays

Bouzari

Engholm

Nikolov

et al. 2019

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

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“…Spatial matched filter (SMF) beamforming is an algorithm, in which the impulse responses in transmission and in reception are considered for every point, unlike the DAS which assumes the impulse responses to be like delta functions [4], [8], [9]. Due to acoustically equivalent line-elements via row-column addressing the 2-D matrix array, SMF has the potential to improve the spatial resolution and the SNR.…”

Section: Introductionmentioning

confidence: 99%

“…Due to acoustically equivalent line-elements via row-column addressing the 2-D matrix array, SMF has the potential to improve the spatial resolution and the SNR. In [4], based on simulations, it was shown that SMF beamforming provides comparable results like synthetic aperture imaging with DAS beamforming. However this paper investigates SMF beamforming using synthetic aperture imaging.…”

Section: Introductionmentioning

confidence: 99%

Volumetric ultrasound imaging with row-column addressed 2-D arrays using Spatial Matched Filter beamforming

Bouzari

Engholm

Christiansen

et al. 2015

2015 IEEE International Ultrasonics Symposium (IUS)

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Abstract-For 3-D ultrasound imaging with row-column addressed 2-D arrays, the two orthogonal 1-D transmit and receive arrays are both used for one-way focusing in the lateral and elevation directions separately and since they are not in the same plane, the two-way focusing is the same as one-way focusing. However, the achievable spatial resolution and contrast of the B-mode images in Delay and Sum (DAS) beamforming are limited by the aperture size and by the operating frequency. This paper, investigates Spatial Matched Filter (SMF) beamforming on row-column addressed 2-D arrays to increase spatial resolution. The performance is investigated on both simulated and experimentally collected 3-D data by comparing the Point Spread Functions (PSFs) and the phantom images obtained with standard DAS and with SMF. Results show that the SMF beamformer outperforms DAS in both simulated and experimental trials and that a higher contrast resolution can be achieved by SMF beamforming (i.e., narrower main lobe and lower side lobes). The 6dB, 20dB and 40dB cystic resolution for a DAS simulated PSF at (0,0,30)mm are 1.22mm, 3.54mm and 7.46mm, for SMF beamforming they are 1.11mm, 2.33mm and 5.42mm accordingly. For measured RF-data of an iron needle facing toward the transducer positioned at (0,0,32.5)mm along the central axis, the 6dB, 20dB and 40dB cystic resolution for DAS beamforming are 1.99mm, 2.19mm and 4.26mm, and they are 0.8mm, 2.06mm and 4.18mm for SMF beamforming accordingly. SMF beamforming increases the contrast resolution which turns into a better quality of the B-mode images.

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“…different techniques to improve the resolution, sensitivity, or frame rate of row-column-addressed arrays were explored theoretically by daher et al [11], [12] and yen [13] using synthetic aperture techniques and spatial matched filters. recently, rasmussen and Jensen used a fully addressed 32 × 32 array in a measurement study to compare the imaging performance of a fully addressed array to that of a row-column-addressed array [14].…”

mentioning

confidence: 99%

3-D imaging using row–column-addressed arrays with integrated apodization— part ii: transducer fabrication and experimental results

Christiansen

Rasmussen

Bagge³

et al. 2015

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

105

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This paper demonstrates the fabrication, characterization, and experimental imaging results of a 62+62 element λ/2-pitch row-column-addressed capacitive micromachined ultrasonic transducer (CMUT) array with integrated apodization. A new fabrication process was used to manufacture a 26.3 mm by 26.3 mm array using five lithography steps. The array includes an integrated apodization, presented in detail in Part I of this paper, which is designed to reduce the amplitude of the ghost echoes that are otherwise prominent for row-column-addressed arrays. Custom front-end electronics were produced with the capability of transmitting and receiving on all elements, and the option of disabling the integrated apodization. The center frequency and -6-dB fractional bandwidth of the array elements were 2.77 ± 0.26 MHz and 102 ± 10%, respectively. The surface transmit pressure at 2.5 MHz was 590 ± 73 kPa, and the sensitivity was 0.299 ± 0.090 V/Pa. The nearest neighbor crosstalk level was -23.9 ± 3.7 dB, while the transmit-to-receive-elements crosstalk level was -40.2 ± 3.5 dB. Imaging of a 0.3-mm-diameter steel wire using synthetic transmit focusing with 62 single-element emissions demonstrated axial and lateral FWHMs of 0.71 mm and 1.79 mm (f-number: 1.4), respectively, compared with simulated axial and lateral FWHMs of 0.69 mm and 1.76 mm. The dominant ghost echo was reduced by 15.8 dB in measurements using the integrated apodization compared with the disabled configuration. The effect was reproduced in simulations, showing a ghost echo reduction of 18.9 dB.

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Beamforming of sound from two-dimensional arrays using spatial matched filters

Cited by 15 publications

References 25 publications

Imaging Performance for Two Row–Column Arrays

Imaging Performance for Two Row–Column Arrays

Volumetric ultrasound imaging with row-column addressed 2-D arrays using Spatial Matched Filter beamforming

3-D imaging using row–column-addressed arrays with integrated apodization— part ii: transducer fabrication and experimental results

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