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Passive cavitation imaging with ultrasound arrays
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10.1121/1.3238260
/content/asa/journal/jasa/126/6/10.1121/1.3238260
http://aip.metastore.ingenta.com/content/asa/journal/jasa/126/6/10.1121/1.3238260
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Computer simulations for passive images created using 64-element (14.08 mm) subapertures are shown here. The top row contains examples of simulations where an “idealized” array approximation is used for each subaperture, with single point-sources at depths (a) 20 mm, (b) 55 mm, (c) and 90 mm. Simulated images in the bottom row were created through time-delay focusing at 16 equally spaced depths (6.2 mm) with single point-sources located at (d) 20 mm, (e) 55 mm (e), and (f) 90 mm. All images are plotted with a 40 dB dynamic range.

Image of FIG. 2.
FIG. 2.

Computer simulations for passive images created using a constant -number (7.1) subaperture are shown here. Except for the subaperture sizes, images were created using the same simulation methods, focus positions, and source locations as the corresponding panels in Fig. 1.

Image of FIG. 3.
FIG. 3.

Point-sources represented in this figure were assumed to emit acoustic energy between 6.3 and 6.7 MHz (64-element subapertures). (a) Simulated image of five point-sources at (azimuth mm, range mm): (−12,40), (−10,40), (0, 10), (0, 40), (0, 70). (b) Simulated image of a cluster of 25 point-sources placed randomly in the image plane between −7 and −3 mm in azimuth, and 3141 mm in depth. (c) Comparison between depth-integrated simulated image brightness as a function of azimuth, and the azimuthal distribution of point-sources. (d) Comparison between azimuth-integrated simulated image brightness as a function of range, and the range distribution of point-sources. Passive cavitation images are plotted with a 40 dB dynamic range.

Image of FIG. 4.
FIG. 4.

Experimental setup: CW ultrasound sources sonicate a 1-mm steel wire, PBS and bovine liver, while a 192-element linear array captures passive images.

Image of FIG. 5.
FIG. 5.

(a) Passive images of 520-kHz ultrasound scattered from a 1-mm steel wire located at 20-mm depth, (b) 55 mm and (c) 90 mm. A constant -number (7.1) subaperture was employed. Energy in the source harmonics (5.2–9.36 MHz) was integrated. Passive cavitation images are plotted with a 40 dB dynamic range.

Image of FIG. 6.
FIG. 6.

Image magnitude along the array axis, plotted with respect to the range dimension, for representative simulation (---) and experiment (—) cases. The depth location of simulated point-sources and wire target (in experiment) were (a) 20 mm, (b) 55 mm, and (c) 90 mm.

Image of FIG. 7.
FIG. 7.

Acoustic emission spectra from PBS solution sonicated with 520-kHz, cw ultrasound at 0.125 MPa (peak-negative pressure). Power spectra measured in dB relative to the measured noise floors were computed from (a) rf data acquired by the L7 array and (b) acoustic emission signals recorded by the single-element (10 MHz) detector.

Image of FIG. 8.
FIG. 8.

Representative passive cavitation images in saline solution due to 520-kHz CW ultrasound 0–0.15 MPa (peak-negative): (a) B-scan showing a cavitating bubble cloud, (b) co-registered passive cavitation image formed from ultrahar-monic emissions (6.5 MHz), and (c) co-registered passive cavitation image formed from broadband emissions (6.3–6.7 MHz). (d) Comparison between B-scan and passive image brightness levels integrated between 31 and 41-mm depth, across all azimuths. Passive cavitation images are plotted with a 30 dB dynamic range.

Image of FIG. 9.
FIG. 9.

(a) Representative passive cavitation image using broadband emissions (8–10 MHz) from bovine liver sonicated with 2.2-MHz, CW, focused ultrasound at 0.8 MPa peak-to-peak pressure amplitude (0.38 MPa peak-negative pressure). (b) Spatially integrated emission energy as a function of sonication amplitude, plotted as mean ± st. dev. (c) Comparison of emission amplitude at 20-mm depth with measured beam profile at 0.80 MPa (peak to peak) sonication pressure. (d) Comparison of emission amplitude at 20-mm depth with measured beam profile at 1.44 MPa (peak to peak) sonication pressure. Passive cavitation images are plotted with a 40 dB dynamic range.

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/content/asa/journal/jasa/126/6/10.1121/1.3238260
2009-12-14
2014-04-20
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Passive cavitation imaging with ultrasound arrays
http://aip.metastore.ingenta.com/content/asa/journal/jasa/126/6/10.1121/1.3238260
10.1121/1.3238260
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