Sparse geometries for two-dimensional array transducers in volumetric imaging

Davidsen, R.E.; Smith, Stephen W.

doi:10.1109/ultsym.1993.339598

Cited by 19 publications

(14 citation statements)

References 9 publications

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“…Sparse arrays have been proposed in the field of ultrasonics for both active (Turnbull & Foster, 1991; Davidsen & Smith, 1993; Lockwood & Foster, 1996) and passive (Coviello, et al, 2012) (O'Reilly, et al, 2014; Jones, et al, 2015) imaging, as well as for FUS therapy (Hynynen & Jones, 2016). In the current device, the transducer elements were randomly placed on a hemispherical shell in a configuration that was optimized through numerical simulations (Jones, et al, 2013), since grating lobes (on both transmit and receive) resulting from periodic, sparse arrangements can be suppressed by using an irregular layout (Goss, et al, 1996; Hutchinson, et al, 1996; Hand, et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

A multi-frequency sparse hemispherical ultrasound phased array for microbubble-mediated transcranial therapy and simultaneous cavitation mapping

et al. 2016

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Focused ultrasound (FUS) phased arrays show promise for non-invasive brain therapy. However, the majority of them are limited to a single transmit/receive frequency and therefore lack the versatility to expose and monitor the treatment volume. Multi-frequency arrays could offer variable transmit focal sizes under a fixed aperture, and detect different spectral content on receive for imaging purposes. Here, a three-frequency (306, 612 and 1224 kHz) sparse hemispherical ultrasound phased array (31.8 cm aperture; 128 transducer modules) was constructed and evaluated for microbubble-mediated transcranial therapy and simultaneous cavitation mapping. The array is able to perform effective electronic beam steering over a volume spanning [−40, 40] and [−30, 50] mm in the lateral and axial directions, respectively. The focal size at the geometric center is approximately 0.9 (2.1) mm, 1.7 (3.9) mm, and 3.1 (6.5) mm in lateral (axial) pressure full width at half maximum (FWHM) at 1224, 612, and 306 kHz, respectively. The array was also found capable of dual-frequency excitation and simultaneous multi–foci sonication, which enables the future exploration of more complex exposure strategies. Passive acoustic mapping of dilute microbubble clouds demonstrated that the point spread function of the receive array has a lateral (axial) intensity FWHM between 0.8-3.5 mm (1.7-11.7 mm) over a volume spanning [−25, 25] mm in both the lateral and axial directions, depending on the transmit/receive frequency combination and the imaging location. The device enabled both half and second harmonic imaging through the intact skull, which may be useful for improving the contrast-to-tissue ratio or imaging resolution, respectively. Preliminary in-vivo experiments demonstrated the system's ability to induce blood-brain barrier opening and simultaneously spatially map microbubble cavitation activity in a rat model. This work presents a tool to investigate optimal strategies for non-thermal FUS brain therapy and concurrent microbubble cavitation monitoring through the availability of multiple frequencies.

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Section: Discussionmentioning

confidence: 99%

A multi-frequency sparse hemispherical ultrasound phased array for microbubble-mediated transcranial therapy and simultaneous cavitation mapping

et al. 2016

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“…, n is an integer that is ¢ 0, the subscript ''J n '' potential applications of these beams to real-time volumetric immeans ''nth-order Bessel beams,'' J n (r) is the nth-order Bessel aging [62][63][64][65][66][67] …”

Section: Limited Diffraction Beams Have An Infinite Depth Of Field Ifmentioning

confidence: 99%

“…Because the speed of sound in objects such as biologic soft tissues is finite, the image frame rate of conventional B-mode scanners is limited, especially when imaging a large region of interest. In formed [62,63] or a simultaneous transmission of multiple foreceiving beams will increase image frame rate. Because grid array cused beams to cover the area.…”

Section: Possible Applicationsmentioning

confidence: 99%

Limited diffraction array beams

Liu

1997

Int. J. Imaging Syst. Technol.

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Limited diffraction beams have a large depth of field infinite aperture. Because of their high side lobes and complex and could have many applications. In this article, new limited diffracbeam patterns near the cone surface, these devices are not curtion beams are developed. They are composed of multiple parallel rently used in clinics. Ring antenna [42] or transducer [43,44] is beams and are thus called array beams. A broadband synthetic array another type of device that increases the depth of field. However, experiment is used to produce these beams of a finite aperture, and the depth of field is increased only in the far field of the rings results are in excellent agreement with theory over a large depth of [45,46] where beams diffract significantly. Near the surfaces of field. In addition, potential applications of the new beams to real-time the rings, beams do not even have a central peak. In addition, volumetric imaging and measurement of transverse velocity of blood ring devices have a low energy efficiency because they must be flow are described.

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“…Additionally, a system capturing a two-dimensional image at a rate of 20 fps would take over 25s to capture a volume of the same resolution and field of view because of the need to wait for one pulse to return before sending the next. Sparse arrays and signal reducing ASICs have been introduced to mitigate these challenges [4], [5], but revisiting the method of volumetric capture can offer more efficient use of each pulse event to accomplish full volume imaging in real-time.…”

Section: Introductionmentioning

confidence: 99%

Crossed-array transducer for real-time 3D imaging

Joyce

Lockwood

2014

2014 IEEE International Ultrasonics Symposium

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A crossed-array transducer for real-time threedimensional imaging has been developed along with an accompanying transmit pulser and beamforming system. The system incorporates novel design features that address the unique constraints and requirements imposed by the crossedarray construction. These developments include a 1-3 composite with radially apodized polarization; a bipolar ±100V pulser with variable frequency and delay control, and a low-impedance ground in the off-state; and a transmit beamformer with a computer interface to monitor and control the system. Experimental results demonstrate the system to have a 3dB beamwidth of 2mm at 60mm depth (f/1.4) and 4mm at 80mm depth (f/1.8). The beam-shape has excellent confinement along the focused axis, and the defocused orthogonal plane reaches a maximum intensity drop of 6dB over a 45° sector.

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Sparse geometries for two-dimensional array transducers in volumetric imaging

Cited by 19 publications

References 9 publications

A multi-frequency sparse hemispherical ultrasound phased array for microbubble-mediated transcranial therapy and simultaneous cavitation mapping

A multi-frequency sparse hemispherical ultrasound phased array for microbubble-mediated transcranial therapy and simultaneous cavitation mapping

Limited diffraction array beams

Crossed-array transducer for real-time 3D imaging

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