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Bryan Cunitz

Engineer IV

Email

bwc@apl.washington.edu

Phone

206-543-6804

Education

B.A. Physics, Colby College, 1999

B.S. Engineering, Dartmouth College, 2000

M.S. Electrical Engineering, University of Washington, 2005

Videos

Burst Wave Lithotripsy: An Experimental Method to Fragment Kidney Stones

CIMU researchers are investigating a noninvasive method to fragment kidney stones using ultrasound pulses rather than shock waves. Consecutive acoustic cycles accumulate and concentrate energy within the stone. The technique can be 'tuned' to create small fragments, potentially improving the success rate of lithotripsy procedures.

20 Nov 2014

Ultrasonic Detection and Propulsion of Kidney Stones

An ultrasound-based system assembled from commercial components and customized software control locates kidney stones, applies an acoustic radiative force, and repositions the stones so they are more likely to pass naturally. Watch urologist test the system.

2 May 2013

SonoMotion: A Budding Start-up Company

A research team has developed new technologies to treat kidney stone disease with an ultrasound-based system. Embraced by clinicians, their advances are now being taken to the next step: transition the prototype to an approved device that will roll into hospitals and clinics around the world.

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11 Feb 2013

At the Center for Industrial and Medical Ultrasound a team of scientists, engineers, and students has developed an ultrasound-based system that may provide an office procedure to speed the natural passage of kidney stones. The system uses commercial ultrasound components to locate stones in kidneys. It creates clear pictures of them and then applies an acoustic radiative force, repositioning stones in the kidney so they are more likely to pass naturally.

As a research team, considerable technical advancements have been made and valuable feedback and cooperation has been garnered from the user community – the clinicians. The scientists, engineers, urologists, and commercialization experts are now collaborating to take the next steps.

SonoMotion has partnered with a hardware manufacturing company and licensed the ultrasonic propulsion of kidney stones technology with the University of Washington. The next big step will be to transition the prototype system into one that will pass the rigors of FDA review and be ready to roll into hospitals and clinics around the world.

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Publications

2000-present and while at APL-UW

Field characterization and compensation of vibrational nonuniformity for a 256-element focused ultrasound phased array

Ghanem, M.A., A.D. Maxwell, W. Kreider, B.W. Cunitz, V.A. Khokhlova, O.A. Sapozhnikov, and M.R. Bailey, "Field characterization and compensation of vibrational nonuniformity for a 256-element focused ultrasound phased array," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 65, 1618-1630, doi:10.1109/TUFFC.2018.2851188, 2018.

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1 Sep 2018

Multielement focused ultrasound phased arrays have been used in therapeutic applications to treat large tissue volumes by electronic steering of the focus, to target multiple simultaneous foci, and to correct aberration caused by inhomogeneous tissue pathways. There is an increasing interest in using arrays to generate more complex beam shapes and corresponding acoustic radiation force patterns for manipulation of particles such as kidney stones. Toward this end, experimental and computational tools are needed to enable accurate delivery of desired transducer vibrations and corresponding ultrasound fields. The purpose of this paper was to characterize the vibrations of a 256-element array at 1.5 MHz, implement strategies to compensate for variability, and test the ability to generate specified vortex beams that are relevant to particle manipulation. The characterization of the array output was performed in water using both element-by-element measurements at the focus of the array and holography measurements for which all the elements were excited simultaneously. Both methods were used to quantify each element’s output so that the power of each element could be equalized. Vortex beams generated using both compensation strategies were measured and compared to the Rayleigh integral simulations of fields generated by an idealized array based on the manufacturer’s specifications. Although both approaches improved beam axisymmetry, compensation based on holography measurements had half the error relative to the simulation results in comparison to the element-by-element method.

Combined burst wave lithotripsy and ultrasonic propulsion fo improved urinary stone fragmentation

Zwaschka, T.A., J.S. Ahn, B.W. Cunitz, M.R. Bailey, B. Dunmire, M.D. Sorensen, J.D. Harper, and A.D. Maxwell, "Combined burst wave lithotripsy and ultrasonic propulsion fo improved urinary stone fragmentation," J. Endourol., 32, 344-349, doi:10.1089/end.2017.0675, 2018.

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1 Apr 2018

Purpose

Burst wave lithotripsy (BWL) is a new technology in development to fragment urinary stones. Ultrasonic propulsion (UP) is a separate technology under investigation for displacing stones. We measure the effect of propulsion pulses on stone fragmentation from BWL.

Materials and Methods

Two artificial stone models (crystalline calcite, BegoStone plaster) and human calcium oxalate monohydrate (COM) stones measuring 5 to 8 mm were subjected to ultrasound exposures in a polyvinyl chloride tissue phantom within a water bath. Stones were exposed to BWL with and without propulsion pulses interleaved for set time intervals depending on stone type. Fragmentation was measured as a fraction of the initial stone mass fragmented to pieces smaller than 2 mm.

Results

BegoStone model comminution improved from 6% to 35% (p < 0.001) between BWL and BWL with interleaved propulsion in a 10-minute exposure. Propulsion alone did not fragment stones, whereas addition of propulsion after BWL slightly improved BegoStone model comminution from 6% to 11% (p < 0.001). BegoStone model fragmentation increased with rate of propulsion pulses. Calcite stone fragmentation improved from 24% to 39% in 5 minutes (p = 0.047) and COM stones improved from 17% to 36% (p = 0.01) with interleaved propulsion.

Conclusions

BWL with UP improved stone fragmentation compared with BWL alone in vitro. The improvement was greatest when propulsion pulses are interleaved with BWL treatment and when propulsion pulses are applied at a higher rate. Thus, UP may be a useful adjunct to enhance fragmentation in lithotripsy in vivo.

PD37-09 kidney stone contrast with color-Doppler twinkling artifact as a function of mechanical index

Cunitz, B., J. Dai, M. Sorenson, R. Sweet, B. Dunmire, J. Thiel, M. Bruce, M. Bailey, Z. Liu, and J. Harper, "PD37-09 kidney stone contrast with color-Doppler twinkling artifact as a function of mechanical index," J. Urol., 199, e734, doi:10.1016/j.juro.2018.02.1744, 2018.

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1 Apr 2018

Kidney stones can exhibit a twinkling artifact under color-flow Doppler ultrasound. There has been much work that suggests the mechanism for this artifact is micron sized bubbles trapped in the cracks of the stone cavitating from the incident Doppler pulses. We hypothesize that the signal-to-clutter ratio (SCR) of stone-to-background in Doppler mode increases with the ultrasound mechanical index (MI), a metric of the likelihood of cavitation, and that a minimum MI is needed for visibility under Doppler.

Our results show the contrast ratio of the twinkling artifact on a kidney stone to background noise increases with the MI. This suggests that adjusting the system settings to increase the MI on the stone, such as lowering the frequency and increasing the amplitude, will improve stone contrast and the ability to detect a kidney stone. Additionally, ultrasound manufacturers can potentially implement a stone-specific imaging preset for Doppler that maximizes the MI of the output while remaining within the regulated safety limits.

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Inventions

Targeting Methods and Devices for Non-invasive Therapy Delivery

Record of Invention Number: 48305

Bryan Cunitz, Mike Bailey, Barbrina Dunmire, Michael Kennedy Hall, Adam Maxwell, Matthew Sorenson

Disclosure

11 Apr 2018

Pulse Amplifier for Driving Ultrasound Transducers

Patent Number: 9,867,999

Adam Maxwell, Bryan Cunitz, Mike Bailey, Vera Khokhlova, Timothy Hall

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Patent

16 Jan 2018

Embodiments of the invention include improved radiofrequency (RF) pulse amplifier systems that incorporate an energy array comprising multiple capacitors connected in parallel. The energy array extends the maximum length of pulses and the maximum achievable peak power output of the amplifier when compared to similar systems. Embodiments also include systems comprising the amplifier configured to drive a load, wherein the load may include one or more ultrasound (e.g., piezoelectric) transducers Related methods of using the amplifier are also provided.

Ultrasound Based Method and Apparatus for Stone Detection and to Facilitate Clearance Thereof

Patent Number: 9,597,103

Mike Bailey, John Kucewicz, Barbrina Dunmire, Neil Owen, Bryan Cunitz

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Patent

21 Mar 2017

Described herein are methods and apparatus for detecting stones by ultrasound, in which the ultrasound reflections from a stone are preferentially selected and accentuated relative to the ultrasound reflections from blood or tissue. Also described herein are methods and apparatus for applying pushing ultrasound to in vivo stones or other objects, to facilitate the removal of such in vivo objects.

More Inventions

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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