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Wayne Kreider

Senior Engineer

Email

wkreider@u.washington.edu

Phone

206-897-1814

Education

Bachelor of Science Engineering Science & Mechanics, Virginia Tech, 1993

Master of Science Engineering Mechanics, Virginia Tech, 1995

Doctor of Philosophy Bioengineering, University of Washington, 2008

Publications

2000-present and while at APL-UW

The role of trapped bubbles in kidney stone detection with the color Doppler ultrasound twinkling artifact

Simon, J.C., O.A. Sapozhnikov, W. Kreider, M. Breshock, J.C. Williams Jr., and M.R. Bailey, "The role of trapped bubbles in kidney stone detection with the color Doppler ultrasound twinkling artifact," Phys. Med. Biol., 63, 025011, doi:10.1088/1361-6560/aa9a2f, 2018.

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9 Jan 2018

The color Doppler ultrasound twinkling artifact, which highlights kidney stones with rapidly changing color, has the potential to improve stone detection; however, its inconsistent appearance has limited its clinical utility. Recently, it was proposed stable crevice bubbles on the kidney stone surface cause twinkling; however, the hypothesis is not fully accepted because the bubbles have not been directly observed. In this paper, the micron or submicron-sized bubbles predicted by the crevice bubble hypothesis are enlarged in kidney stones of five primary compositions by exposure to acoustic rarefaction pulses or hypobaric static pressures in order to simultaneously capture their appearance by high-speed photography and ultrasound imaging. On filming stones that twinkle, consecutive rarefaction pulses from a lithotripter caused some bubbles to reproducibly grow from specific locations on the stone surface, suggesting the presence of pre-existing crevice bubbles. Hyperbaric and hypobaric static pressures were found to modify the twinkling artifact; however, the simple expectation that hyperbaric exposures reduce and hypobaric pressures increase twinkling by shrinking and enlarging bubbles, respectively, largely held for rough-surfaced stones but was inadequate for smoother stones. Twinkling was found to increase or decrease in response to elevated static pressure on smooth stones, perhaps because of the compression of internal voids. These results support the crevice bubble hypothesis of twinkling and suggest the kidney stone crevices that give rise to the twinkling phenomenon may be internal as well as external.

Design and characterization of a 2-dimensional focused 1.5-MHz ultrasound array with a compact spiral arrangement of 256 circular elements

Sapozhnikov, O., M. Ghanem, A. Maxwell, P. Rosnitskiy, P. Yuldashev, W. Kreider, B. Cunitz, M. Bailey, and V. Khokhlova, "Design and characterization of a 2-dimensional focused 1.5-MHz ultrasound array with a compact spiral arrangement of 256 circular elements," Proc., IEEE International Ultrasonics Symposium, 6-9 September, Washington, D.C., doi:10.1109/ULTSYM.2017.8092165 (IEEE, 2017).

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2 Nov 2017

Multi-element ultrasound arrays are increasingly used in clinical practice for both imaging and therapy. In therapy, they allow electronic steering, aberration correction, and focusing. To avoid grating lobes, an important requirement for such an array is the absence of periodicity in the arrangement of the elements. A convenient solution is the arrangement of the elements along spirals. The objective of this work was to design, fabricate, and characterize an array for boiling histotripsy applications that is capable of generating shock waves in the focus of up to 100 MPa peak pressure while having a reasonable electronic steering range.

Design and characterization of a research phantom for shock-wave enhanced irradiations in high intensity focused ultrasound therapy

Kreider, W., B. Dunmire, J. Kucewicz, C. Hunter, T. Khokhlova, G. Schade, A. Maxwell, O. Sapozhnikov, L. Crum, and V. Khokhlova, "Design and characterization of a research phantom for shock-wave enhanced irradiations in high intensity focused ultrasound therapy," Proc., IEEE International Ultrasonics Symposium, 6-9 September, Washington, D.C., doi:10.1109/ULTSYM.2017.8092866 (IEEE, 2017).

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2 Nov 2017

The use of shock waves for enhancing thermal effects and mechanically ablating tissue is gaining increased attention in high intensity focused ultrasound (HIFU) applications such as tumor treatment, drug delivery, noninvasive biopsy, and immunotherapy. For abdominal targets, the presence of ribs and inhomogeneous adipose tissue can affect shock formation through aberration, absorption, and diffraction. The goal of this study was to design and validate a phantom for investigating the impact of different tissue structures on shock formation in situ. A transducer with driving electronics was developed to operate at 1.2 MHz with the ability to deliver either short pulses at high powers (up to 5 kW electric power) or continuous output at moderate powers (up to 700 W). Fat and muscle layers were represented by phantoms made from polyvinyl alcohol. Ribs were 3D-printed from a photopolymer material based on 3D CT scan images. Representative targeted tissue was comprised of optically transparent alginate or polyacrylamide gels. The system was characterized by hydrophone measurements free-field in water and in the presence of a body wall or rib phantoms. Shocked waveforms with peak positive/negative pressures of +100 / –20 MPa were measured at the focus in a free field at 1 kW electric source power. When ribs were present, shocks formed at about 50% amplitude at the same power, and higher pressures were measured with ribs positioned closer to the transducer. A uniform body wall structure attenuated shock amplitudes by a smaller amount than non-uniform, and the measurements were insensitive to the axial position of the phantom. Signal magnitude loss at the focus for both the rib phantoms and abdominal wall tissue were consistent with results from real tissues. In addition, boiling histotripsy lesions were generated and visualized in the target gels. The results demonstrate that the presence of ribs and absorptive tissue-mimicking layers do not prevent shock formation at the focus. With real-time lesion visualization, the phantom is suitable for adaptation as a training tool.

More Publications

Inventions

Methods and Systems for Non-invasive Treatment of Tissue Using High Intensity Focused Ultrasound Therapy

Patent Number: 9,700,742

Michael Canney, Mike Bailey, Larry Crum, Joo Ha Hwang, Tatiana Khokhlova, Vera Khokhlova, Wayne Kreider, Oleg Sapozhnikov

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Patent

11 Jul 2017

Methods and systems for non-invasive treatment of tissue using high intensity focused ultrasound ("HIFU") therapy. A method of non-invasively treating tissue in accordance with an embodiment of the present technology, for example, can include positioning a focal plane of an ultrasound source at a target site in tissue. The ultrasound source can be configured to emit HIFU waves. The method can further include pulsing ultrasound energy from the ultrasound source toward the target site, and generating shock waves in the tissue to induce boiling of the tissue at the target site within milliseconds. The boiling of the tissue at least substantially emulsifies the tissue.

Portable Acoustic Holography Systems for Therapeutic Ultrasound Sources and Associated Devices and Methods

Patent Number: 9,588,491

Oleg Sapozhnikov, Mike Bailey, Vera Khokhlova, Wayne Kreider

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Patent

7 Mar 2017

The present technology relates generally to portable acoustic holography systems for therapeutic ultrasound sources, and associated devices and methods. In some embodiments, a method of characterizing an ultrasound source by acoustic holography includes the use of a transducer geometry characteristic, a transducer operation characteristic, and a holography system measurement characteristic. A control computer can be instructed to determine holography measurement parameters. Based on the holography measurement parameters, the method can include scanning a target surface to obtain a hologram. Waveform measurements at a plurality of points on the target surface can be captured. Finally, the method can include processing the measurements to reconstruct at least one characteristic of the ultrasound source.

MRI-Guided Lithotripsy of Urinary Tract Stones

Record of Invention Number: 47984

Mike Bailey, Wayne Kreider, Adam Maxwell, Yak-Nam Wang

Disclosure

23 Feb 2017

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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