Researchers

Adam Maxwell

CIMU Department

APL-UW

Research Assistant Professor, Urology

Wayne Kreider

Senior Engineer

CIMU Department

APL-UW

Bryan Cunitz

Engineer IV

CIMU Department

APL-UW

Oleg Sapozhnikov

Senior Principal Engineer

CIMU Department

APL-UW

Vera Khokhlova

Senior Principal Engineer

CIMU Department

APL-UW

Mathew Sorensen

Assistant Professor

UW Deptartment of Urology

Jonathan Harper

Assistant Professor

UW Department of Urology

Mike Bailey

Senior Principal Engineer

CIMU Department

APL-UW

Associate Professor, Mechanical Engineering and Adjunct Assistant Professor, Urology

Madeline Hubbard

Student Researcher

UW Department of Civil Engineering

Christopher Hunter

Ultrasound Engineer

CIMU Department

APL-UW

Yak-Nam Wang

Senior Engineer

CIMU Department

APL-UW

Funding

National Institute of Diabetes and Digestive and Kidney Diseases

National Space Biomedical Research Institute

Collaborators

International Kidney Stone Institute

Computational Flow Physics Group

California Institute of Technology

Jonathan Freund

Professor, U. Illinois Urbana-Champaign

Burst Wave Lithotripsy

An Experimental Method to Fragment Kidney Stones

In many ways, this is a narrow bandwidth version of shock wave lithotripsy. Rather than hitting the stone with a hammer, it's a series of waves that enables the stone to be broken with more control and into uniform fragments.

So far, we found we can treat most stone types. We can treat some of them very rapidly.

We imagine there is going to be a range of sizes of stones we can break. We're trying to find the limits of what indications burst wave lithotripsy could be used for.

Effective, Noninvasive Fragmentation of Stones

Cloud Cavitation in Burst Wave Lithotripsy

The most common treatment for kidney stones is shock wave lithotripsy (SWL). SWL is a noninvasive procedure where shock waves are focused into the body and onto the stone, shattering it into small fragments that the patient will pass spontaneously. Because it is noninvasive, SWL is the treament most preferred by patients. Unfortunately, this procedure is unsuccessful about 40% of the time, and large residual stone fragments sometimes remain that require repeat treatments or alternative, more invasive methods of extraction.

Researchers at the Center for Industrial and Medical Ultrasound — CIMU — have been performing SWL research for nearly 20 years. Through simulations and experiments, our research has led us to understand more precisely the physical principles for how shock waves fracture kidney stones. Based on this work, we are now investigating an alternative noninvasive method to fragment stones by using ultrasound pulses rather than shock waves to fragment stones, called burst wave lithotripsy or BWL. Ultrasound bursts consist of consecutive acoustic cycles that can accumulate to concentrate energy within the stone, enabling comminution at relatively low peak pressures of the incident sound field. In this way, BWL can cause stresses and fractures in the stone through resonances, much in the way an opera singer can shatter a wine glass with their voice. A key characteristic of this method is that the size fragments generated when the stone disintegrates is controlled by the ultrasound frequency. In this way, the technique can be 'tuned' to create small fragments that the patients will pass naturally, and potentially improve the success rate of lithotripsy procedures.

Presentation from the 71st Annual Meeting of the American Physical Society's Division of Fluid Dynamics, 19–20 November 2018.

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