Bubble proliferation in shock wave lithotripsy occurs during inertial collapse

Yuri A. Pishchalnikov, James A. McAteer, Irina V. Pishchalnikova, James C. Williams, Michael R. Bailey, Oleg A. Sapozhnikov

Research output: Chapter in Book/Report/Conference proceedingConference contribution

12 Scopus citations

Abstract

In shock wave lithotripsy (SWL), firing shock pulses at slow pulse repetition frequency (0.5 Hz) is more effective at breaking kidney stones than firing shock waves (SWs) at fast rate (2 Hz). Since at fast rate the number of cavitation bubbles increases, it appears that bubble proliferation reduces the efficiency of SWL. The goal of this work was to determine the basis for bubble proliferation when SWs are delivered at fast rate. Bubbles were studied using a high-speed camera (Imacon 200). Experiments were conducted in a test tank filled with nondegassed tap water at room temperature. Acoustic pulses were generated with an electromagnetic lithotripter (DoLi-50). In the focus of the lithotripter the pulses consisted of a ∼60MPa positive-pressure spike followed by up to -8MPa negative-pressure tail, all with a total duration of about 7 μs. Nonlinear propagation steepened the shock front of the pulses to become sufficiently thin (∼0.03 μm) to impose differential pressure across even microscopic bubbles. High-speed camera movies showed that the SWs forced preexisting microbubbles to collapse, jet, and break up into daughter bubbles, which then grew rapidly under the negative-pressure phase of the pulse, but later coalesced to re-form a single bubble. Subsequent bubble growth was followed by inertial collapse and, usually, rebound. Most, if not all, cavitation bubbles emitted micro-jets during their first inertial collapse and re-growth. After jetting, these rebounding bubbles could regain a spherical shape before undergoing a second inertial collapse. However, either upon this second inertial collapse, or sometimes upon the first inertial collapse, the rebounding bubble emerged from the collapse as a cloud of smaller bubbles rather than a single bubble. These daughter bubbles could continue to rebound and collapse for a few cycles, but did not coalesce. These observations show that the positive-pressure phase of SWs fragments preexisting bubbles but this initial fragmentation does not yield bubble proliferation, as the daughter bubbles coalesce to reform a single bubble. Instead, bubble proliferation is the product of the subsequent inertial collapses.

Original languageEnglish (US)
Title of host publicationNonlinear Acoustics - Fundamentals and Applications - ISNA18 - 18th International Symposium on Nonlinear Acoustics
Pages460-463
Number of pages4
DOIs
StatePublished - Aug 15 2008
Event18th International Symposium on Nonlinear Acoustics, ISNA18 - Stockholm, Sweden
Duration: Jul 7 2008Jul 10 2008

Publication series

NameAIP Conference Proceedings
Volume1022
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other18th International Symposium on Nonlinear Acoustics, ISNA18
CountrySweden
CityStockholm
Period7/7/087/10/08

Keywords

  • Cavitation
  • Cavitation nuclei
  • High-speed photography
  • Microbubbles
  • Shock waves

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Pishchalnikov, Y. A., McAteer, J. A., Pishchalnikova, I. V., Williams, J. C., Bailey, M. R., & Sapozhnikov, O. A. (2008). Bubble proliferation in shock wave lithotripsy occurs during inertial collapse. In Nonlinear Acoustics - Fundamentals and Applications - ISNA18 - 18th International Symposium on Nonlinear Acoustics (pp. 460-463). (AIP Conference Proceedings; Vol. 1022). https://doi.org/10.1063/1.2956259