Bubbles trapped at the coupling surface of the treatment head significantly reduce acoustic energy delivered in shock wave lithotripsy

Yuri A. Pishchalnikov, James A. McAteer, Irina V. Pishchalnikova, Spencer Beard, James C. Williams, Michael R. Bailey

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

2 Scopus citations

Abstract

The coupling efficiency of a "dry head" electromagnetic lithotripter (Dornier Compact Delta) was studied in vitro. A fiber-optic probe hydrophone (FOPH-500) was positioned in a test tank filled with degassed water. The tank was coupled through a semi-transparent latex membrane to the water-filled cushion of the lithotripter head, so that bubbles (air pockets) trapped between the two coupling surfaces could be easily observed and photographed. When gel was applied to both the latex membrane and the water cushion, numerous bubbles (some several millimeters in diameter) could be seen at the coupling interface. Hydrophone measurements in the geometric focus of the lithotripter showed that the acoustic pressure could be two times lower when bubbles were present than when they were manually removed. In our in vitro design, trapped bubbles could be easily observed and therefore removed from the acoustic path. However, during patient treatment with a dry-head lithotripter one cannot see whether bubbles are trapped against the skin. This study provides a demonstration of the dramatic effect that trapped bubbles can have on the amount of acoustic energy actually delivered for treatment.

Original languageEnglish (US)
Title of host publicationTHERAPEUTIC ULTRASOUND
Subtitle of host publication5th International Symposium on Therapeutic Ultrasound
Pages643-647
Number of pages5
DOIs
StatePublished - May 8 2006
EventTHERAPEUTIC ULTRASOUND: 5th International Symposium on Therapeutic Ultrasound - Boston, MA, United States
Duration: Oct 27 2005Oct 29 2005

Publication series

NameAIP Conference Proceedings
Volume829
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

OtherTHERAPEUTIC ULTRASOUND: 5th International Symposium on Therapeutic Ultrasound
CountryUnited States
CityBoston, MA
Period10/27/0510/29/05

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Keywords

  • Coupling gel
  • Shielding by trapped bubbles
  • Shock wave lithotripsy

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Pishchalnikov, Y. A., McAteer, J. A., Pishchalnikova, I. V., Beard, S., Williams, J. C., & Bailey, M. R. (2006). Bubbles trapped at the coupling surface of the treatment head significantly reduce acoustic energy delivered in shock wave lithotripsy. In THERAPEUTIC ULTRASOUND: 5th International Symposium on Therapeutic Ultrasound (pp. 643-647). (AIP Conference Proceedings; Vol. 829). https://doi.org/10.1063/1.2205553