A novel method for estimating the focal size of two confocal high-intensity focused ultrasound transducers

Wen Shiang Chen, Ping Mo Ma, Hao Li Liu, Chih Kuang Yeh*, Min Shin Chen, Chein Wei Chang

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

2 Scopus citations


Estimating the focal size and position of a high-intensity focused ultrasound (HIFU) transducer remains a challenge since traditional methods, such as hydrophone scanning or schlieren imaging, cannot tolerate high pressures, are directional, or provide low resolution. The difficulties increase when dealing with the complex beam pattern of a multielement HIFU transducer array, e.g., two transducers facing each other. In the present study we show a novel approach to the visualization of the HIFU focus by using shockwave-generated bubbles and a diagnostic B-mode scanner. Bubbles were generated and pushed by shock waves toward the HIFU beam, and were trapped in its pressure valleys. These trapped bubbles moved along the pressure valleys and thereby delineated the shape and size of the HIFU beam. The main and sidelobes of 1.1- and 3.5 MHz HIFU beams were clearly visible, and could be measured with a millimeter resolution. The combined foci could also be visualized by observing the generation of sustained inertial cavitation and enhanced scattering. The results of this study further demonstrate the possibility of reducing the inertial cavitation threshold by the local introduction of shock wave-generated bubbles, which might be useful when bubble generation and cavitation-related bioeffects are intended within a small region in vivo.

Original languageEnglish
Pages (from-to)3740-3749
Number of pages10
JournalJournal of the Acoustical Society of America
Issue number6
StatePublished - 06 2005
Externally publishedYes


Dive into the research topics of 'A novel method for estimating the focal size of two confocal high-intensity focused ultrasound transducers'. Together they form a unique fingerprint.

Cite this