Advantage of annular focus generation by sector-vortex array in cavitation-enhanced high-intensity focused ultrasound treatment

Hayato Jimbo, Ryo Takagi, Kei Taguchi, Shin Yoshizawa, Shin Ichiro Umemura

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

High-intensity focused ultrasound (HIFU) is a noninvasive method for cancer treatment. One of the disadvantages of this method is that it has a long total treatment time because of the smallness of the treatment volume by a single exposure. To solve this problem, we have proposed a method of cavitation-enhanced heating, which utilized the heat generated by oscillating the cavitation bubbles, in combination with the method of lateral enlargement of a HIFU focal zone to minimize the surface volume ratio. In a previous study, focal spot scanning at multiple points was employed for the enlargement. This method involves nonlinear propagation and absorption due to the high spatial-peak temporal-peak (SPTP) intensity in addition to the cavitation-enhanced heating. However, it is difficult to predict the size and position of the coagulation volume because they are significantly affected by the nonlinear parameters of the tissue. In this study, a sector vortex method was employed to directly synthesize an annular focal pattern. Since this method can keep the SPTP intensity at a manageably low level, nonlinear propagation and absorption can be minimized. Experimental results demonstrate that the coagulation was generated only in the region where both the cavitation cloud and the heating ultrasound were matched. The proposed method will make the cavitation-enhanced HIFU treatment more accurate and predictable.

Original languageEnglish
Article number07KF19
JournalJapanese journal of applied physics
Volume55
Issue number7
DOIs
Publication statusPublished - 2016 Jul

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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