ASA 126th Meeting Denver 1993 October 4-8

2pPA9. Detection and generation of transient acoustic microcavitation at 4.3-MHz center frequency.

Qihong Xu Xiaoyu Zheng Robert E. Apfel

Ctr. for Ultrasonics and Sonics, P.O. Box 2159, Yale Station, Yale Univ., New Haven, CT 06520

To study the potential bioeffects caused by applications of medical diagnostic ultrasound, a highly focused transducer with center frequency at 4.3 MHz was used to generate microcavitation in water seeded with polystyrene particles, and the cavitation was detected by a modified active detection system [R. A. Roy et al., J. Acoust. Soc. Am. 87, 2451--2458 (1990)]. The results show that the cavitation threshold is about 4.0 MPa in water seeded with polystyrene particles of 0.1 (mu)m diameter. The mechanical index corresponding to the cavitation threshold is 2.0, which is in the upper range of diagnostic ultrasound. The results also show that the cavitation depends strongly on the size of the polystyrene particles added in the water. [Work supported by NIH through Grant No. R01 CA39374.]