03/09/2016 Nazanin Omidi to give a talk at ASA 171 in Salt Lake City.

Nazanin Omidi will give a talk at the 171st Acoustical Society of America meeting in Salt Lake City Utah.  The meeting will be this upcoming May 2016. 

Nazanin Omidi, Cecille Labuda, Charles C. Church.  Computation of Ultrasonic Pressure Fields in Feline Brain​.

In 1975, Dunn et al. (JASA 58:512-514) showed that a simple relation describes the ultrasonic threshold for cavitation–induced changes in the mammalian brain. The thresholds for tissue damage were estimated for a variety of acoustic parameters in exposed feline brain. The goal of this study was to improve the estimates for acoustic pressures and intensities present in vivo during experimental exposures rather than estimating them using linear theory. In our current project, the acoustic pressure waveforms produced in the brains of anesthetized felines were numerically simulated for a spherically focused, nominally f1-transducer (focal length = 13 cm) at increasing values of the source pressure at frequencies of 1, 3, and 9 MHz. The corresponding focal intensities were correlated with the experimental data of Dunn et al. The focal pressure waveforms were also computed at the location of the true maximum. For low source pressures, the computed waveforms were the same as those determined using linear theory, and the focal intensities matched experimentally determined values. For higher source pressures, the focal pressure waveforms became increasingly distorted; similar results were obtained with increasing frequency.