Computation Of Acoustic Ressure Fields Produced In Feline Brain By High-Intensity Focused Ultrasound

In 1975, Dunn et al. (Jasa 58:512-514) shothat 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 those experimental exposures by estimating them using nonlinear rather than 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, with the compressional amplitude of the wave becoming greater, and the rarefactional amplitude becoming lower than the values calculated using linear theory. The implications of these results for clinical exposures are discussed.

Name thesis:degree_name

M.S. in Physics

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Physics and Astronomy

Year dc:date.available

2016

Author dc:creator

• Omidi, Nazanin

Contributors dc:contributor

• Cecille Labuda
• Joel Mobley
• Charles C. Church

• Biomedical Acoustics
• Biomedical Ultrasound
• Physics

Repository record dc:identifier

https://egrove.olemiss.edu/etd/1115

OAI identifier oai:identifier

oai:egrove.olemiss.edu:etd-2114