Focused ultrasound therapy can be enhanced with microbubbles by thermal and cavitation effects. However, localization of treatment becomes difficult as bioeffects can occur outside of the target region. Spatial control of gas bubbles can be achieved with
acoustic vaporization of perfluorocarbon droplets. This study was undertaken to determine the acoustic parameters for bubble production by droplet vaporization and how it
depends on the acoustic conditions and droplet physical parameters. Droplets of varying sizes were sonicated in vitro with a focused ultrasound transducer and varying frequency and exposure. Simultaneous measurements of the vaporization and inertial cavitation thresholds were performed. The results show that droplets cannot be vaporized at low frequency without inertial cavitation occurring. However, the vaporization threshold decreased with increasing frequency, exposure and droplet size. In summary, we have demonstrated that droplet vaporization is feasible for clinically-relevant sized droplets and acoustic exposures.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/18874 |
| Date | 15 February 2010 |
| Creators | Schad, Kelly C. |
| Contributors | Hynynen, Kullervo |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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