Spatial control of cavitation in therapeutic ultrasound
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2006
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| Online Access: | http://hdl.handle.net/1721.1/30171 |
| _version_ | 1826198555173322752 |
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| author | Gauthier, Thomas P., 1980- |
| author2 | Kullervo Hynynen. |
| author_facet | Kullervo Hynynen. Gauthier, Thomas P., 1980- |
| author_sort | Gauthier, Thomas P., 1980- |
| collection | MIT |
| description | Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005. |
| first_indexed | 2024-09-23T11:06:21Z |
| format | Thesis |
| id | mit-1721.1/30171 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T11:06:21Z |
| publishDate | 2006 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/301712019-04-11T03:32:41Z Spatial control of cavitation in therapeutic ultrasound Gauthier, Thomas P., 1980- Kullervo Hynynen. Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. Electrical Engineering and Computer Science. Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005. Includes bibliographical references (p. 60-65). Inertial cavitation has been implicated as the primary mechanism for a host of emerging applications. In all these applications, the main concern is to induce cavitation in perfectly controlled locations in the field; this means specifically to be able to achieve cavitation threshold at the geometrical focus of the transducer without stimulating its near field. In this study, we make use of dual-frequency methods to preferentially lower the cavitation threshold at the focus relative to the rest of the field. One family of dual-frequency driving waveforms is evaluated in a bubble model incorporating rectified diffusion. Theoretical predictions based on Sokka's work (Sokka 2003a) are confirmed in vitro using Optison[TM], a commercially available contrast agent. The performance of the rest of acoustic field in suppressing cavitation when cavitation is induced at the focus is investigated theoretically and checked experimentally. This first part shows that dual-frequency phased arrays could be used to precisely control cavitation. Cavitation threshold is proved to be 1.2 times higher in the near field than at the focus. One of the main limitations of the aforementioned protocol is that it is tightly controlled. As an example, Optison[TM] has a mean bubble size of 2 - 4.5 [micro]m, which means that the initial bubble radii will fall in this range. Since cavitation threshold has been proved to depend on this parameter, using ultrasound contrast agents allows for more predictable results. Therefore, in the second half of this study, we propose a focused ultrasound protocol that induces and monitors gas bubbles at the focus and allows for ex vivo validation of the aforementioned theoretical results. The experiments involve fresh rabbit tissue and a statistical analysis is performed over data collected from back muscle. (cont.) Moreover, the experimental apparatus is designed to be MRI-compatible to make future in vivo assessments feasible. This second half of the study demonstrates that the theoretical predictions made earlier can reliably be used to predict dual-frequency cavitation thresholds. It also suggests that clinical use of dual-frequency excitations might be a solution to the problem of spatial control of cavitation. by Thomas P. Gauthier. S.M. 2006-03-24T18:26:14Z 2006-03-24T18:26:14Z 2005 2005 Thesis http://hdl.handle.net/1721.1/30171 60678405 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 65 p. 3401422 bytes 3407590 bytes application/pdf application/pdf application/pdf Massachusetts Institute of Technology |
| spellingShingle | Electrical Engineering and Computer Science. Gauthier, Thomas P., 1980- Spatial control of cavitation in therapeutic ultrasound |
| title | Spatial control of cavitation in therapeutic ultrasound |
| title_full | Spatial control of cavitation in therapeutic ultrasound |
| title_fullStr | Spatial control of cavitation in therapeutic ultrasound |
| title_full_unstemmed | Spatial control of cavitation in therapeutic ultrasound |
| title_short | Spatial control of cavitation in therapeutic ultrasound |
| title_sort | spatial control of cavitation in therapeutic ultrasound |
| topic | Electrical Engineering and Computer Science. |
| url | http://hdl.handle.net/1721.1/30171 |
| work_keys_str_mv | AT gauthierthomasp1980 spatialcontrolofcavitationintherapeuticultrasound |