We propose to design, develop and experimentally verify the performance of a highly innovative, acoustooptic measurement system with sub-millimeter resolution, appropriate for characterization of ultrasound fields encountered in clinical applications. Such a system with spatial and temporal resolutions proposed here is not currently available. The innovative elements of the proposed research include the development of a tapered fiber optic (FO) sensor with an active diameter on the order of 5-7 mu m (microns) that operates in the frequency range from 0.1 - 100 MHz and is sufficiently robust to measure fields generated by High Frequency Focused Ultrasound (HIFU) transducers used for treatment of malignant tissues. The small physical dimensions of the sensor will obviate the need for spatial averaging corrections so that true pressure-time (p-t) waveforms can be faithfully recorded. The recording of these waveforms is essential in order to determine all clinically relevant safety indicators, such as Mechanical and Thermal Indices. The sensitivity of the FO sensor will be comparable with that typical of currently used hydrophone probes. As optical fibers are inherently immune to non-optical electromagnetic fields stimuli, this proposed system has a potential of being nearly immune to Electromagnetic Field Interference (EMI). In addition, the intrinsically rugged characteristics of the fiber constitute an attractive feature as the existing ultrasound hydrophone probes are fragile and, in practice, cannot be used in therapeutic HIFU fields. Also, the miniature physical dimensions of the fiber optic sensor make it potentially well suited for in vivo measurements, virtually impossible with the currently available ultrasound hydrophone probes. Preliminary data indicate that once fully developed and calibrated, the acousto-optic system will form an important breakthrough in acoustic measurements of both diagnostic and therapeutic fields. Such outcome will also accelerate further advances of ultrasound applications in medicine. These advances are important because ultrasound offers nonionizing interaction with tissue and is economically favorable in comparison with other imaging and interventional modalities. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Type
Research Project (R01)
Project #
5R01EB007117-02
Application #
7281167
Study Section
Biomedical Imaging Technology Study Section (BMIT)
Program Officer
Lopez, Hector
Project Start
2006-09-01
Project End
2009-08-31
Budget Start
2007-09-01
Budget End
2008-08-31
Support Year
2
Fiscal Year
2007
Total Cost
$319,848
Indirect Cost
Name
Drexel University
Department
Type
Schools of Engineering
DUNS #
002604817
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
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Lewin, Peter A (2010) Nonlinear Acoustics in Ultrasound Metrology and other Selected Applications. Phys Procedia 3:17-23
Umchid, S; Gopinath, R; Srinivasan, K et al. (2009) Development of calibration techniques for ultrasonic hydrophone probes in the frequency range from 1 to 100 MHz. Ultrasonics 49:306-11
Gopinath Minasamudram, Rupa; Arora, Piyush; Gandhi, Gaurav et al. (2009) Thin film metal coated fiber optic hydrophone probe. Appl Opt 48:G77-82
Wojcik, J; Kujawska, T; Nowicki, A et al. (2008) Fast prediction of pulsed nonlinear acoustic fields from clinically relevant sources using time-averaged wave envelope approach: comparison of numerical simulations and experimental results. Ultrasonics 48:707-15