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Published March 4, 2013 | Published
Book Section - Chapter Open

Exploring ultrasound-modulated optical tomography at clinically useful depths using the photorefractive effect


For years, ultrasound-modulated optical tomography (UOT) has been proposed to image optical contrasts deep inside turbid media (such as biological tissue) at an ultrasonic spatial resolution. The reported imaging depth so far, however, has been limited, preventing this technique from finding broader applications. In this work, we present our latest experimental explorations that push UOT to clinically useful imaging depths, achieved through optimizing from different aspects. One improvement is the use of a large aperture fiber bundle, which more effectively collects the diffused light, including both ultrasound-modulated and unmodulated portions, from the turbid sample and then sends it to the photorefractive material. Another endeavor is employment of a large aperture photorefractive polymer film for demodulating the ultrasound-induced phase modulation. Compared with most UOT detection schemes, the polymer film based setup provides a much higher etendue as well as photorefractive two-beam-coupling gain. Experimentally, we have demonstrated enhanced sensitivity and have imaged through tissue-mimicking samples up to 9.4 cm thick at the ultrasonically-determined spatial resolutions.

Additional Information

© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE). The authors thank Sandra Matteucci for editing the manuscript, and Nitto Denko Technical at Oceanside, CA for providing the photorefractive polymer film used in the current study. This research is sponsored in part by the National Academies Keck Futures Initiative grant IS 13, National Institute of Health grants DP1 EB016986 (NIH Director's Pioneer Award), R01 EB000712 and U54 CA136398. L.W. has a financial interest in Microphotoacoustics, Inc. and Endra, Inc., which, however, did not support this work.

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