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Published September 2009 | Published
Journal Article Open

On the speckle-free nature of photoacoustic tomography


Purpose: A long-standing conundrum is why photoacoustic tomography (PAT) possesses the unique ability to produce images devoid of speckle artifacts while all other coherent imaging technologies do not. Methods: In this paper, we explain the inherent mechanism that suppresses speckle in PAT, and the analysis was validated by simulations based on an experimental PAT system. Results: We found that the speckle-free feature of PAT results directly from the optical absorption contrast. Conclusions: All optical absorbers expand on laser excitation, and therefore all initial photoacoustic pressure rises are positive, which engenders strong correlations among the photoacoustic waves from the absorbers. As a result, prominent boundaries always build up in photoacousticimages and suppress the interior speckle.

Additional Information

© 2009 American Association of Physicists in Medicine. Received 29 April 2009; revised 30 June 2009; accepted for publication 5 July 2009; published 12 August 2009. The first two authors (Z.G. and L.L.) contributed equally to this paper. The authors would like to thank Meng-Lin Li, Minghua Xu, and Roger Zemp for useful discussions. This work was sponsored in part by National Institutes of Health Grant Nos. R01 NS46214 (BRP), R01 EB000712, R01 EB008085, and U54 CA136398 (NTR). L.V.W. has a financial interest in Endra, Inc., which, however, did not support this work.

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