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Investigating ultrasound–light interaction in scattering media

Huang, Yujia and Cua, Michelle and Brake, Joshua and Liu, Yan and Yang, Changhuei (2020) Investigating ultrasound–light interaction in scattering media. Journal of Biomedical Optics, 25 (2). Art. No. 025002. ISSN 1083-3668. PMCID PMC7043283.

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Significance: Ultrasound-assisted optical imaging techniques, such as ultrasound-modulated optical tomography, allow for imaging deep inside scattering media. In these modalities, a fraction of the photons passing through the ultrasound beam is modulated. The efficiency by which the photons are converted is typically referred to as the ultrasound modulation’s “tagging efficiency.” Interestingly, this efficiency has been defined in varied and discrepant fashion throughout the scientific literature. Aim: The aim of this study is the ultrasound tagging efficiency in a manner consistent with its definition and experimentally verify the contributive (or noncontributive) relationship between the mechanisms involved in the ultrasound optical modulation process. Approach: We adopt a general description of the tagging efficiency as the fraction of photons traversing an ultrasound beam that is frequency shifted (inclusion of all frequency-shifted components). We then systematically studied the impact of ultrasound pressure and frequency on the tagging efficiency through a balanced detection measurement system that measured the power of each order of the ultrasound tagged light, as well as the power of the unmodulated light component. Results: Through our experiments, we showed that the tagging efficiency can reach 70% in a scattering phantom with a scattering anisotropy of 0.9 and a scattering coefficient of 4  mm⁻¹ for a 1-MHz ultrasound with a relatively low (and biomedically acceptable) peak pressure of 0.47 MPa. Furthermore, we experimentally confirmed that the two ultrasound-induced light modulation mechanisms, particle displacement and refractive index change, act in opposition to each other. Conclusion: Tagging efficiency was quantified via simulation and experiments. These findings reveal avenues of investigation that may help improve ultrasound-assisted optical imaging techniques.

Item Type:Article
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URLURL TypeDescription CentralArticle
Huang, Yujia0000-0001-7667-8342
Brake, Joshua0000-0002-5113-6886
Liu, Yan0000-0002-5837-4908
Yang, Changhuei0000-0001-8791-0354
Additional Information:© 2020 The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. Paper 190411R received Nov. 27, 2019; accepted for publication Feb. 6, 2020; published online Feb. 26, 2020. We thank Jian Xu for helpful discussions and help in experiment setup. We thank Dr. Antony C.S. Chan for constructive discussions. We acknowledge gift contributions from Kernel LLC that supported this work. Michelle Cua was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC PGSD3). Authors have no conflicts of interest.
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)PGSD3
Subject Keywords:acousto-optics; scattering; tomography
Issue or Number:2
PubMed Central ID:PMC7043283
Record Number:CaltechAUTHORS:20200228-130201996
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Official Citation:Yujia Huang, Michelle Cua, Joshua Brake, Yan Liu, and Changhuei Yang "Investigating ultrasound–light interaction in scattering media," Journal of Biomedical Optics 25(2), 025002 (26 February 2020).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101641
Deposited By: Tony Diaz
Deposited On:28 Feb 2020 22:27
Last Modified:11 Nov 2020 00:36

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