Mr. Binh C. Le Profile

Binh C. Le

at Beckman Laser Institute and Medical Clinic

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Author

Publications (4)

SPIE Journal Paper | 23 March 2022 Open Access

Quantifying the confounding effect of pigmentation on measured skin tissue optical properties: a comparison of colorimetry with spatial frequency domain imaging

Thinh Phan, Rebecca Rowland, Adrien Ponticorvo, Binh Le, Seyed Sharif, Gordon Kennedy, Robert Wilson, Anthony Durkin

JBO, Vol. 27, Issue 03, 036002, (March 2022) https://doi.org/10.1117/12.10.1117/1.JBO.27.3.036002

KEYWORDS: Skin, Tissue optics, Optical properties, Scattering, Absorption, Optical testing, Colorimetry, Tissues, Data modeling, Monte Carlo methods

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Significance: Spatial frequency domain imaging (SFDI) is a wide-field diffuse optical imaging technique for separately quantifying tissue reduced scattering (μs ′ ) and absorption (μa) coefficients at multiple wavelengths, providing wide potential utility for clinical applications such as burn wound characterization and cancer detection. However, measured μs ′ and μa can be confounded by absorption from melanin in patients with highly pigmented skin. This issue arises because epidermal melanin is highly absorbing for visible wavelengths and standard homogeneous light–tissue interaction models do not properly account for this complexity. Tristimulus colorimetry (which quantifies pigmentation using the L * “lightness” parameter) can provide a point of comparison between μa, μs ′ , and skin pigmentation. Aim: We systematically compare SFDI and colorimetry parameters to quantify confounding effects of pigmentation on measured skin μs ′ and μa. We assess the correlation between SFDI and colorimetry parameters as a function of wavelength. Approach: μs ′ and μa from the palm and ventral forearm were measured for 15 healthy subjects with a wide range of skin pigmentation levels (Fitzpatrick types I to VI) using a Reflect RS® (Modulim, Inc., Irvine, California) SFDI instrument (eight wavelengths, 471 to 851 nm). L * was measured using a Chroma Meter CR-400 (Konica Minolta Sensing, Inc., Tokyo). Linear correlation coefficients were calculated between L * and μs ′ and between L * and μa at all wavelengths. Results: For the ventral forearm, strong linear correlations between measured L * and μs ′ values were observed at shorter wavelengths (R > 0.92 at ≤659 nm), where absorption from melanin confounded the measured μs ′ . These correlations were weaker for the palm (R < 0.59 at ≤659 nm), which has less melanin than the forearm. Similar relationships were observed between L * and μa. Conclusions: We quantified the effects of epidermal melanin on skin μs ′ and μa measured with SFDI. This information may help characterize and correct pigmentation-related inaccuracies in SFDI skin measurements.

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Proceedings Article | 5 March 2021 Presentation

Quantifying the confounding effect of pigmentation on measured skin tissue optical properties: A comparison of colorimetry with Spatial Frequency Domain Imaging

Thinh Phan, Rebecca Rowland, Adrien Ponticorvo, Binh Le, Robert Wilson, Seyed Sharif, Gordon Kennedy, Anthony Durkin

Proceedings Volume 11618, 1161810 (2021) https://doi.org/10.1117/12.2576800

KEYWORDS: Skin, Optical properties, In vivo imaging, Tissue optics, Scattering, Remote sensing, Range imaging, Monte Carlo methods, Mie scattering, Light wave propagation

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SPIE Journal Paper | 10 February 2021 Open Access

Characterizing reduced scattering coefficient of normal human skin across different anatomic locations and Fitzpatrick skin types using spatial frequency domain imaging

Thinh Phan, Rebecca Rowland, Adrien Ponticorvo, Binh Le, Robert Wilson, Seyed Sharif, Gordon Kennedy, Nicole Bernal, Anthony Durkin

JBO, Vol. 26, Issue 02, 026001, (February 2021) https://doi.org/10.1117/12.10.1117/1.JBO.26.2.026001

KEYWORDS: Skin, Scattering, Optical properties, Absorption, In vivo imaging, Tissue optics, Wound healing, Tissues, Human subjects, Visible radiation

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Significance: Spatial frequency domain imaging (SFDI), a noncontact wide-field imaging technique using patterned illumination with multiple wavelengths, has been used to quantitatively measure structural and functional parameters of in vivo tissue. Using SFDI in a porcine model, we previously found that scattering changes in skin could potentially be used to noninvasively assess burn severity and monitor wound healing. Translating these findings to human subjects necessitates a better understanding of the variation in “baseline” human skin scattering properties across skin types and anatomical locations. Aim: Using SFDI, we aim to characterize the variation in the reduced scattering coefficient (μs′) for skin across a range of pigmentation and anatomic sites (including common burn locations) for normal human subjects. These measurements are expected to characterize baseline human skin properties to inform our use of SFDI for clinical burn severity and wound healing assessments. Approach: SFDI was used to measure μs′ in the visible- and near-infrared regime (471 to 851 nm) in 15 subjects at 10 anatomical locations. Subjects varied in age, gender, and Fitzpatrick skin type. Results: For all anatomical locations, the coefficient of variation in measured μs′ decreased with increasing wavelength. High intersubject variation in μs′ at visible wavelengths coincided with large values of the melanin extinction coefficient at those wavelengths. At 851 nm, where intersubject variation in μs′ was smallest for all anatomical locations and absorption from melanin is minimal, significant intrasubject differences in μs′ were observed at the different anatomical locations. Conclusions: Our study is the first report of wide-field mapping of human skin scattering properties across multiple skin types and anatomical locations using SFDI. Measured μs′ values varied notably between skin types at wavelengths where absorption from melanin was prominent. Additionally, μs′ varied considerably across different anatomical locations at 851 nm, where the confounding effects from melanin absorption are minimized.

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Proceedings Article | 6 March 2020 Paper

Comparing reduced scattering variation by skin type and tissue location using spatial frequency domain imaging for clinical burn wound imaging

Rebecca Rowland, Adrien Ponticorvo, Binh Cong Le, Thinh Phan, Nicole Bernal, Anthony Durkin

Proceedings Volume 11211, 1121102 (2020) https://doi.org/10.1117/12.2546391

KEYWORDS: Skin, Scattering, Optical properties, Tissues, Laser scattering, Wound healing, Tissue optics, Absorption, Animal model studies, Scatter measurement

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