Quantitative spectroscopy of superficial turbid media

Tseng, Sheng Hao; Hayakawa, Carole K.; Tromberg, Bruce J.; Spanier, Jerome; Durkin, Anthony J.

doi:10.1364/ol.30.003165

Cited by 24 publications

(23 citation statements)

References 6 publications

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“…A modified two-layer standard diffusion model is then able to describe photon transport in this geometry at source-detector separations shorter than 3 mm. Monte Carlo simulations and homogeneous phantom studies demonstrated that the optical properties of samples can be recovered to within 5% of true values using this new diffusing probe with 2.5-mm source-detector separation [1].…”

Section: Introductionmentioning

confidence: 89%

“…1, is comprised of two optical fibers (3M, core diameter = 600 μm, NA = 0.37) for delivering and collecting photons, and a highly scattering layer (Spectralon Slab, Labsphere) to diffuse photons from the source fiber. A modified two-layer, diffusion-based model is employed to deduce the sample optical properties from measured phase delay and amplitude demodulation [1].…”

Section: Methodsmentioning

confidence: 99%

“…Time-domain and frequencydomain DOS usually employ source-detector separations larger than 5 mm, thus enabling the use of a standard diffusion model to accurately recover tissue optical properties [1], [3]. Since the source-detector separation is roughly proportional to the interrogation depth [4] in DOS, determination of the optical properties of superficial volumes of tissues requires a sourcedetector separation shorter than 3 mm in addition to improved theoretical models, such as or Monte Carlo methods [5], [6].…”

Section: Introductionmentioning

confidence: 99%

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Determination of Optical Properties of Superficial Volumes of Layered Tissue Phantoms

Tseng

Hayakawa

Spanier

et al. 2008

IEEE Trans. Biomed. Eng.

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Previously, we reported the design of a new diffusing probe that employs a standard two-layer diffusion model to recover the optical properties of turbid samples. This particular probe had a sourcedetector separation of 2.5 mm and performance was validated with Monte Carlo simulations and homogeneous phantom experiments. The goal of the current study is to characterize the performance of this new method in the context of two-layer phantoms that mimic the optical properties of human skin. We analyze the accuracy of the recovered top layer optical properties and their dependences on the thickness of the top layer of two-layer phantoms. Our results demonstrate that the optical properties of the top layer can be accurately determined with a 1.6 mm source-detector separation diffusing probe when this layer thickness is as thin as 1 mm. Monte Carlo simulations illustrate that the interrogation depth can be further decreased by shortening the source-detector separation.

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Section: Introductionmentioning

confidence: 89%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Determination of Optical Properties of Superficial Volumes of Layered Tissue Phantoms

Tseng

Hayakawa

Spanier

et al. 2008

IEEE Trans. Biomed. Eng.

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“…In general, the standard diffusion equation (SDE) derived from the radiative transport equation (RTE) is used to describe photon transport for its simplicity and computational efficiency [8,9]. However, the validity of SDE is held only when the scattering is much larger than the absorption and the photon travel length surpasses five to ten transport mean free paths [l t = 1/(μ a + μ s ')] [10][11][12]. Therefore, DRS techniques that work with the SDE are usually applied to study highly scattering thick tissue, such as breast or brain, in the 600 to 1000 nm wavelength region and at large source-detector separations [4,13,14].…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, to investigate superficial volumes of tissues with DRS, it is essential to limit the source-detector separation to be less than 5 mm, but SDE has been proven ineffective in this regime [10][11][12]. Several researchers have proposed diffusion models with increased orders of approximation to the RTE for the purpose of studying superficial tissues.…”

Section: Introductionmentioning

confidence: 99%

A linear gradient line source facilitates the use of diffusion models with high order approximation for efficient, accurate turbid sample optical properties recovery

Lee¹,

Hung²,

Liao³

et al. 2014

Biomed. Opt. Express

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Abstract:In this paper, we demonstrate that a scanning MEMS mirror can be employed to create a linear gradient line source that is equivalent to a planar source. This light source setup facilitates the use of diffusion models of increased orders of approximation having closed form solution, and thus enhance the efficiency and accuracy in sample optical properties recovery. In addition, compared with a regular planar light source, the linear gradient line source occupies much less source area and has an elevated measurement efficiency. We employed a δ-P 1 diffusion equation with a closed form solution and carried out a phantom study to understand the performance of this new method in determining the absorption and scattering properties of turbid samples. Moreover, our Monte Carlo simulation results indicated that this geometry had probing depths comparable to those of the conventional diffuse reflectance measurement geometry with a source-detector separation of 3 mm. We expect that this new source setup would facilitate the investigating of superficial volumes of turbid samples in the wavelength regions where tissue absorption coefficients are comparable to scattering coefficients.

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Quantitative near infrared spectroscopic analysis of Q‐Switched Nd:YAG treatment of generalized argyria

et al. 2013

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Background and Objective Generalized argyria is a blue-gray hyperpigmentation of the skin resulting from ingestion or application of silver compounds, such as silver colloid. Case reports have noted improvement after Q-Switched Neodymium--Yttrium Aluminum Garnet laser (1064nm QS Nd:YAG) laser treatment to small surface areas. No reports have objectively monitored laser treatment of generalized argyria over large areas of skin, nor have long-term outcomes been evaluated. Study Design/Materials and Methods An incremental treatment plan was developed for a subject suffering from argyria. A quantitative near infrared spectroscopic measurement technique was employed to non-invasively analyze tissue-pigment characteristics pre- and post-laser treatment. Post-treatment measurements were collected at weeks 1, 2, 3, and 4, and again at 1 year. Results Immediate apparent removal of pigment was observed with 1 Q-switched 1064 nm Nd:YAG laser treatment (3-6 mm spot; 0.8-2 J/cm2) per area. Entire face, neck, upper chest and arms were treated over multiple sessions. Treatments were very painful and general anesthesia was utilized in order to treat large areas. Near-infrared spectroscopy was used to characterize and quantify the concentration of silver particles in the dermis based on the absorption features of the silver particles as well as the optical scattering effects they impart. We were able to estimate that there was, on average, 0.042 mg/mL concentration of silver prior to treatment and that these levels went below the minimum detectable limit of the instrument post-treatment. There was no recurrence of discoloration over the 1-year study period. Conclusion QS 1064 nm laser treatment of argyria is a viable method to restore normal skin pigmentation with no evidence of recurrence over study period. Quantitative spectroscopic measurements, 1) confirmed dyspigmentation was due to silver, 2) validated our clinical assessment of no recurrence up to one year post-treatment and 3) indicated no collateral tissue damage with treatments.

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Quantitative spectroscopy of superficial turbid media

Cited by 24 publications

References 6 publications

Determination of Optical Properties of Superficial Volumes of Layered Tissue Phantoms

Determination of Optical Properties of Superficial Volumes of Layered Tissue Phantoms

A linear gradient line source facilitates the use of diffusion models with high order approximation for efficient, accurate turbid sample optical properties recovery

Quantitative near infrared spectroscopic analysis of Q‐Switched Nd:YAG treatment of generalized argyria

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