Steady-state reflectance spectroscopy in the P_3 approximation

Hull, Edward L.; Foster, Thomas H.

doi:10.1364/josaa.18.000584

Cited by 146 publications

(136 citation statements)

References 20 publications

Supporting

Mentioning

133

Contrasting

Order By: Relevance

“…(dotted curves) as adopted elsewhere 45 . We note that within the diffusion range (roughly up to μ a = 0.1 mm ) the two ways to account the source position are practically equivalent.…”

Section: Comparisons Mc/de For F(z|t) and F(z|ρ)mentioning

confidence: 99%

Structural white-matter connections mediating distinct behavioral components of spatial neglect in right brain-damaged patients

Vaessen

Saj̈

Lövblad

et al. 2016

Cortex

View full text Add to dashboard Cite

We propose a comprehensive statistical approach describing the penetration depth of light in random media. The presented theory exploits the concept of probability density function f(z|ρ, t) for the maximum depth reached by the photons that are eventually re-emitted from the surface of the medium at distance ρ and time t. Analytical formulas for f, for the mean maximum depth 〈z max 〉 and for the mean average depth z reached by the detected photons at the surface of a diffusive slab are derived within the framework of the diffusion approximation to the radiative transfer equation, both in the time domain and the continuous wave domain. Validation of the theory by means of comparisons with Monte Carlo simulations is also presented. The results are of interest for many research fields such as biomedical optics, advanced microscopy and disordered photonics.

show abstract

“…(dotted curves) as adopted elsewhere 45 . We note that within the diffusion range (roughly up to μ a = 0.1 mm ) the two ways to account the source position are practically equivalent.…”

Section: Comparisons Mc/de For F(z|t) and F(z|ρ)mentioning

confidence: 99%

Structural white-matter connections mediating distinct behavioral components of spatial neglect in right brain-damaged patients

Vaessen

Saj̈

Lövblad

et al. 2016

Cortex

View full text Add to dashboard Cite

show abstract

“…To model the propagation of light in tissue, we have adopted the diffusion-P 3 hybrid model with extrapolated boundary conditions for semi-infinite media proposed by Hull and Foster 4 . Briefly, this model replaces in incident pencil beam with two equally weighted isotropic point sources, one located on the surface and one at a depth equal to twice the medium's transport mean free path.…”

Section: Discussionmentioning

confidence: 99%

“…To make the fitting algorithm easy to use and interactive, we implemented a graphical user interface (GUI), as shown in figure 2. The fitting of normalized data can be performed a number of ways, including: on a wavelength-by wavelength basis; 4,5 by normalizing the data to that acquired at the smallest source-detector separation across all wavelengths; 6 or by normalizing to the reflectance at 650 nm at a single source-detector separation. 7 In this work, we have adopted the latter method.…”

Section: Discussionmentioning

confidence: 99%

Diffuse reflectance spectra measured in vivo in human tissues during Photofrin-mediated pleural photodynamic therapy

Finlay

Zhu

Dimofte

et al. 2006

Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XV

View full text Add to dashboard Cite

Optimal delivery of light in photodynamic therapy (PDT) requires not only optimal placement and power of light sources, but knowledge of the dynamics of light propagation in the tissue being treated and in the surrounding normal tissue, and of their respective accumulations of sensitizer. In an effort to quantify both tissue optical properties and sensitizer distribution, we have measured fluorescence emission and diffuse reflectance spectra at the surface of a variety of tissue types in the thoracic cavities of human patients. The patients studied here were enrolled in Phase II clinical trials of Photofrin-mediated PDT for the treatment of non-small cell lung cancer and cancers with pleural effusion. Patients were given Photofrin at dose of 2 mg per kg body weight 24 hours prior to treatment. Each patient received surgical resection of the affected lung and pleura. Patients received intracavity PDT at 630nm to a dose of 30 J/cm 2 , as determined by isotropic detectors sutured to the cavity walls. We measured the diffuse reflectance spectra before and after PDT in various positions within the cavity, including tumor, diaphragm, pericardium, skin, and chest wall muscle in 5 patients. The measurements we acquired using a specially designed fiber optic-based probe consisting of one fluorescence excitation fiber, one white light delivery fiber, and 9 detection fibers spaced at distances from 0.36 to 7.8 mm from the source, all of which are imaged via a spectrograph onto a CCD, allowing measurement of radially-resolved diffuse reflectance and fluorescence spectra. The light sources for these two measurements (a 403-nm diode laser and a halogen lamp, respectively) were blocked by computer-controlled shutters, allowing sequential fluorescence, reflectance, and background acquisition. The diffuse reflectance was analyzed to determine the absorption and scattering spectra of the tissue and from these, the concentration and oxygenation of hemoglobin and the local drug uptake. The total hemoglobin concentration in normal tissues varied from 50 to 300 μM, and the oxygen saturation was generally above 60%. One tumor measured exhibited higher hemoglobin concentration and lower saturation.

show abstract

“…Several researchers have proposed diffusion models with increased orders of approximation to the RTE for the purpose of studying superficial tissues. For example, Hull and Foster employed the P 3 approximation to derive the Green's function of RTE and demonstrated successful reconstruction of sample optical properties at 0.43 mm source-detector separation [15]. By introducing the δ-Eddington approximation to the source function, Star et al and Prahl demonstrated that this approach could improve the depiction of the photon energy transport near boundaries or sources more precisely than did a typical diffusion equation [16,17].…”

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

View full text Add to dashboard Cite

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.

show abstract

Steady-state reflectance spectroscopy in the P_3 approximation

Cited by 146 publications

References 20 publications

Structural white-matter connections mediating distinct behavioral components of spatial neglect in right brain-damaged patients

Structural white-matter connections mediating distinct behavioral components of spatial neglect in right brain-damaged patients

Diffuse reflectance spectra measured in vivo in human tissues during Photofrin-mediated pleural photodynamic therapy

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

Contact Info

Product

Resources

About