The Experts below are selected from a list of 133869 Experts worldwide ranked by ideXlab platform
Steven L. Jacques - One of the best experts on this subject based on the ideXlab platform.
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Source of error in calculation of optical diffuse reflectance from turbid media using Diffusion Theory.
Computer methods and programs in biomedicine, 2000Co-Authors: Lihong V. Wang, Steven L. JacquesAbstract:Diffusion Theory and similarity relations were used to calculate the optical diffuse reflectance of an infinitely narrow laser beam incident upon a semi-infinite turbid medium. The results were analyzed by comparison with the accurate results from Monte Carlo simulations. Because a large number of photon packets were traced, the variance of the results from Monte Carlo simulations was small enough to reveal the detailed defects of the Diffusion Theory and the similarity relations, which are broadly used in photomedicine. We demonstrated that both Diffusion Theory and similarity relations provide very accurate results when the photon sources are isotropic and buried more deeply than one transport mean free path in turbid media. We found that the key factor affecting the accuracy of the Diffusion Theory application was the conversion from the infinitely narrow laser beam to an isotropic point source in turbid media.
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Analysis of Diffusion Theory and similarity relations for light reflectance by turbid media
Photon Migration and Imaging in Random Media and Tissues, 1993Co-Authors: Lihong V. Wang, Steven L. JacquesAbstract:ABSTRACT Both Diffusion Theory and similarity relations for light reflectance by semi-infinite turbid media have been analyzed by comparing their computational results with Monte Carlo simulation results. Since a large number of photon packets are traced, the variance of the MonteCarlo simulation results is small enough to reveal the detailed defects of Diffusion theories andsimilarity relations. We have demonstrated that both Diffusion Theory and similarity relationsprovide very accurate results when the photon sources are isotropic and one transport mean freepath below the turbid medium surface or deeper. This analysis has led to a hybrid model of Monte Carlo simulation and Diffusion Theory, which combines the accuracy advantage of Monte Carlo simulation and the speed advantage of Diffusion Theory. The similarity relations are used for the transition from the Monte Carlo simulation to the Diffusion Theory. 1. INTRODUCTION In laser-tissue interaction, there is a growing demand for accurate and fast models totheoretically predict the light distribution in turbid media, such as biological tissue, with givenoptical
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hybrid model of monte carlo simulation and Diffusion Theory for light reflectance by turbid media
Journal of The Optical Society of America A-optics Image Science and Vision, 1993Co-Authors: Lihong V. Wang, Steven L. JacquesAbstract:Light reflectance by semi-infinite turbid media is modeled by a hybrid of Monte Carlo simulation and Diffusion Theory, which combines the accuracy of Monte Carlo simulation near the source and the speed of Diffusion Theory distant from the source. For example, when the turbid medium has the following optical properties—absorption coefficient 1 cm^(-1), scattering coefficient 100 cm^(-1), anisotropy 0.9, and refractive-index-matched boundary—the hybrid simulation is 7 times faster than the pure Monte Carlo simulation (100,000 photon packets were traced), and the difference between the two simulations is within 2 standard deviations of the Monte Carlo simulation.
Lihong V. Wang - One of the best experts on this subject based on the ideXlab platform.
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Source of error in calculation of optical diffuse reflectance from turbid media using Diffusion Theory.
Computer methods and programs in biomedicine, 2000Co-Authors: Lihong V. Wang, Steven L. JacquesAbstract:Diffusion Theory and similarity relations were used to calculate the optical diffuse reflectance of an infinitely narrow laser beam incident upon a semi-infinite turbid medium. The results were analyzed by comparison with the accurate results from Monte Carlo simulations. Because a large number of photon packets were traced, the variance of the results from Monte Carlo simulations was small enough to reveal the detailed defects of the Diffusion Theory and the similarity relations, which are broadly used in photomedicine. We demonstrated that both Diffusion Theory and similarity relations provide very accurate results when the photon sources are isotropic and buried more deeply than one transport mean free path in turbid media. We found that the key factor affecting the accuracy of the Diffusion Theory application was the conversion from the infinitely narrow laser beam to an isotropic point source in turbid media.
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Analysis of Diffusion Theory and similarity relations for light reflectance by turbid media
Photon Migration and Imaging in Random Media and Tissues, 1993Co-Authors: Lihong V. Wang, Steven L. JacquesAbstract:ABSTRACT Both Diffusion Theory and similarity relations for light reflectance by semi-infinite turbid media have been analyzed by comparing their computational results with Monte Carlo simulation results. Since a large number of photon packets are traced, the variance of the MonteCarlo simulation results is small enough to reveal the detailed defects of Diffusion theories andsimilarity relations. We have demonstrated that both Diffusion Theory and similarity relationsprovide very accurate results when the photon sources are isotropic and one transport mean freepath below the turbid medium surface or deeper. This analysis has led to a hybrid model of Monte Carlo simulation and Diffusion Theory, which combines the accuracy advantage of Monte Carlo simulation and the speed advantage of Diffusion Theory. The similarity relations are used for the transition from the Monte Carlo simulation to the Diffusion Theory. 1. INTRODUCTION In laser-tissue interaction, there is a growing demand for accurate and fast models totheoretically predict the light distribution in turbid media, such as biological tissue, with givenoptical
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hybrid model of monte carlo simulation and Diffusion Theory for light reflectance by turbid media
Journal of The Optical Society of America A-optics Image Science and Vision, 1993Co-Authors: Lihong V. Wang, Steven L. JacquesAbstract:Light reflectance by semi-infinite turbid media is modeled by a hybrid of Monte Carlo simulation and Diffusion Theory, which combines the accuracy of Monte Carlo simulation near the source and the speed of Diffusion Theory distant from the source. For example, when the turbid medium has the following optical properties—absorption coefficient 1 cm^(-1), scattering coefficient 100 cm^(-1), anisotropy 0.9, and refractive-index-matched boundary—the hybrid simulation is 7 times faster than the pure Monte Carlo simulation (100,000 photon packets were traced), and the difference between the two simulations is within 2 standard deviations of the Monte Carlo simulation.
Reindert Graaff - One of the best experts on this subject based on the ideXlab platform.
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practical improvements on photon Diffusion Theory application to isotropic scattering
Physics in Medicine and Biology, 2001Co-Authors: Reindert Graaff, Kees RinzemaAbstract:Based on the analysis of an isotropic point source in an infinite, isotropically scattering turbid medium, we suggest several modifications to the well-known Diffusion Theory. Compared with standard Diffusion Theory these modifications, which require very little extra mathematics, lead to a substantially better approximation of the exact expressions. The improved expression gives reasons to reconsider the basic concept of time-resolved Diffusion Theory.
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Diffusion coefficient in photon Diffusion Theory
Optics Letters, 2000Co-Authors: Reindert Graaff, J.j. Ten BoschAbstract:The choice of the Diffusion coefficient to be used in photon Diffusion Theory has been a subject of discussion in recent publications on tissue optics. We compared several Diffusion coefficients with the apparent Diffusion coefficient from the more fundamental transport Theory, Dapp. Application to point sources in turbid media, for which exact solutions are available, showed that Dapp has to be preferred. We give a simple equation to approximate Dapp for several phase functions that apply to tissue optics. Reasons for the remaining discrepancies in Diffusion coefficients applied to time-resolved and time-averaged descriptions of photon propagation in homogeneous turbid media are discussed.
Lars O. Svaasand - One of the best experts on this subject based on the ideXlab platform.
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characterization of vascular structures and skin bruises using hyperspectral imaging image analysis and Diffusion Theory
Journal of Biophotonics, 2009Co-Authors: Lise Lyngsnes Randeberg, Eivind L P Larsen, Lars O. SvaasandAbstract:Hyperspectral imaging, image analysis and Diffusion Theory were used to visualize skin vasculature and to monitor the development of fresh skin bruises. Bruises were inflicted in a porcine model, and the development of the hemorrhage was monitored using white light hyperspectral imaging (400–1000 nm). Hyperspectral images from human volunteers were also included in the study. Statistical image analysis was used to classify bruised regions and to visualize the skin vasculature. Biopsies were collected from the animals to reveal the true depth of the bruising. A three-layer Diffusion model and an analytic hemoglobin transport model were used to model the reflectance spectra from the images. The results show that hyperspectral images contain depth information, and that the approximate depth and extent of bruises can be retrieved using a combination of statistical image analysis and Diffusion Theory. This technique also shows potential to visualize vascular structures in human skin. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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Performance of Diffusion Theory vs. Monte Carlo methods
Diagnostic Optical Spectroscopy in Biomedicine III, 2005Co-Authors: Lise Lyngsnes Randeberg, Andreas M. Winnem, Rune Haaverstad, Olav A. Haugen, Lars O. SvaasandAbstract:Diffuse skin reflectance was simulated by Monte Carlo methods and Diffusion Theory. Diffusion Theory proved to agree well with measurements, and might in some applications supersede Monte Carlo methods due to faster, more efficient algorithms.
J.j. Ten Bosch - One of the best experts on this subject based on the ideXlab platform.
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Diffusion coefficient in photon Diffusion Theory
Optics Letters, 2000Co-Authors: Reindert Graaff, J.j. Ten BoschAbstract:The choice of the Diffusion coefficient to be used in photon Diffusion Theory has been a subject of discussion in recent publications on tissue optics. We compared several Diffusion coefficients with the apparent Diffusion coefficient from the more fundamental transport Theory, Dapp. Application to point sources in turbid media, for which exact solutions are available, showed that Dapp has to be preferred. We give a simple equation to approximate Dapp for several phase functions that apply to tissue optics. Reasons for the remaining discrepancies in Diffusion coefficients applied to time-resolved and time-averaged descriptions of photon propagation in homogeneous turbid media are discussed.