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Proceedings Paper

Towards optical characterization of biological media: analysis of backscattered images in linearly polarized light, simulations and experiments
Author(s): Julie Falconet; Raphaël Sablong; Franck Jaillon; Emmanuel Perrin; Hervé Saint-Jalmes
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Paper Abstract

Optical imaging is a non invasive way to characterise turbid media, which is of real interest for investigating biological tissues for diagnosis purposes. A method called Integral Reflectance (IR) has already been developed [1]. The media being illuminated by a laser beam (670 nm, <1 mW), the backscattered light is captured by a 2D CCD camera. The reduced scattering coefficient μ's and the absorption coefficient μa are determined from the image. Having μ's and μa, the objective is to improve the characterization by estimating the anisotropy factor g, using polarized light. Different patterns depending on g are produced in these images, presenting some lobes, centred in the entry point of the laser beam, whose number and shape vary with g. To assess a simple description of these patterns, a circular outline of the image, at a given radius, is studied by Fourier series decomposition, namely Fourier descriptors, whose indices, modulus and phase provide the number, the size and the orientation of the lobes, respectively. Backscattered images of turbid media with g in the range [0.006 ; 0.93] (μ's = 10, 20, 40 cm-1 ; μa = 0.01, 1, 5 cm-1), were simulated using a Monte Carlo code for polarized light. Tables of Fourier descriptors were obtained as function of g, μ's and μa. Five reference solutions made of polystyrene spheres in liquid, with g varying from 0.71 to 0.919 (tissue phantoms) were tested. The Fourier descriptors were compared to simulations, and g could be retrieved with a maximum error of 10%.

Paper Details

Date Published: 23 September 2005
PDF: 11 pages
Proc. SPIE 5959, Medical Imaging, 59590I (23 September 2005); doi: 10.1117/12.621375
Show Author Affiliations
Julie Falconet, CNRS, Univ. Claude Bernard Lyon I (France)
Raphaël Sablong, CNRS, Univ. Claude Bernard Lyon I (France)
Franck Jaillon, CNRS, Univ. Claude Bernard Lyon I (France)
Emmanuel Perrin, CNRS, Univ. Claude Bernard Lyon I (France)
Hervé Saint-Jalmes, CNRS, Univ. Claude Bernard Lyon I (France)

Published in SPIE Proceedings Vol. 5959:
Medical Imaging
Andrzej Kowalczyk; Adolf F. Fercher; Valery V. Tuchin, Editor(s)

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