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Diffuse tomographic imaging after estimation of location and approximate value of the object inhomogeneities through backprojection of the data

Buddhi, Kanmani and Vasu, Ram M (2004) Diffuse tomographic imaging after estimation of location and approximate value of the object inhomogeneities through backprojection of the data. In: SPIE: Coherent Optics of Ordered and Random Media IV: Saratov Fall Meeting (SFM'03), 7-10 October, Saratov, Russia, Vol.5475, 108-114.

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Abstract

We describe here a method for tomographic reconstruction of the optical properties of a diffuse scattering object. The data are the integrated intensity (for absorption coefficient µa) and the mean arrival time (for reduced scattering coefficient µs), obtained from the temporal point spread function (tpsf) measurements. In both the cases we used a nonlinear optimization method to minimize the mean-squared error between the experimental data and the computed data. For computing the forward data, a diffusion equation is used as the model for light propagation. The main contribution of this work is the generation of the approximate location of the inhomogeneity in the object and its approximate value through a simple backpropagation of the data, which are input as a priori known starting information to the iterative reconstruction algorithm. Two advantages follow: (i) with background optical properties assumed to be known, the number of unknowns reduces to those inside the known inhomogeneity, which reduces the dimension of the inversion problem; (ii) initial estimate of the µa or µs values helps to get a quicker convergence to the actual solution. It is shown that without the a priori information from the backprojection algorithm, the inversion either took a much longer time or failed to converge.

Item Type: Conference Paper
Additional Information: Copyright of this article belongs to International Society for Optical Engineering.
Department/Centre: Division of Physical & Mathematical Sciences > Instrumentation and Applied Physics (Formally ISU)
Date Deposited: 24 May 2007
Last Modified: 27 Aug 2008 12:40
URI: http://eprints.iisc.ernet.in/id/eprint/10090

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