Publications [#62277] of Nimmi Ramanujam

Papers Published

1. Palmer, G.M. and Ramanujam, N., Monte Carlo-based inverse model for calculating tissue optical properties. Part I: Theory and validation on synthetic phantoms, Appl. Opt. (USA), vol. 45 no. 5 (2006), pp. 1062 - 71 [AO.45.001062]
   (last updated on 2007/04/13)

   Abstract:
   A flexible and fast Monte Carlo-based model of diffuse reflectance has been developed for the extraction of the absorption and scattering properties of turbid media, such as human tissues. This method is valid for a wide range of optical properties and is easily adaptable to existing probe geometries, provided a single phantom calibration measurement is made. A condensed Monte Carlo method was used to speed up the forward simulations. This model was validated by use of two sets of liquid-tissue phantoms containing Nigrosin or hemoglobin as absorbers and polystyrene spheres as scatterers. The phantoms had a wide range of absorption (0-20 cm^-1) and reduced scattering coefficients (7-33 cm^-1). Mie theory and a spectrophotometer were used to determine the absorption and reduced scattering coefficients of the phantoms. The diffuse reflectance spectra of the phantoms were measured over a wavelength range of 350-850 nm. It was found that optical properties could be extracted from the experimentally measured diffuse reflectance spectra with an average error of 3% or less for phantoms containing hemoglobin and 12% or less for phantoms containing Nigrosin

   Keywords:
   absorption coefficients;bio-optics;biological tissues;calibration;light scattering;molecular biophysics;Monte Carlo methods;phantoms;physiological models;proteins;reflectivity;spectrophotometry;turbidity;