Optical properties and chromophore concentration measurements in tissue-like phantoms

Abstract

Biomedical laser light dosimetry relies on spatial light distribution measurements in combination with the appropriate laser–tissue interaction model that may be used to determine the tissue optical coefficients and the fluorophore concentration from its fluorescence spectra. Therefore, modelling of light transport in tissue, for optimization of laser dosimetry, requires the development of simple theoretical models and the experimental implementation in tissue-simulating phantoms, with known optical and fluorescence properties.Low cost phantoms were used, based on agar dissolved in water as the transparent matrix. The latter is loaded with various amounts of Intralipid and fluorophores as light scatterer and absorbers, respectively. The optical properties of these phantoms were measured at two different visible wavelengths.By comparing the fluorescence emission spectra of the turbid samples containing the same fluorophore in different concentrations, we can calculate the concentration. In addition, the evaluation of the scattering and absorption coefficients allow us to predict the spatial distribution of the light intensity inside and outside of the phantom.It seems that the Monte Carlo simulation is an effective and relatively simple mathematical approach for tissue optical properties evaluation.