Modelling elastic scattering and light transport in 3D collagen gel constructs

A model of elastic scattering and light propagation is presented, which can be used to obtain the scattering coefficient, the index of refraction and the distribution of the collagen fibrils in a gel. The model consists of two sections. The first represents the scattering of light by small cylindrical particles, since collagen fibrils can be realistically represented by these structures, and provides the scattering coefficient The second section represents the light transport in multi layered tissues. The output is a diffusive reflectance spectrum. Assuming that a gel is composed of fibrils with the same diameter, it is possible to obtain the input parameters of the model and therefore a simulated spectrum. This can be repeated for several diameters. Considering a gel composed of fibrils with different diameters, it is possible to obtain a best fitting simulated spectrum as weighted sum (least square error based) of the spectra corresponding to several fibril diameters, and therefore obtain an estimate of the percentages of fibrils of each diameter in the gel. Moreover, the scattering coefficient and refractive index, which is also provided by the model, are relevant parameters as they relate to tissue properties in their own right.