Experimental measurements of light scattering from samples with specified optical properties

We have measured the photon intensity transmitted through cylindrical and slab phantoms of different concentration and size scattering particles. Our continuous wave (CW) measurements show quantitatively that the mean cosine of the scattering angle (g) must be taken into account unless the phantoms have very high scattering coefficient. We have compared the results for phantoms made of titanium dioxide in resin, which is commonly used to simulate tissue despite its low g value (0.56), with those for silica in resin phantoms of high g value (0.95). The comparison has shown different angular scattered intensity, both in form and magnitude, for phantoms that have the same reduced scattering coefficient but different g value. The results show that, in some cases, using the reduced scattering coefficient and absorption alone for comparing phantoms or for reconstruction using inverse methods based, for example, on diffusion theory would lead to incorrect interpretations.