<title>Determination of the optical properties of a human brain tumor using a new microspectrophotometric technique</title>

Abstract

We have developed a new technique to determine the optical properties of turbid media on a spatial scale of several 100 micrometers . This technique is based on transmission measurements into three different solid angles using a microspectrophotometer. An inverse Monte-Carlo simulation was employed to extract the optical properties from the sample under investigation. In this study, we investigated the optical properties of human brain tumor tissue. The transmission measurements were performed in the wavelength range from 400 nm to 800 nm for one spot on the sample. In addition, the histological inhomogeneity of the brain tumor was evaluated by probing the optical properties of different spots on the sample at a fixed wavelength. The resulting scattering coefficients varied between 6.0 and 7.9 mm<SUP>-1</SUP>, the absorption coefficients between 0.50 and 0.92 mm<SUP>-1</SUP>, and the anisotropy factors between 0.867 and 0.895. These result suggest that this microspectrophotometric technique is suitable to determine the optical properties of an inhomogeneous turbid media as for example a human brain tumor sample with a spatial resolution unattainable by conventional spectrophotometric techniques.