RECONSTRUCTION OF IN-VIVO SKIN AUTOFLUORESCENCE SPECTRUM FROM MICROSCOPIC PROPERTIES BY MONTE-CARLO SIMULATION

The in vivo skin autofluorescence spectrum was reconstructed by Monte Carlo simulation using microscopic fluorophore distributions and intri nsic fluorescence spectra measured from excised skin tissue sections a s well as employing published skin tissue optical parameters. The theo retical modeling took into account the light-tissue interactions of sc attering, absorption, and regeneration of fluorescence photons, The mo dification of the intrinsic spectra by tissue optical properties to ge nerate the in vivo spectrum observed at the tissue surface can be repr esented by a fluorescence detection efficiency function (eta) which eq uals the integral of the product of the excitation fight distribution inside the tissue and the fluorescence escape efficiency. Comparison o f the reconstructed in vivo spectrum with the measured spectra showed good agreement, outside of the blood absorption bands, suggesting that (i) the theoretical modeling, (ii) the skin optical parameters used, and (iii) the measured microscopic morphology and spectral data are co nsistent. The divergence which exists over the strong blood absorption wavelength band (530 - 600 nm) suggests that the effect of blood cont ents on in vivo tissue optical properties deserves further investigati ons.