Light-induced fluorescence of human colon tissue: dependence on histological and histochemical properties studied by means of a simplified model for simulation.

Using a spectrophotometer equipped with an internal integrating sphere, the absorption (mu a) and the reduced scattering (mu s') coefficients of ex vivo human colon tissues were evaluated from reflectance and transmittance measurements. mu a and mu-s' varied from 47.7 to 1.0 cm(-1) and from 14.2 to 6.2 cm(-1), respectively, on passing from 300 nm to 800 nm. These results can be used to estimate the optical penetration depths when photodynamic therapy or light-induced fluorescence procedures are used.