Theoretical Study Of The Tissues Reflectance And The Autofluorescence Spectra

Objective:The transportation of laser in human tissues is studied at first,the limitation of diffusion approximation useful tool in tissue optical diagnosing is analyzed using electromagnetic theory and transportation theory. The relation between the tissues diffusion spectroscopy and fluorescence spectra is also studied.Method :The steady state expression of local diffuse reflectance from surface of biological tissues is deduced from diffusion theory computation result is given and compared with the results of Monte Carlo simulation. The intrinsic laser induced auto fluorescence spectra by using reflectance spectra to minimize the effect of the absorption and scattering of tissue. The correlation between studied by Monte Carlo simulation.Result: The establishment of diffusion theory is conditioned. By using a modified expression originated from diffusion theory,which makes it applicable in deducing optical properties of biological tissues from diffuse reflectance measurements. R represents a very good approximation of f for tissues fluorescence spectra correction.Conclusion: The interplay of absorption and scattering can substantially distort the measured fluorescence. In order to extract the intrinsic fluorescence from measured fluorescence, a novel algorithm is given by measuring spectrum of diffuse reflectance. When measured under the same geometry, intrinsic fluorescence can be recovered from measured fluorescence together with diffuse reflectance. More accurate information may be provided with the recovered intrinsic fluorescence.