Collagen is an endogenous fluorophore that accounts for about 70% of all proteins of human skin, so it can be an optical marker for structural abnormalities in tissues registered by laser fluorescent diagnostics in vivo. Using the examples of such abnormalities as scars, scleroderma and basal cell carcinoma, this study shows the differences between coefficients of fluorescent contrast kf(λ) of abnormalities from the ones for healthy tissues at fluorescent excitation wavelength 360–380 nm. It is shown that scars and dysplasia are characterized by reduced values of kf(λ) for collagen. Due to high turbidity and phase heterogeneousness as well as variation of parameters of blood microcirculation and concentrations of other related chromophores, there is no mathematical model that precisely calculates the concentration of collagen in tissues only with the use of the value of fluorescent signal intensity. So, probably, the best marker of the pathological process is a comprehensive representation of kf(λ) for all endogenous fluorophores, i.e., for all used visible wavelengths. In this case identification of abnormal tissues is quite possible by detecting some deviations of coefficients kf(λ) for the optically identical and symmetrical regions of the human body.

Based on the Kubelka-Munk two-flux model modified by the authors, which makes it possible in one-dimensional problems to obtain exact analytical expressions for radiation fluxes at the boundary of a turbid medium, and Kokhanovsky's solution for the radiation flux of fluorescence, questions are considered of modelling the spectrum of stimulated endogenous fluorescence of biological tissues as applied to problems of noninvasive medical diagnosis. An analytical expression is presented for the spectral distortion function, which depends on the scattering and absorption properties of cellular biological tissues and blood. It is shown that the model spectra agree well with the experimental data.

in experiments with the use of laser fluorescence spectroscopy (LFS) in vivo both for endogenous porphyrin at occlusive ischemia and for exogenous phthalocyanine of aluminum at induced inflammatory processes the enhanced autofluorescence in the red waveband was detected. It means that the LFS in vivo can be an effective tool for the registration of both the ischemic hypoxia and inflammatory processes in clinics.

Over the last 10-15 years a large amount of methods and devices of noninvasive medical spectrophotometry including such techniques as in vivo Laser Fluorescent Diagnostics, Tissues Reflectance Oximetry, Laser Doppler Flowmetry, etc. has been developed and involved in a real clinical practice. In that number several problems of accuracy and reproducibility of clinical diagnostic results have been under discussion as well. But systematic metrological research in this field is still unknown. What dispersions and errors in diagnostic data can be estimated if measurements will be executed on the same object several times, by several doctors with different qualifications or using several devices from both the same and a different manufacturer? In this paper some results of the complex study of errors and uncertainties in diagnostic data caused by using an optical multi-fibers probe are presented. Dispersion and errors up to a level of +/-36,3% for the average registered values were discovered. It is shown that the interactive component of errors caused by interaction of the probe and a surveyed object gives the main contribution to the total uncertainty in diagnostic data.