Features of the diffuse reflection and transmission spectra of normal and tumoral tissues

Method for determining the efficacy of laser photophoresis

“…According to the data in [6][7][8][9], as the radiation wavelength increases from 600 nm to 900 nm, the transmission of biological tissue increases, and accordingly the penetration depth of the laser radiation increases. Most likely, a fairly small amount of energy is consumed to produce the positive effect (from the standpoint of the efficacy of laser photophoresis) of laser radiation on biological tissue, and therefore the deeper the laser penetrates into the biological tissue, the greater the volume of tissue that is exposed to the radiation and the greater the overall effect from the radiation.…”

“…From [6][7][8] and other work, we know that the absorption spectrum of biological tissue can have a local minimum in the 710-800 nm region, mainly connected with the characteristic features of the transmission spectrum of oxyhemoglobin, since radiation with wavelengths in this region is scattered practically identically by different biological tissues. Oxyhemoglobin can be incorporated into biological tissue in a proportion depending on the degree of saturation of the biological tissue with blood, C v , and the degree of saturation of the blood S. Using the model developed by the authors of [6], we calculated the absorption spectra k for the model of a biological tissue for different variations in the tissue oxyhemoglobin content.…”

Optical absorption and scattering spectra of pathological stomach tissues

“…The propagation of light in tissue is determined by its optical parameters, specifically the absorption (μ a ) and scattering (μ s ) coefficients and the scattering anisotropy factor (g). Furthermore, these optical indices contain important information on the micro-and macrostructure of the medium being studied and its constituents, as well as on its physiological, morphological, and biochemical parameters, and are key factors in the solution of basic and applied problems in biotechnology [1][2][3][4][5].Determining the optical indices of biological tissues is an extremely time-consuming task because of the complicated structure of biotissues, themselves, and the variety of ways photons interact with them. Most biological objects, including plant and animal tissue, are optically turbid, randomly inhomogeneous media, for which the scattering index can be hundreds of times the absorption index [1-3].…”

“…The first involves measuring the diffuse reflection coefficient with spatial resolution and analyzing the data in the approximation of a semi-infinite medium with a diffusion or P 3 -approximation for the radiative transfer equations [3,6]. The second approach involves measuring the optical transmission and reflection coefficients assuming media with finite thicknesses and solving the inverse problem for the radiative transfer equations in various numerical or analytical model approximations [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Although the experimental and theoretical approaches are well developed, these methods have a number of well-known and mutually exclusive shortcomings that reduce their information content and practical value [3].…”

“…The propagation of light in tissue is determined by its optical parameters, specifically the absorption (μ a ) and scattering (μ s ) coefficients and the scattering anisotropy factor (g). Furthermore, these optical indices contain important information on the micro-and macrostructure of the medium being studied and its constituents, as well as on its physiological, morphological, and biochemical parameters, and are key factors in the solution of basic and applied problems in biotechnology [1][2][3][4][5].…”