Nowadays skin pathology detection on early stages is one of the progressive directions in medicine. Optical diagnostics methods allow to obtain data on skin's structure and composition,to examine biotissue processes without any negative impact on skin. Polarization diagnostics methods are very perspective. They are of interest due to biotissue-scattered optical fields polarization characteristics' high sensitivity to the structural features and physiological status of the study object. Implementation of quantitative ellipsometry in turbid media eventually can provide qualitatively new results with studies of the tissue's morphological and functional state which relate to the most important directions of today medical diagnostics. As a result development of theoretical and practical aspects of optically heterogeneous biological structures and polarized radiation interaction while solving the tasks of non-invasive rapid medical objects' state control is considered to be of current interest for improving of skin formation detection quality. The purpose of this study is to develop a stand for in vivo skin state examination by scattering ellipsometry with a help of studying of anisotropic skin environment influence on the polarization state evolution of the radiation propagating in this skin.The possibility of implementation the method of quantitative ellipsometry for in vivo skin's optical anisotropy and structural heterogeneity studies is shown. The Mueller matrix algebra is used for describing polarization properties of the depolarizing opticallyactive biotissue medium. A setup for recording the polarization state of the backscattered radiation was designed based on a comparative analysis of the technical options and their application in experiments with biotissue. To have a uniform intensity distribution along the cross section of the input radiation beam, and also to form the polarization states necessary for the study, using the emitting channel of the LEF-3 ellipsometer in the optical scheme of the stand is proposed. The choice of the radiation source wavelength in the spectral range (He-Ne laser, 632 nm) is justified, in which radiation scattering in turbid biological media predominates over absorption, which makes it possible to tell about the sample structural parameters by changing output radiation polarization state. The receiving channel of the output polarization state analyzer was designed, which contains based on a color matrix sensor with a unified analysis field video information block, that allows further multispectral studying of the skin surface structure. The method of a skin ellipsometric examination based on the distribution visualization of the polarization state parameters along the cross section of the output radiation beam and on its subsequent analysis is proposed. For image processing and calculation of the sample polarization characteristics an algorithm and software are developed with a Python language. In the backscattering mode of probing laser radiation the distributions of the skin sector containing scar structures polarization characteristics are obtained.
Design of approaches and methods of the oncological diseases diagnostics has special significance. It allows determining any kind of tumors at early stages. The development of optical and laser technologies provided increase of a number of methods allowing making diagnostic studies of oncological diseases. A promising area of biomedical diagnostics is the development of automated nondestructive testing systems for the study of the skin polarizing properties based on backscattered radiation detection. Specification of the examined tissue polarizing properties allows studying of structural properties change influenced by various pathologies. Consequently, measurement and analysis of the polarizing properties of the scattered optical radiation for the development of methods for diagnosis and imaging of skin in vivo appear relevant. The purpose of this research is to design the algorithm of photons migration in the multilayer skin structure. In this research, the algorithm of photons migration in the multilayer skin structure was designed. It is based on the use of the Monte Carlo method. Implemented Monte Carlo method appears as a tracking the paths of photons experiencing random discrete direction changes before they are released from the analyzed area or decrease their intensity to negligible levels. Modeling algorithm consists of the medium and the source characteristics generation, a photon generating considering spatial coordinates of the polar and azimuthal angles, the photon weight reduction calculating due to specular and diffuse reflection, the photon mean free path definition, the photon motion direction angle definition as a result of random scattering with a Henyey-Greenstein phase function, the medium’s absorption calculation. Biological tissue is modeled as a homogeneous scattering sheet characterized by absorption, a scattering and anisotropy coefficients.
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