Study On Light Scattering Characteristics And Diffraction Imaging Of Human Cells

In the field of biomedical engineering and clinical science,the recognition of cell morphology and internal structure can be effectively used for the prediction,diagnosis and efficacy of various diseases.The biological cells can be regarded as an electric dipole array formed by electromagnetic wave stimulation under the illumination of a highly coherent light source.Due to the heterogeneity of the distribution of intracellular optical parameters,light scattering becomes the predominant form of light propagation.The spatial distribution of this scattered light is superimposed by the coherent scattered light generated by the dipole array and highly correlated with the change of the overall shape and internal structure of the cell,therefore,it contains abundant cell morphology and structural information and can be widely used in the study of cell health and cancer.Current approaches like the traditional flow cytometry and fluorescence microscopy flow cytometry are unable to extract three-dimensional information of cell or measure automatically and quickly,and also fluorescent staining is required during cell function detection.we herein used coherent light stimulate single cell to collected co-polarized diffraction image(p-DI)pairs formed by scattered light,investigated the effect of cell morphology and refractive index distribution on p-DI pairs,and illuminated the relationship between the three-dimensional structure of cells and the characteristics of p-DI.We not only completed the theoretical modeling and simulation,but establish a Cell Polarization Diffraction Experiment Platform,using the real human prostate cancer cells and normal cells to identify cancer cells and normal cells within a large scattering angle range.The main contributions of this thesis are listed as follows: First,advanced the 3D reconstruction and structural analysis of the confocal image,segmented the organelles such as the nucleus,cytoplasm and mitochondria from the cells.Second,improved the optical cell model,divided the overall structure of the cell into multiple units,and each unit was given a corresponding refractive index.Third,according to the theory of discrete dipoles,we written a general program,which can represent different cell morphology and internal structure in the Linux environment and explain the causes of different scattering spectra.Fourth,discussed the simulation method of cell diffraction imaging,and obtained the diffraction images of different cells,different cell orientations and refractive index distributions.Fifth,the Gray Level Co-occurrence Matrix(GLCM)algorithm is used to quantify the measured and calculateddiffraction image texture;The dependence of GLCM parameters extracted from cell diffraction patterns on cell morphology and refractive index distribution was analyzed by constructing various cell optical models of different cell structures;Through quantitative comparison of p-DI data,it is proved that cells can be detected accurately,rapidly and without label by single-diffraction imaging technology,and the feasibility of the follow-up study is also presented.