Research On Imaging And Analysis Methods Of High-resolution Swept-source Optical Coherence Tomography

As a non-ionizing,non-invasive medical imaging mode,optical coherence tomography(OCT)uses the principle of light interference to rapidly scan cross-sectional imaging of optical scattering media such as biological tissue,and can provide micron-scale resolution of living tissue morphology images.Therefore,it is a very attractive technology in the field of biomedical imaging,which was first applied to ophthalmic retinal fundus imaging,and then quickly obtained a wide range of clinical applications,such as the airway wall,esophageal and cardiovascular.At present,the swept source OCT(SS-OCT)system has become a hot spot in the research field of OCT technology because of its point detection advantage of time domain OCT system and fast imaging speed of spectral domain OCT system.This topic analyzes the imaging principle and research progress of OCT technology,and introduces the new imaging method of OCT in detail,the construction and application of high-resolution SS-OCT imaging system,and the OCT image analysis method based on 3D graph search.The research was carried out,and the specific research contents and the results obtained were:1 A high-resolution 1.3um swept-source OCT system was built.The whole system is divided into optical path part,hardware part and software processing part.The optical path portion includes a 1310 nm swept source,a fiber coupler,a sample arm,and a reference arm;the hardware portion includes a balance detector,a galvanometer controller,a data acquisition card,and a computer;and the software processing portion includes algorithms such as the fast Fourier transform,image reconstruction etc.The axial resolution of the constructed system is up to 1.3um.The two-dimensional continuous scanning imaging of the rat brain is performed by using the built-in swept-source OCT system.The imaging results and its three-dimensional renderings show that the performance of the system can achieve the intended design goal.Initially set up a high-resolution swept-frequency OCT system to pave the way for subsequent research.2 In order to make up for the insufficiency of the existing 3D graph search algorithm for OCT images such as the three-dimensional segmentation of OCT images in the airway wall,this paper proposes a three-dimensional processing scheme customized for the tissue segmentation of the airway endoscopic OCT image.The scheme includes image preprocessing that is effective for these images and an adaptive three-dimensional graph search algorithm based on tissue slope.The segmentation result of the proposed method,the segmentation result of the two-dimensional dynamic programming algorithm and the manual segmentation result are respectively reconstructed in three dimensions.The comparison results show that the segmentation result of the method is more continuous,more robust and closer to the manual segmentation gold standard.3 Using the built-up high-resolution 1.3um swept source OCT system to conduct a preliminary measurement of the solid stress of malignant tumors,and obtain the deformation before and after the complete tumor destruction by OCT imaging system,and then based on the finite element method use the spring mathematical model to calculate the spatial distribution of solid stress within the tumor from the strain of the tumor and the mechanical properties of the tumor,such as elastic modulus and Poisson's coefficient.The experimental scheme of tumor solid stress measurement suitable for OCT imaging mode was designed.The theoretical basis of the stress obtained by deformation was deduced and the finite element simulation experiment reflecting the stress-strain relationship was completed.