Research On Key Techniques Of Endoscopic Fluorescence Assisted Imaging

In surgery,it is often necessary to locate the location of the tumor boundary and the sentinel lymph nodes around it in order to diagnose whether the cancer cells metastasize and to accurately excise the diseased tissue.Tissues such as sentinel lymph nodes are difficult to distinguish only by the human eyes and need to use fluorescein to help doctors observe.In this paper,a combination of near-infrared and visible light imaging systems was constructed using indocyanine green(ICG)as fluorescein.Previous research efforts have focused only on the fluorescence of indocyanine green,but have neglected the visible light information it contains.The paper has done a fusion of these two images,taking advantage of their respective advantages.The main work of the thesis is:1.Introducing the characteristics of indocyanine green and comparing it with other fluorescent reagents,showing the advantages of indocyanine green in medical imaging.2.Fluorescence imaging system was designed based on the theoretical basis of fluorescence imaging.The system is divided into four main parts: light source,laser transmission component,spectral filtering component,signal detection and processing component.Select the laser as the excitation source,and place a beam splitter 45 °away from the optical path to separate the visible and infrared fluorescence.Then place an infrared filter and a 830 nm narrowband filter in each of the two branches,the role of filtering is achieved.The two lenses behind the two filters capture the visible and infrared images separately and upload the captured images to a computer.3.According to the characteristics of imaging system,the corresponding image processing algorithm is designed.The process of image fusion is divided into four steps:finding feature points,feature point matching,projecting transformation to achieve image registration,and image superposition.The whole fusion process is explained and simulated in detail by using the sample diagram,which verifies the feasibility of the algorithm.4.Experimental study of the excited light phenomenon of indocyanine green in different carriers.The relationship between the fluorescence efficiency and concentration of the indocyanine green aqueous solution was investigated.The stimulating effect of indocyanine green injected into blood vessels was simulated byusing the indocyanine green animal blood solution.A mouse in vivo experiment designed with indocyanine green confirmed that the indocyanine green can be developed in high contrast in vivo.After obtaining the image,the mouse's visible light and fluorescence images were used for fusion processing,which played a key role in highlighting the region of interest,and realized the combination of the advantages of the two.The image resolution after fusion reached 3264×2448.