Simultaneous Imaging System For Singlet Oxygen Luminescence And Fluorescence In Blood Vessels

With the development of vascular-targeted photodynamic therapy(V-PDT)research and clinical application,how to adjust and optimize the dose parameters of V-PDT in real time during V-PDT treatment has become a hot issue.In this paper,a novel simultaneous imaging system for singlet oxygen(¹O₂)luminescence and fluorescence was self-developed,which can simultaneously acquire the information of dose and curative-effect parameters in the region of interesting vessel during V-PDT treatment,such as the ¹O₂ luminescence intensity,the fluorescence intensity,the vasoconstriction,and so on.The information can be applied to study and analyze the correlation between¹O₂luminescence and fluorescence,which effectively avoid the error caused by the time-shared imaging method.The main research contents and innovation of this dissertation are as following:(1)The simultaneous imaging system for ¹O₂ luminescence and fluorescence was designed and developed.The detection unit of this system was composed of the near infrared(NIR)camera for ¹O₂ luminescence imaging and the visible light camera for fluorescence imaging.The vessels in the dorsal skin window chamber of mice from Institute of Cancer Research(ICR)were selected as the study object and the two cameras were placed in two sides of the skin window chamber.The system laser irradiation unit was composed of the continuous wave laser of 532 nm and multi-mode fiber.The light paths of irradiation and imaging were divided by the dichroic longpass mirror(DLP).The system software was developed with Microsoft Foundation Class(MFC),the application program interface(API)of NIR camera,Microsoft Direct e Xtension(Direct X),Open Computer Vision Library(Open CV).The software is composed of some program modules including the display of enhanced image for ¹O₂ luminescence,the display of fluorescence image,the selection of region of interest,the simultaneous sampling,the rapid measurement and so on.It was proved that the self-built system could be applied in monitoring in real time during the V-PDT treatment through the experiment about RB aqueous solution and the vessels in the dorsal window chamber treated by V-PDT.(2)The dose-effect evaluation based on ¹O₂ luminescence intensity and fluorescence intensity,and their correlation were carried out.The images of ¹O₂ luminescence and photosensitizer fluorescence were simultaneously acquired successfully during the V-PDT treatment.The experimental results showed that the lower limit of the laser power density of the simultaneous imaging system was 100 m W/cm² at RB solution of 25mg/kg b.w..In addition,the results also showed that the time-dependent signals of the¹O₂ luminescence intensity and the fluorescence intensity approximately fitted the double exponential function.The average value of correlation coefficient between the two time-dependent signals was greater than 0.8960 in the constricted vessels,which was highly correlated,and was 0.7792 in the vein without vasoconstriction,which was mediumly correlated.The time-dependent signal of vasoconstriction approximately fitted the boltzmann function.The dose-effect relationships of vasoconstriction which changed with the cumulative fluorescence intensity and fluorescence intensity also approximately fitted the boltzmann function,and the average value of correlation coefficient between the two dose-effect relationships was greater than 0.9930,which was highly correlated.(3)A new method of rapid optical clearing with salicylic acid was proposed to reduce the skin background in order to improve the imaging quality of the simultaneous imaging system for ¹O₂ luminescence and fluorescence.This method was suitable for the dorsal skin of ICR mice.Meanwhile,the clearing efficacy of the mice dorsal skin was rapidly judged through the alteration of the gray value in the vascular region.It facilitated the selection of treatment time for V-PDT.The experimental results of the V-PDT treatment combined with the optical clearing method showed that the optical clearing method could effectively improve the imaging quality of the simultaneous imaging system for ¹O₂ luminescence and fluorescence.