Dynamic Diffuse Fluorescence Tomography System And Experimental Research

Dynamic Diffuse Fluorescence Tomography can describe the uptake,distribution and metabolism of fluorescent agents in biological tissues.This technology aims to capture weak and rapidly changing pharmacokinetic information in real time.It has an essential application prospect in early diagnosis and efficacy evaluation of tumor tissues.This paper proposed a dynamic diffuse fluorescence tomography system combining multi-source-detector scheme and lock-in photon-counting technique.Besides,a series of phantom and small animal experiments were designed and conducted to evaluate the system.The system adopted a distribution scheme of 16 source-detection coupled optical fibers evenly distributed around an imaging chamber,which enhanced the spatial sampling density;to achieve simultaneous excitation of multiple light sources,16 laser diodes driven by constant current source can be modulated at different frequency;lock-in photon-counting strategy was proposed to enhance the dynamic performance of the system.A series of phantom and small animal experiments were conducted to evaluate and verify the proposed dynamic system.It mainly includes:(1)the stability of the system was assessed;(2)two schemes including 4-source-4-detector(4 sources excite simultaneously and 4 detectors work in parallel)and 8-source-4-detector were proposed,and the former showed better stability and imaging quality through validating in terms of single channel crosstalk,multi-source stability and static imaging experiments;(3)the results obtained in a series of static and dynamic experiments demonstrated that the imaging performance and the metabolic rate resolution were favorable;(4)the metabolic rate parameters were obtained from the liver metabolism experiments of Indocyanine Green in healthy mice,which proved the ability of the system to capture the fast-changing fluorescence signals in small animals.In conclusion,all above results fully verified the effectiveness of the system and provided a reference for the study of the pharmacokinetics of fluorescence agents in tumor tissues.