Fluorescence of radiation-induced tissue damage

Purpose: The aim of this study was evaluating changes in the photosensitizer fluorescence in vivo in the radiation-induced damage area in comparison of intact areas with a simultaneous assessment of changes both in blood parameters and in histological data. Materials and methods: The study was conducted in white outbred SHK mice (n = 21). Their right hindlimbs were irradiated with a dose of 25 Gy after the intraperitoneal injections of photosensitizer 'Photosens'. Fluorescence intensity was traced in vivo by a laser diagnostic system for seven weeks. Simultaneously, histological examination of the damaged areas and blood tests were performed. Results: An increased intensity of the laser-induced fluorescence of the photosensitizer 'Photosens' in the damaged areas, compared to the intact symmetrical ones was observed. Laboratory blood tests and histological examination showed changes that may indicate the occurrence of inflammation. Conclusion: Enhanced intensity of the exogenous fluorescence of the photosensitizer in the radiation-induced inflammation of noncancerous tissues was observed. The obtained results may potentially affect an interpretation of the results of intraoperative tumors navigation that have been previously irradiated and can be used for selection of an individualized dose fractionation algorithm in radiology.