AN IN VIVO STUDY OF THE EFFECTS OF IONIZING RADIATION ON TISSUES BY LASER FLUORESCENCE SPECTROSCOPY

Abstract

Background: Laser fluorescence spectroscopy (LFS) is widely used in various medical areas, oncology being the most known of them. In general, the LFS is used for in vivo diagnostics of tumors. Recent studies have shown that this method could be used for diagnostics of local inflammation, induced by thermal or mechanical injury. It is of interest if LFS could be used for assessment of soft biological tissue injury caused by radiation exposure. Aim: To study fluorescence of an exogenous photosensitizer and its changes over time in the radiation injury area by LFS method in vivo. Materials and methods: The experiment was done in 12 outbred SHK mice whose right hind limbs were irradiated using a gamma-therapy device ROKUS-AM (source, 60Co, at dose of 15 Gy). Before irradiation, the photosensitizer Photosens was administered to all animals intraperitoneally at dose of 2.5 mg/kg. For 21 days fluorescence was assessed in vivo with a laser diagnostic system LAKK-M in the “fluorescence” operation mode, with an excitation wavelength of 635 nm. At days 7 and 21, tissue samples from the irradiated areas of the model animals were studied histologically and differential blood cell counts were assessed simultaneously. Results: The LFS method showed an increase in the accumulation of the photosensitizer in the affected area, compared to an intact contralateral area, with higher signal intensity from the irradiated limb. The changes in the fluorescence signal from the affected over time had two characteristic peaks at days 3 and 14, probably reflecting the stage of local radiation injury. Conclusion: The use of LFS with an exogenous photosensitizer has a potential for a personalized assessment of radiation reactions in radiology.

Keywords

• spectroscopy
• fluorescence
• inflammation
• ionizing radiation
• photosensitizer