Experiments were performed to study the action of fractionated irradiation of mice heads with -rays and protons on their peripheral blood parameters and behavior by the "Open Field" test. Mice were irradiated in two variants of fractionated irradiation: (1) traditional fractionation (in radiation therapy): 2 Gy once a day, 5 times a week, the total radiation dose 20 Gy; (2) extreme hypofractionation: 10 Gy once a week, on Mondays, the total radiation dose 20 Gy. The results of the study showed that irradiation of mice heads has no effect on their peripheral blood parameters in both variants of the applied fractionated irradiation and the behavior of mice does not depend on the type of ionizing radiation and the variant of fractionated exposure that we used. On the basis of these results it can be concluded that the option of extreme hypofractionation we have chosen can successfully replace traditional fractionation, which in some cases is applied when carrying out radiotherapy for treating brain tumors. The application of this type of fractionation can lead to shorter terms of radiotherapy and bigger patient capacity of medical centers that conduct radiotherapy.

Studies have been carried out to test the assumption that the primary photoreceptors for the radioprotective action of 633 nm laser radiation are the cytochrome-c-oxidases. To do this, the device was created for radiation protection of biological objects based on laser module with a wavelength of 532 nm. Experiments conducted on murine fibroblast cells showed that the radioprotection effect of laser irradiation was observed in the dose interval about 0.4-0.85 mJ/cm 2 . Maximum radioprotection effect is observed at laser radiation energy density ~ 0.56 mJ/cm 2 . The determination of the cell survival with the automatic counter СТ20after the action of the ionizing and combined irradiation showed that radioprotective action of the laser radiation with the wavelength of 533 nm, as well as the radiation with the wavelength of 633 nm, is transferred by the mechanism of the "bystander effect". In addition, it was found that radioprotection effect of laser irradiation observed on the criterion of number of surviving single cells, compared with cells exposed to -radiation Laser irradiation, produces effective radioprotecting action also on the criterion of grown cell colonies. The value of the dose modification factor (DMF) calculated on 50% cell survival (LD 50 ) is equal to 1.4. The results suggest that in the case of radioprotective action of small doses of laser radiation with a wavelength of 633 nm, as well as 532 nm primary photoreceptors is the cytochrome-c-oxidases.