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.

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One of the main problems of radiotherapy is the lack of selectivity in the absorption of radiation energy by tumor cells due to the similar energy-absorbing properties of tumor and healthy tissues. An increase in the absorbed dose is achieved by introducing or delivering substances to tumor cells with a significantly larger radiation absorption cross-section than in normal cells. The resulting secondary shortrange radiation localizes the energy release near these elements and affects only nearby biological structures. The genotoxic effect of gold nanoparticles on tumor cells of human lung carcinoma A549 under g-gamma radiation was studied. Gold nanoparticles in combination with g-radiation enhance the genotoxic effect on tumor cells A549. g-irradiation in the presence of gold nanoparticles increases the frequency of micronucleus and decreases the proliferative index in A549 cells.

The combined effect of 633 nm laser radiation and 60Co gamma -rays on C3H10T1/2 murine fibroblast cells survival has been studied. A cell monolayer in the wall's surface of the 25 cm2 plastic flasks was irradiated to gamma-radiation and then to laser light in experiments. All the surface of the 5 cm x 5 cm flask's wall or just a 1 cm x 1 cm central part of them has been exposed to laser beam for the bystander effect investigation. 40 minutes after the irradiation cells locating on the surface both of control and all irradiated flasks were dispersed with 0, 25% trypsin solution and seeded for the survival assay. Carried out experiments showed that independent of the size of the surface of the cells monolayer irradiated to laser light, is observed practically the identical radioprotective effect of laser irradiation. . Further investigation of the mechanism of radioprotective effect of the 633 nm optical radiation on fibroblast cells shows that the radioprotective action of the laser radiation is transferred to the fibroblast cells according to the mechanism of the "bystander" effect via direct intercellular communication through gap junctions, as well as via medium transfer from the irradiated with laser radiation ones to non irradiated cell population. The radioprotective action of laser radiation was established also when unirradiated cells were co-cultured as a mixture with irradiated cells.