Study of Biological Effects by Pulsed Bremsstrahlung Radiation of Ultrahigh Dose Rate at the Angara-5-1 Facility

Radiological methods of treatment of malignant tumors are widespread in medical practice. In addition to the type of radiation and dose and fractionation of the radiation regime, the dose rate is one of the factors that affects the effectiveness of treatment. The therapeutic dose rate lies in the range of tens of mGy/s. At modern high-current accelerators of relativistic electron beams, a significant increase in the dose rate to hundreds of MGy/s is achievable, which is more than 10 8 times greater than the therapeutic dose rate. It is difficult to predict the nature of processes in tissues and its cells at such radiation intensities. To determine the effect of extreme dose rate on the radiosensitivity of tissues at the Angara-5-1 facility, experiments were conducted to determine the lethal dose (LD50/30) for laboratory mice. Our result on the study of the LD50/30 dose (~100 MGy/s) allows us to make a conclusion about a possible higher lethal dose than the power range of the doses used for medical purposes.