New effects of ionizing radiation in the field of small doses of long-term radiation have been opened in recent decades. The difference between the sources of ionizing radiation by type and dose rate leads to a change in the biological response. Dose-effect curves for human dermal fibroblasts (DFH) and cells line Hela were obtained by irradiation cells cultures by β-radiation and X-ray. The viability was assessed using a hemocytometer and MTT test. The characteristics of the biological response and the process of cell regeneration after radiation were evaluated.