Abstract: There is a dose-rate effect between the chromosome aberrations and ionizing radiation in the low Linear Energy Transfer. To better estimate the biological dose absorbed under different dose rates, human peripheral blood was irradiated by X-rays in three different irradiation dose rates. CA was used to induce premature chromosome condensation, and then counted the chromosome fragments rate of the specimens by blind reading. To analyze the relationship between chromosome aberration rate and irradiation, we established the dose-response curves and mathematical model in different dose rates. Results show the aberration frequency increases with the absorbed dose when the dose rate is constant; and the aberration frequency increased with dose rate wthen the absorbed doses are the same. There is a notable dose-rate effect observed. Considering the dose-rate effect, approximate dose-rate dose-response curve should be chosen to estimate the absorbed dose in low linear energy transfer.

Key words: premature chromosome condensation, chromosome aberration, dose-effect relationship, dose rate