Equivalent relative biological effectiveness for cell survival and micronuclei formation; Insights from a biophysical approach

Matsuya, Yusuke  ; Saga, Ryo*; Wang, Y.*; Sato, Tatsuhiko   

Radiation-induced micronuclei (MN), which are chromosome fragments, are currently used as a quantitative indicator of the chromosomal aberrations detectable at a relatively early phase. The technique to assay the MN formation has been followed with increasing interest. However, the meaning of MN and the corresponding cellular responses remains uncertain. This study presents a biophysical model for estimating MN frequency by the extension of an integrated microdosimetric-kinetic (IMK) model that allows the prediction of cell survival after exposure, and theoretically explores the cellular responses associated with MN formation. By introducing a probability of MN formation from lethal lesions due to misrepair, our developed model enables the prediction of MN formation frequency depending on linear energy transfer and dose rate. Our model analyses confirmed that the relative biological effectiveness for cell survival and MN frequency are equivalent under the same irradiation conditions, indicating that MN is useful in both radiation therapy and radiation protection to quantitatively evaluate curative effects and histological damage at early stages after exposure.