Chromosomes are observed during the mitotic phase of the cell-cycle. As organisms have a species-specific chromosome number and morphology, any changes in the number or morphology can be considered as chromosome aberrations. It is well known that radiation exposure causes chromosome aberrations, and multiple studies have reported on the mechanisms of radiationinduced chromosome aberrations and the effects of radiation dose and quality on chromosome aberrations. Radiation-induced chromosome aberrations can be divided into 2 categories: stable chromosome aberrations which are inherited by daughter cells in cell division (e.g. translocations, inversions, partial deletions and duplications) and unstable chromosome aberrations which cause cell death and eventually disappear (e.g. dicentrics, rings and acentric fragments). In acute external exposure, unstable chromosome aberrations are usually used as indicators for accurate dose assessment to facilitate radiation emergency medical care. On the other hand, stable aberrations are generally used for retrospective dosimetry caused by past exposures. This article summarizes the essential information on chromosomes and chromosome aberrations for cytogenetic biodosimetry.
