Abstract: BACKGROUND ＆ ATM:To study whether the frequency of micronucleated reticulocytes(fMN-Trf-Ret)from human peripheral blood can be used as a biodosimetry to estimate damages caused by radiation. MATERIAL AND METHODS: Nasopharyngeal cancer(NPC)patients were used as models for victims of radiation and their fMN-Ret from peripheral blood were detected after accepting different cumulative doses of radiotherapy using the automatic scoring system for micronucleus test(MNT)based on a single-laser flow cytometer which was established before；cytokinesis block micronucleus test(CB-MNT)was performed to set a standard for comparison. RESULTS: Both the fMN-Ret and the frequency of micronucleated binucleated lymphocytes (fMN-BNLs)of NPC patients were elevated rapidly and sharply after accepting radiotherapy,showing good dose-response relationships；the fMN-Trf-Ret reacted to radiation as the fMN-BNL did. CONCLUSION: The fMN-Trf-Ret from human peripheral blood is a good substitute to the fMN-BNL as a biodosimetry to estimate damages caused by radiation.

Key words: micronucleus testL, flow cytometry, biodosimetry for radiation