[en] In a scenario of accidental mass radiation exposure transportation and analysis of samples may take some time, resulting in loss of biomarker information over this period. The present study aims to use phosphatase inhibitors for longer retention of focal signals to adopt γ-H2AX as a biodosimetric biomarker for the management of early triage. Peripheral blood lymphocytes isolated from healthy individuals were irradiated in vitro with x-rays and γ-H2AX foci were analysed using fluorescent microscopy and flow cytometric methods. Further, the effect of protein phosphatase 2A inhibitors such as calyculin A, fostriecin and okadiac acid on the retention of foci was studied. Fluorescent microscopy was found to be a more sensitive method than flow cytometry. Calyculin A showed significant retention of focal signals at 6 h with 1.5-fold increased retention compared to radiation alone; this may prove beneficial in early triage management because of a better dose approximation. (paper)