Evaluation of performance characteristics of portal monitor for radiation emergency

For evaluating the counting efficiency of a portal monitor, we use a137Cs radiation point source (1 μCi) to subsequently establish it effective measurable area. Through simulation, we estimate the appropriate distance from potentially contaminated individuals in the scanning queue to the monitoring individual. When this distance is over 10 m, the counting efficiency was below 0.01%. We find that the triage can be applied to roughly 180 individuals per hour during mass casualties. •We evaluate the performance of a portable portal monitor for radiological triaging.•We evaluate the detector transition area and the effective measurement area.•We determine the “scan-waiting” distance based on experiments and simulations.•The distance between the scanner and patient to be scanned is estimated as 10 m.•Our study can enable rapid triaging for radiation accidents and emergencies.