Evaluation on the Counting Efficiency of a Chair-type Whole Body Counter for Accident Monitoring of Internal Contamination

Major accidental release of radionuclides has the potential for significant radiation exposure in large populations.[1] Rapid monitoring for internally contaminated people is required in radiation accident. If the release contains radionuclides which emit high energy gamma ray, the most suitable mean of providing this monitoring is Whole Body Counter(WBC).[2] Chair-type WBC is more suitable than other geometry at the scene in the vicinity of radiation accident.[3] Traditionally, BOttle Mannkin ABsorber(BOMAB) phantom has been used for calibration of the WBC.[4,5] In this study, evaluation on the counting efficiency of the chair-type WBC was performed to effectively calibrate the system. Counting efficiencies were obtained by using Monte Carlo simulation and conventional calibration experiment. It was reported that the purchase and use of a BOMAB phantom family can be both expensive and time consuming.[4] However, Monte Carlo simulation is an alternative to obtain the counting efficiency of the chairtype WBC. The counting efficiency by Monte Carlo simulation was compared with experimental data. The aim of such a comparison is to provide inexpensive alternative for conventional calibration procedure and to develop more convenient and accurate calibration method.