Age-dependent efficiency values for standing whole-body monitor

Abstract Standing whole-body monitor (SWBM) at the Integrated Radiation Monitoring Facility is used to measure internal exposure due to fission products for the occupational workers under routine operation. It will also be used to monitor members of the public under radiological emergencies. This is important in mitigating the possible health risks. Calibration of the system is essential to ensure the accuracy of the estimated activity. The whole-body monitors are commonly calibrated using the BOttle Manikin ABsorption (BOMAB) phantom. Monitoring of the public involves different age groups, and efficiency values are dependent on the size of the body. The efficiencies of SWBM for different age groups of the Indian population for whole-body measurement as well as for thyroid measurement are estimated numerically using Indian BOMAB phantoms having uniform distribution. It was found that efficiency decreases as the age increases. Efficiency curve as a function of height, weight, and energy was established to accurately estimate the internally deposited radionuclides for subjects of different age groups. Minimum detectable activities were estimated for various age groups for different radionuclides using these efficiency values. Minimum detectable doses for 137 Cs in the whole body and 131 I in the thyroid are estimated for different post intake period for all the age groups. The results of this work would aid in the accurate estimation of internal exposure for all age groups.