A joint HML-KAERI project--comparison of the LLNL and JAERI torso phantoms using four 50 mm Ge detectors

The Health Physics Department of the Korea Atomic Energy Research Institute and the Human Monitoring Laboratory have collaborated to compare the LLNL and JAERI torso phantoms. The counting efficiencies of the phantoms at 17.7 keV, 59.5 keV, 121.8 keV, and 344 keV were measured with KAERI's germanium lung counting system. The data were made comparable by converting the chest wall thicknesses and adipose mass fractions of the phantoms to muscle equivalent chest wall thicknesses. The counting efficiencies of the two phantoms are within 12% to 17% of each other at 17.7 keV, 15% to 22% at 59.5 keV, 10% to 15% at 121.8 keV, and 7% to 10% at 344 keV. This joint study has shown that the LLNL and JAERI phantom are essentially equivalent for the purposes of calibrating a lung counting system that consists of two ACTII germanium detectors.