MONTE CARLO CALIBRATION OF THE WHOLE-BODY COUNTING DETECTION SYSTEM FOR IN VIVO MEASUREMENT OF PEOPLE INTERNALLY CONTAMINATED WITH 90SR.

This work is focused on numerical calibrations of the body counter for in vivo measurement of pure beta emitters through the produced bremsstrahlung radiation. Calibrations were performed using the UPh-02T block whole-body phantom and the Lawrence Livermore National Laboratory (LLNL) realistic torso phantom. Neither of these physical phantoms is appropriate for such calibrations; therefore, specific 90Sr sources have been manufactured to be used with the UPh-02T phantom for experimental measurement followed with Monte Carlo (MC) simulations. Calibrations with the LLNL torso phantom were carried out solely using MC technique. Different scenarios of the 90Sr distribution in the human tissues were considered for the spectrometer calibrations. MC simulations with the LLNL confirmed the applicability of the UPh-02T with specific 90Sr/ 90Y sources for experimental calibrations of the body counters for measurement of pure beta emitters. Differences in count rates in 50-200 keV for UPh-02T and LLNL were not > 25% for all considered scenarios.