Comparative measurements in dose calibrators and a gamma-ray spectrometer.

Specific activity results of (51)Cr, (67)Ga, (99m)Tc and (201)Tl radioactive solutions, measured in different dose calibrators located at nuclear medicine services and in a calibrated HPGe gamma spectrometer, were compared. The HPGe spectrometer was calibrated in a well defined geometry by means of (60)Co, (133)Ba, (152)Eu, (166m)Ho and (241)Am sources, previously standardized in a 4pibeta-gamma coincidence system. Despite the observed differences, the results may be accepted within the 10% uncertainty range, established by Brazilian regulatory standards.