The last decade LaBr3(Ce) scintillation detectors have become commercially available and have better scintillation properties (energy resolution, temperature performance, decay time, light yield and material density) when compared with NaI(Tl) scintillators. The aim of this work is the full calibration (energy, resolution and efficiency) of a 1.5x1.5 in LaBr3(Ce) Canberra scintillator. Energy and resolution calibration were performed experimentally with the use of point sources with a source-detector distance at 22 cm. MCNPX simulations were performed in order to evaluate the efficiency calibration for three different source-detector geometries and then they were validated by the experimental efficiencies estimation.

Sealed radioactive sources of Co-57 and Ge-68/Ga-68 are used for the calibration of various nuclear medicine systems like Gamma camera and PET imaging. After their useful life, these sealed sources need to be kept in control for decay until meeting the general clearance criterion. The aim of this work is to determine the activity of spent sealed radioactive sources of Ge-68 / Ga-68 and Co-57. For this purpose, techniques based on Monte Carlo simulation by the use of the MCNPX code was developed for evaluation of the 3”x3” NaI(Tl) scintillator efficiency for specific source–detector geometries. These techniques proved to be accurate.