Ga activity calibrations for nuclear medicine applications in Cuba.

The realization and dissemination of the Ga activity measurement unit in Cuba is presented. Firstly, the implementation of the Triple to Double Coincidence Ratio (TDCR) method is described for the calibration of the activity concentration of a Ga solution using a Hidex™ commercial liquid scintillation counter and a FORTRAN code developed for the calculation of the Ga counting efficiencies in the given measurement system. The relative expanded uncertainty (k = 2) associated with the Ga activity concentration obtained with the TDCR method is equal to 2%. With the aim to validate this measurement uncertainty estimate, the method is also applied to an Amersham standard solution of Na - a positron emitter with a similar decay mode to the Ga disintegration scheme from the point of view of type of emitted particles detected in the measurement system. The observed difference between the measured Na activity concentration by the TDCR method and the corresponding reference value traceable to NIST is equal to 0.16%. Outcomes of transferring the Ga activity standard, realized with the TDCR method, to the secondary standard radionuclide calibrator Capintec CRC™ 15R and to three radionuclide calibrators used for Ga PET applications in a hospital are also shown.