⁶⁸Ga activity calibrations for nuclear medicine applications in Cuba

The realization and dissemination of the ⁶⁸Ga 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 ⁶⁸Ga solution using a Hidex™ commercial liquid scintillation counter and a FORTRAN code developed for the calculation of the ⁶⁸Ga counting efficiencies in the given measurement system. The relative expanded uncertainty (k = 2) associated with the ⁶⁸Ga 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 ²²Na - a positron emitter with a similar decay mode to the ⁶⁸Ga disintegration scheme from the point of view of type of emitted particles detected in the measurement system. The observed difference between the measured ²²Na activity concentration by the TDCR method and the corresponding reference value traceable to NIST is equal to 0.16%. Outcomes of transferring the ⁶⁸Ga activity standard, realized with the TDCR method, to the secondary standard radionuclide calibrator Capintec CRC™ 15R and to three radionuclide calibrators used for ⁶⁸Ga PET applications in a hospital are also shown.