RESUMEN
The Bureau International des Poids et Mesures (BIPM) is developing a new transfer instrument to extend its centralized services for assessing the international equivalence of radioactive standards to new radionuclides. A liquid scintillation counter using the triple/double coincidence ratio method is being studied and tested in the CCRI(II)-P1.Co-60 pilot study. The pilot study, involving 13 participating laboratories with primary calibration capabilities, validated the approach against the original international reference system based on ionization chambers, which has been in operation since 1976. The results are in agreement and an accuracy suitable for purpose, below 5×10-4, is achieved. The pilot study also reveals an issue when impurities emitting low-energy electrons are present in the standard solution, which have a different impact on liquid scintillation counting compared to other primary measurement methods.
RESUMEN
The gamma emitting impurities in 99mTc solution obtained from enriched molybdenum 100Mo metallic target after its irradiation in a cyclotron were measured using a high-purity germanium (HPGe) detector. The radioactivity range of tested samples of 99mTc was rather low, in the range from 0.34 to 2.39 MBq, thus creating a challenge to investigate the standard measurement HPGe system for impurity detection and quantification. In the process of 99mTc separation from irradiated target the AnaLig® Tc-02 resin, Dionex H+ and Alumina A columns were used. Fractions of eluates from various steps of separation process were taken and measured for radionuclidic purity. The overall measurement sensitivity of gamma emitters in terms of minimum detectable activity (MDA) was found at the level of 14-70Bq with emission lines in range of 36 - 1836keV resulting in impurity content range of 6.7 × 10-4 to 3.4 × 10-3 % for 93Tc, 93mTc, 94Tc, 94mTc, 95Tc, 95mTc, 96Tc 96Nb, 97Nb, 99Mo contaminants and 9.4 × 10-3 % for 97mTc. The usefulness of the chosen measurement conditions and the method applied to testing the potential contaminators was proved by reaching satisfactory results of MDAs less than the criteria of impurity concentration of all nuclides specified in the European Pharmacopoeia.
RESUMEN
The standardisation of (111)In by 4π(LS)-γ coincidence and anticoincidence counting is presented. Absolute measurements were performed for samples with different concentrations of carrier solution and for different window settings in the gamma channel. The radioactive concentration of the master solution determined on the same reference date was consistent for all measurements performed. The evaluated typical uncertainty was 0.43%. The half-life of (111)In was determined using a time series of measurements performed with an ionisation chamber. A least squares fit of the measured data resulted in a half-life of 2.8067 (34) days consistent with Decay Data Evaluation Project recommended value (0.064% higher than the DDEP value).
RESUMEN
The Radioisotope Centre POLATOM organized a proficiency test of activity measurements of (90)Y and (89)Sr with nuclear medicine departments in Polish hospitals. Radioactive solutions used in this exercise were standardized by the TDCR method using the measurement systems of the National Standard of Radionuclides Activity in Poland. Results were analysed in compliance with ISO/IEC 17043:2010 (ISO, 2010) by calculating z scores and ζ (zeta) scores. The overall performance of the participants varied significantly. The sources of errors appeared to be the values of the calibration factor used during activity assay and the underestimation of uncertainties by the participants.
