Impurities in Tc-99m radiopharmaceutical solution obtained from Mo-100 in cyclotron.

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.

(90)Y microspheres prepared by sol-gel method, promising medical material for radioembolization of liver malignancies.

A new technology for the production of radiopharmaceutical (90)Y microspheres in the form of spherical yttrium oxide grains obtained by sol-gel method has been described. The authors present and discuss the results of investigations performed in the development of new production technology of yttrium microspheres and determination of their physic-chemical properties. The final product has the structure of spherical yttrium oxide grains with a diameter 25-100µm, is stable and free from contaminants. Irradiation of 20mg samples of grains with diameter of 20-50µm in the thermal neutron flux of 1.7×10(14)cm(-2)s(-1) at the core of MARIA research nuclear reactor allowed to obtain microspheres labelled with the (90)Y isotope on the way of the nuclear reaction (89)Y(n, ɤ)(90)Y. Specific activity of irradiated microspheres has been determined by application of absolute triple to double coincidence ratio method (TDCR) and has been evaluated at 190MBq/mg Y. (90)Y microspheres prepared by the proposed technique can be regarded as a promising medical material for radioembolization of liver malignancies.

Radionuclidic purity tests in (18)F radiopharmaceutIcals production process.

Radionuclidic purity tests of (18)F radiopharmaceuticals (Na(18)F and fluorodeoxyglucose [(18)F]FDG) and radionuclide composition analysis of irradiated water [(18)O]H2O were performed. The measurements were conducted using a High-Purity Germanium (HPGe) detector and a liquid scintillation counter. Radionuclide identification and activity measurements were performed for samples from different stages of the production process. Most of the impurities were detected on QMA (quaternary methylammonium) anion exchange columns and in liquid wastes. Using liquid scintillation counting, the activity of (3)H resulting from the (18)O[p, (3)H](16)O reaction was determined. It was shown that all of the impurities were efficiently determined and eliminated in the radiopharmaceuticals synthesis process and that the final products meet the requirements set by relevant regulations.

Standardisation and half-life measurements of (111)In.

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).

Proficiency test of 9°Y and 89Sr activity measurements in Polish hospitals.

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.

Determination of 90Sr traces in medical 90Y after separation on DGA column.

A new analytical procedure for (90)Sr determination in freshly milked (90)Y from a (90)Sr/(90)Y generator is described. To a solution containing 125 mg of Sr a 200 to 400 MBq sample of (90)Y is added and strontium is separated from (90)Y using DGA column of 1 mL volume. (90)Sr is recovered in a yield close to 100% and counted in a liquid scintillation spectrometer (LSC). The separated strontium is slightly contaminated with (90)Y in the range from 7 to 19% of (90)Sr activity. The separation and counting can be completed within 30 min. The detection limit in 900 s counting time is equal to about 0.2 Bq. This corresponds to (90)Sr/(90)Y activity ratio of 10(-8) level.