Comparison of digital coincidence modules used at POLATOM and PTB for TDCR and 4πß(LS)-γ coincidence counters.

Activity measurements of 3H, 241Am and 60Co solutions were performed to compare digital coincidence modules used at PTB and POLATOM for TDCR and 4πß(LS)-γ coincidence counting. The activities determined with various coincidence modules connected in parallel to the same counter at PTB were found to be consistent. Observed discrepancies caused by differences in the coincidence resolving time did not exceed 0.14%. Accidental coincidences simulated by a frequency generator were registered, and the coincidence resolving time was determined.

A new coincidence module using pulse-mixing method applied in the 4π(LS)-γ coincidence system with TDCR detector.

Application of a new coincidence module using the pulse-mixing method in the 4π(LS)-γ coincidence system with TDCR detector in the beta channel (TDCRG) is presented. The pulse-mixing method extended for the TDCR system with gamma channel was compared with the classical coincidence method where the coincidence resolving time is introduced. The characteristics of the resolving and dead time of the above two methods were investigated. The level of accidental coincidences in the system was determined. The new developed coincidence module was validated by activity measurement of a set of 51Cr, 54Mn, 60Co, 65Zn, 85Sr and 134Cs standards.

Results of an international comparison of activity measurements of 68Ge.

An international key comparison, identifier CCRI(II)-K2.Ge-68, has been performed. The National Institute of Standards and Technology (NIST) served as the pilot laboratory, distributing aliquots of a 68Ge/68Ga solution. Results for the activity concentration, CA, of 68Ge at a reference date of 12h00 UTC 14 November 2014 were submitted by 17 laboratories, encompassing many variants of coincidence methods and liquid-scintillation counting methods. The first use of 4π(Cherenkov)ß-γ coincidence and anticoincidence methods in an international comparison is reported. One participant reported results by secondary methods only. Two results, both utilizing pure liquid-scintillation methods, were identified as outliers. Evaluation using the Power-Moderated Mean method results in a proposed Comparison Reference Value (CRV) of 621.7(11)kBqg-1, based on 14 results. The degrees of equivalence and their associated uncertainties are evaluated for each participant. Several participants submitted 3.6mL ampoules to the BIPM to link the comparison to the International Reference System (SIR) which may lead to the evaluation of a Key Comparison Reference Value and associated degrees of equivalence.

Preparation method and quality control of multigamma volume sources with different matrices.

The aim of the work was to develop new radioactive standard sources based on epoxy resins. The optimal proportions of the components and the homogeneity of the matrices were determined. The activity of multigamma sources prepared in Marinelli beakers was determined with reference to the National Standard of Radionuclides Activity in Poland. The difference of radionuclides activity values determined using calibrated gamma spectrometer and the activity of standard solutions used are in most cases significantly lower than measurement uncertainty limits. Sources production method and quality control procedure have been developed.

Comparison of 131I activity measurements at the NCBJ RC POLATOM and the ENEA-INMRI linked to the BIPM SIR system.

A bilateral comparison between ENEA-INMRI (Italy) and NCBJ RC POLATOM (Poland) of 131I-solution activity measurements was organized in the year 2015 and piloted by POLATOM, which provided the sources for the comparison. The 131I master solution was standardized independently at both institutes by using Liquid Scintillation Counting and ionization chamber techniques. The 131I master solution was then sent by POLATOM to the BIPM International Reference System (SIR). The comparison was registered as an EURAMET.RI(II)-K2.I-131 key comparison allowing the ENEA-INMRI result to enter in the SIR database.

Standardization of Sm-153 solution by absolute methods.

Standardization of (153)Sm by 4π(LS)-γ coincidence and anticoincidence counting and the CIEMAT/NIST method in three LS-counters is presented. This short half-life radionuclide is applied in tumor therapy and bone pain palliation. A simplified disintegration scheme of (153)Sm was applied in the calculation of the counting efficiency. Standard uncertainties of 0.4% for the (153)Sm measurements by the 4π(LS)-γ coincidence and anticoincidence techniques and 0.7% by the C/N method were evaluated, respectively. An agreement of the standardization results by both methods within the respective uncertainties was obtained. The half-life of (153)Sm of (1.92895±0.00024) days was determined during one month of measurements and correction for europium isotope impurities by the C/N method in the TriCarb 2910 LS-counter.

Standardization of a 85Sr solution by three methods.

A (85)Sr solution was measured in two liquid scintillation (LS) counters. Scintillation pulses from the delayed transitions in the (85)Sr decay were by and large lost as the dead time of the LS-counter was much longer than the lifetime of the (85)Rb excited level. The registration probability of these pulses has been defined and introduced into the counting efficiency calculation. The results of the (85)Sr solution standardization by the CIEMAT/NIST and the TDCR methods relative to the results from the 4π(LS)-γ coincidence and anticoincidence method were 0.997±0.012 and 0.971±0.019, respectively.

Results of an international comparison for the activity measurement of 177Lu.

An international Key Comparison of (177)Lu has recently been carried out. Twelve laboratories performed assays for radioactivity content on aliquots of a common master solution of (177)Lu, leading to eleven results submitted for entry into the Key Comparison Database of the Mutual Recognition Arrangement. A proposed Comparison Reference Value (CRV) was calculated to be 3.288(4)MBq/g using all eleven results. Degrees of equivalence and their uncertainties were calculated for each laboratory based on the CRV. Most of the values reported by the participating laboratories were within 0.6% of the CRV.

Comparison of 99Tcm and 131I in Polish hospitals, 2007.

The Radioisotope Centre (RC) has organized for the first time in Polish hospitals a comparison of activity measurements of (99)Tc(m) and (131)I. From the 58 Polish hospitals invited, 37 participated in the comparison. Each participant got about 4 mL of (99)Tc(m) eluate and two (131)I capsules, low- and high-activity. Sources were standardized in the RC before dispatch using a 4pi ionization chamber calibrated by standard solutions. Participants used their own radionuclide calibrators. The measurement results were evaluated using the E(n) criterion and the z'-score. From all 118 measurement results received from participants, 75 results (64%) lay within +/-5% of the RC value, and 99 results (84%) lay within +/-10.0%.