Results of Intercomparisons Published
Successful participation in intercomparisons and proficiency tests is the key evidence for the technical competence of laboratories. With relevant results, laboratories confirm that their results are comparable with reference values as well as with the results of other laboratories.
In our ISMIS infrastructure group we are taking this into account since long time ago. The first intercomparison measurements with high-resolution gamma spectrometry were performed in the Laboratory for Radioactivity Measurements as far back as 1986. At that time, the radionuclide content in a marine fish meat sample (MA-B-3) and in the lake sediment (IAEA / SL-2) were determined, both intercomparisons being organized by the International Atomic Energy Agency (IAEA) in Vienna.
Over the years, participation in international proficiency tests has become our constant. In addition, our clients, as well as Slovenian accreditation, require the confirmation of our competence through these measurements. Beside performing measurements, suitable providers of comparative measurements must be chosen to cover all the matrices we measure and the radionuclides we determine.
The key quality assessment is the ζ-test:
where ALAB and AREF are the results of laboratory measurements and the reference value, while uLAB and uREF are the corresponding uncertainties with the coverage factor k = 1. If |ζ – test| <2, the results are statistically comparable. Since we trust in our abilities and work, the results of comparison measurements have been published on our website. In addition, our work was presented in lectures at ICRM conferences in 2015 and 2017 and published in the journal Applied Radiation and Isotopes:
- Evaluation of comparison and proficiency test results of gamma ray spectrometry at Jožef Stefan Institute from 1986 to 2014.
- Comparison of intercomparison results of gamma ray spectrometry of spiked and real samples
The figure above shows all the results of comparison measurements of Cs-137 in water samples in the period from 1986 to 2014, different areas of activity are shown on different graphs. In addition, the distribution of ζ-tests in these results is shown - most of the results are between -1 and 1, and all are less than 2.
