Comparisons of activity measurements with radionuclide calibrators—A tool for quality assessment and improvement in nuclear medicine

A national program of ongoing comparisons for assaying gamma-emitting radiopharmaceuticals for amount of radioactivity using radionuclide calibrators was begun in 2000. Nuclides of the most wide-spread use in Cuban nuclear medicine, 131I, 201Tl and 99mTc, as well as two measurement geometries, glass vials and plastic syringes, were employed. In this paper, the participants’ performance is assessed by mean of a statistical analysis of the reported data. Performance tables have been obtained and a χ2 statistic is calculated from observed and expected frequencies, with the aim of testing the hypothesis about the independence of some characteristics of the comparison results, at a significance level α=0.05. The proportion of satisfactory results in the years 2002–2004 were found to be at the same level, but higher than in 2000. It reveals an improvement of the measurement quality since 2002. The causes of improvement were investigated using the statistical treatment of several data available as supplementary information.