Use of the reference source method to determine the half-lives of radionuclides of importance in nuclear medicine

The reference source method associated with HPGe γ-ray spectrometric techniques has been applied to half-life determinations of radionuclides used in nuclear medicine. Simultaneous measurements were undertaken for radiopharmaceutical nuclides such as 67Ga, 99Tcm, 123I, 131I and another radionuclide as reference. Besides optimizing the analysis time, this procedure was shown to be independent of the instrumental technique, environmental and radiochemical impurity interferences for most radionuclides. However, some restrictions were observed in samples that contained impurities with the same emission energy or an energy that was very close to the energy of the radionuclide to be measured. The measurement conditions improved the quoted accuracy of the half-life by reducing the type B component uncertainty.