The standardization of Lu-177 by 4 pi ss liquid scintillation spectrometrywith H-3-standard efficiency tracing

Solutions containing the potential radiotherapy radionuclide Lu-177 have be en standardized at the National Institute of Standards and Technology (NIST ) by 4 pi beta liquid scintillation (LS) counting with H-3-standard efficie ncy tracing using the CIEMAT/NIST method. Confirmatory measurements were ma de with 4 pi NaI(Tl) gamma -ray spectrometry. Activity determinations were made on 4 solutions over the course of 10 months with an expanded (k = 2) u ncertainty on the activity of 0.8%. Half-life measurements were carried out using the NIST "4 pi" gamma ionization chamber (IC) and LS counting and ga ve a new value of 6.65 +/- 0.01d, which is shorter than the current ENSDF-r ecommended value bq 1.3%. Impurity analyses were performed by high-purity g ermanium (HPGe) gamma -ray spectrometry and indicated only the presence of Lu-177m at a level of 0.02% that of the Lu-177 as of the respective referen ce times: for the four solutions. Calibration factors fur the NIST IC and V inten 671 ionization chambers were developed, as were dial settings for the NIST-maintained Capintec CRC-12, Published by Elsevier Science Ltd.