Autori: E. L. Grigorescu, C. D. Negut, A. Luca, Anamaria Cristina Razdolescu, Mioara Tanase
Editorial: Applied Radiation and Isotopes, 60, p.429 - 431, 2004.
The radionuclide Ga-68 is mainly a positron emitter (89.2%), with a half-life of 67.7 min. It is used in nuclear medicine, being chemically extracted from the mixture (68)(Ge + Ga); its precursor, Ge-68, disintegrates 100% by electron capture, with a half-life of 270.8 d (Table of radionuclides, comments and Evaluation).
A 4pibeta-gamma coincidence method was used for standardization, with a 4pi proportional beta-detector and a NaI(Tl) gamma detector. Registration of the capture radiations was avoided using foil absorption and a high beta threshold. Using supplementary foils for positron absorption, extrapolation graphs were obtained, with a mean slope of -4.4%. Care was taken to compensate for the loss of Ge-68 during the preparation of solid sources for measurement. A combined uncertainty of 1.1% was estimated.
Cuvinte cheie: absolute activity measurement, coincidence method, Ge-68, Ga-68