title: A rapid improved method for gamma-spectrometric determination of 202Tl impurities in [201Tl]-labelled radiopharmaceuticals.
abstract: Despite the cyclotron production method and the efficiency of the radiochemical procedures adopted, the long-lived radio-isotopic impurity 202Tl is always present in [201Tl]-labelled radio-pharmaceuticals, together with other short-lived impurities like, 200Tl. Rapid determination of the 202Tl impurity, can be achieved using HPGe gamma spectrometry and a detector shielded by a 5 mm thick envelope of lead. In this way, dead-time correction errors, Compton and X-ray background, are very efficiently avoided and suppressed. The same method could be applied routinely in nuclear medicine, to determine the radioisotopic purity of 201Tl by means of an ionisation chamber dose calibrator.
authors.affiliation: Radiochemistry Laboratory, Accelerators and Applied Superconductivity Laboratory, Università degli Studi and National Institute of Nuclear Physics, INFN-Milano, Segrate, Italy. mauro.bonardi@mi.infn.it
authors.forename: Mauro
authors.initials: M
authors.lastname: Bonardi
authors.forename: Flavia
authors.initials: F
authors.lastname: Groppi
authors.forename: Claudio
authors.initials: C
authors.lastname: Birattari
mesh_terms: D004340:Drug Contamination; D006801:Humans; D019275:Radiopharmaceuticals / Q000032:analysis*; D012680:Sensitivity and Specificity; D013051:Spectrometry, Gamma / Q000379:methods* / Q000706:statistics & numerical data; D013794:Thallium Radioisotopes / Q000032:analysis*; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D019275:Radiopharmaceuticals; D013794:Thallium Radioisotopes