title: X-ray fluorescence analysis (XFA) of thyroidal iodine content (TIC) with an improved measuring system.
abstract: X-ray fluorescence analysis is based on the principal that the electron structure of stable iodine in the thyroid is excited by Americium-241 gamma rays to emit a characteristic fluorescence radiation which is proportional to the amount of iodine present in the gland. A stationary measuring system consisting of a 11.1 GBq Am-241 source and a high-purity Germanium detector with spectrum analyser has been improved by a PC guided method for sonographic definition of the measuring volume. The lower limit of detectibility of the system corresponds to 0.01 mg of Iodine per ml of thyroid volume; the in vivo precision given as coefficient of variation amounts to 15%. The thyroid is exposed with a radiation dose of 6 microSv per measurement. First studies with this improved system carried out in 50 female volunteers between 20 and 40 years of age with normal thyroid volumes resulted in a mean iodine concentration of the thyroid of 0.665 +/- 0.304 mg/ml. The mean iodine excretion in urine was normal with 10.8 +/- 10.4 microg/dl.
authors.affiliation: Clinic and Policlinic for Nuclear Medicine, University of Würzburg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Reiners
authors.forename: H
authors.initials: H
authors.lastname: Hänscheid
authors.forename: M
authors.initials: M
authors.lastname: Lassmann
authors.forename: M
authors.initials: M
authors.lastname: Tiemann
authors.forename: M
authors.initials: M
authors.lastname: Kreissl
authors.forename: J
authors.initials: J
authors.lastname: Rendl
authors.forename: D
authors.initials: D
authors.lastname: Bier
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007455:Iodine / Q000032:analysis* / Q000652:urine; D012680:Sensitivity and Specificity; D013052:Spectrometry, X-Ray Emission / Q000295:instrumentation; D013961:Thyroid Gland / Q000737:chemistry*
chemical_list: D007455:Iodine