Determination of the concentration of 127I in thyroid tissue by XRF method and NaI(Tl) scintillation detector

The 127I concentration of more than 0.5 g thyroid tissue samples were determined in the concentration range of 0.2-2.0 mg I/g by X-ray fluorescent method. For routine measurements a simple procedure based on NaI(Tl) scintillation detector was elaborated. Because of the poor energy resolution of scintillator detectors, a new evaluation method was established taking into account the corrections owing to the increased background (Compton radiation) because of the exciting radiation and owing to the changes of the volume of the samples. The obtained results agree with those of the usually applied but expensive X-ray fluorescent method using Si(Li) semiconductor detectors. The standard deviation was about 1.5% -suitable for solving the given biological problems. (V.N.)