ABSTRACT
The influence of the LS-cocktail on the value of the ionisation quenching kB factor was investigated. Sets of 3H and 63Ni standard sources in some commercial and home-made scintillators of different compositions were prepared and measured using the TDCR method. The Birks kB factor was determined for each LS-cocktail and the results are discussed. A model of anisotropy of the triple counter caused by PM-tubes defocusing was applied for calculation.
ABSTRACT
99mTc is a widely used nuclide in nuclear medicine for diagnosis. 99mTc solutions are eluted from 99Mo/99mTc generators as sodium chloride solutions. As the 99Mo source is a fission product extracted from the reprocessing of nuclear fuel, one might expect the presence of radioactive impurities. One point of special concern described in the 1997 European Pharmacopoeia (1996) is the possible contamination in alpha-impurities (U, Pu, Am, Cm, ...) which must be very low. In order to check this impurity concentration, we used liquid scintillation counting (LSC) with alpha/beta discrimination and a commercial extractive scintillator, Alphaex. We first made measurements using synthetic mixtures of alpha and beta-emitters and then using the real effluent. This paper describes the measurement procedure used with the optimum chemical conditions for a correct extraction of the alpha-emitting nuclides. The sensitivity of the method is also described from the measurements made using the real effluent with an addition of a quantitative amount of alpha particle contamination.
Subject(s)
Radioisotopes/analysis , Biological Science Disciplines/methods , CalibrationABSTRACT
Detection efficiency variation is often used in liquid scintillation counting in order to evaluate a parameter in the detection efficiency calculation model. The aim of this paper is to compare the effects of three different detection efficiency variation methods in the activity measurement of three pure-beta radionuclides: 3H, 63Ni and 14C. Some general conclusions concerning the TDCR method are drawn.
