Elementanalys Almen & Gronberg Ab

Thomas Gronberg

Klaes Golman

Torsten Almen

Staffan Sjoberg

Soren Mattsson

An apparatus for determining the content of an element having an atomic number higher than 47, in a sample volume, in particular for determining the concentration of an X-ray contrast agent in vivo, employs a radiation source for such excitation of the element in the sample volume with collimated radiation that the element emits its characteristic X-ray radiation. An NaI(T1) scintillation detector is directed towards the sample volume for receiving X-ray radiation therefrom at an angle of from 90.degree. to 135.degree. in relation to the excitation radiation. Both the energy of Copton-scattered photons in the sample and the difference between this energy and 28.5 KeV must be clearly distinguished from the characteristic energy of the element concerned. A first single-channel analyzer registers the number of pulses of the detector within a predetermined energy interval about the energy value for the characteristic X-ray radiation of the element concerned, and two further single-channel analyzers register the number of pulses at the limits of the interval mentioned. A calculating unit in the form of computer determines the background radiation in the interval mentioned using the two latter pulse numbers, and determines the content of the element concerned from the difference between the pulse number of the first analyzer and the pulse number representing the background radiation.

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Sodra Sandby, Sweden

Thomas Gronberg