Patent attributes
A method of determining a quantity of a first radioisotope in a source term, disintegrating into a second radioisotope, the radioisotopes respectively emitting first and second gamma rays screened by the source term, the method comprising the steps: a) determining the theoretical ratio of counts between the first and second rays emitted in the absence of screening; b) measuring the net counts associated with the first and second rays emitted by the first and second radioisotopes; c) determining the screening rates of the first and second rays by the source term based on the ratio obtained in step a) and the counts obtained in step b); d) determining the quantity of the first radioisotope based on the screening rate of either the first or the second ray determined in step c).