A versatile and economic whole-body counter based on liquid scintillation detector modules.

A whole-body counter comprising rectangular liquid scintillator detector modules is described. Photomultipliers are used economically and the use of local shielding leads to a further reduction in cost. In conjunction with a moving bed, the modular arrangement provides a versatile system which allows high sensitivity static counting using all detectors, or scan counting using selected combinations of detectors. The total body potassium content of a standard man (140 g K) can be estimated with a statistical counting error of 2.2% in a counting time of 1000 seconds. Methods of using the counter for total body potassium and gastro-intestinal absorption measurements are presented.