Plan for the construction of a total body radioactivity counter using gamma spectrometry

A survey of the importance of total-body radioactivity counters for medicine is presented together with a plan for the construction of such an apparatus at the University de Liege. Measurements are made by use of gamma spectrometry, which permits qualitative scanning at the same time as a quantitative determination of many radioisotopes. A plastic scintillator made from plastifluor blocks surrounding the patient was adopted. The detector is a cylinder of 50-cm dia. and 1.60- to 1.80-m lengih. The shield surrounds the counting chamher and is usually completely closed. The shield is made of laminated steel plates, 15 to 20 cm in thickness. The electronic systems consist of one or more photomultipliers and an impulse selector. The counters will have three main applications: determination of total K in vivo, control of either natural or accidental radioactive contamination, and investigation of tracers used in very small doses. This apparatus does not offer full discrimination between various isotopes, but it satisfies many analytical clinical needs. (BBB)