A whole-body counter with an invariant response to radionuclide distribution and body size.

The operation and characteristics of the Brookhaven 54-detector whole body counter and its associated computer facility are described. The counter is unique in that it incorporates the following properties: high sensitivity and spectral resolution, relative invariance of counting response to radionuclide distribution and body size of subject, and the ability to provide data on rapidly-translocating short-lived radionuclides. On the basis of the response of the individual detectors to a 'broad-beam' source of 137Cs, it is possible to obtain, empirically, correction factors for geometry and for absorption for each subject. The accuracy and precision of the in vivo measurements performed with this counter are presented for several clinical studies.