Determination of the Specifications of the Vienna General Hospital Clinical Whole Body Counter

The whole-body counter in the Department of Nuclear Medicine of the Vienna General Hospital is used for the detection and spectroscopy of small amounts of gamma emitting radionuclides. It represents the type of a Shadow Shild Whole-Body Counter with a scanning device. The patient is placed on a bed and is moved between four 6"x4" NaI(Tl)-detectors with an adjustable sit collimator system. The calibration of the spatial resolution, the energy scale and the efficiency are described as a function of the measured gamma energy. The measurements are made with bottle phantoms, which simulate the absorption and scattering of gamma rays in the human body. Results of the energy calibration and the dead-time limits for high activities are presented. The characteristic quantities like "Minimum Detectable Activity (MDA)" and "Minimum Measurable Activity (MMA)" are determined as a function of the gamma energy of the emitter.