ROOM-TEMPERATURE SEMICONDUCTOR-DETECTORS FOR IN-VIVO MONITORING OF INTERNAL CONTAMINATION

In vivo monitoring of low-energy X- and gamma-ray emitters has always been a difficult task, primarily because of lack of accuracy and the h igh detection limits of classical techniques. Various types of PIN dio des (diodes with a large intrinsic zone) were tested in the Radiation Protection Department of the Studie Centrum voor Kernenergie, Centre d 'etude de I'Energie Nucleaire (Mol, Belgium) in the measurement of rad ioactive body burden by direct methods. Current research is oriented t oward the use of room-temperature diodes for the detection of low-ener gy photons escaping the body. In this paper, a new counting technique that involves a portable jacket containing the diodes is described. Th e system uses silicon diodes and is used out of a shielding room in or der to be near the contamination. With this method rapid analysis and long counting times are possible, stress is reduced, and medical treat ment can be optimized. CdZnTe detectors were also evaluated for this m easurement technique but this type of detector is better adapted for c ounting inside a shielding room. The improvement of the accuracy of th e measurement, taking into account the effect of the ribs, is describe d here, as well as the associated electronics necessary for this type of counting.