Monitoring of occupationally exposed workers in a PET-centre

A PET-Centre is jointly run with the technical university Dresden (TUD) at the research location Rossendorf. The deployed, short-lived positron emitters are also produced on the location. Apart from the medical applications extensive research projects take place. Workers in this area are occupationally exposed. About 35 persons which are directly involved in the production, processing and application of the radioactive substances, are monitored by official film dosimeters organised by the department of radiation protection-person / Incorporation Surveillance Station. In addition to the workers from the research centre, those operating in the PET-centre of the TUD are routinely monitored by means of operational, self-reading dosimeters, partial-body dosimeters (hands) and incorporation surveillance. The corresponding working areas require well adapted monitoring methods. While direct radiation is the main contributor to the exposure during the production process in the PET-Cyclotron (film dosimeter values), the main attention during the processing and application has to be focussed on partial-body exposure. Investigations on the local distribution of exposure confirmed a conversion factor 2 between dosimeter location and site of greatest exposure as derived in former in previous investigations. Continued repeated operations can cause exposures close to the dose limit of 500 mSv for the hands. According to experiences up to now, incorporations (determined both by random measurements and measurements after interventions, semi-annually at the accelerator) will cause negligible contributions to the exposure in the routine operation. (orig.)