Radiation exposure of staff and protection measures at medical applications of β-radiation

Sealed and particularly unsealed beta radiation sources are increasingly used in medicine for radiation therapy. For example, inflammatory joint diseases are treated by radiosynoviorthesis (RSO), i. e. by injecting 90Y, 186Re or 169Er solutions. In vascular brachytherapy 90Sr/90Y, 32P or 188Re are used to cure so-called in-stent-restenosis patients. Recently, the radioimmunotherapy (RIT) of malign lymphoma with 90Y labeled antibodies has been introduced. All these practices are characterized by a high risk of partial body exposures to beta radiation, if radiation protection is not adequately taken into account. Investigations at several workplaces have been performed to estimate the exposure. The skin dose, Hp(0,07), to the hands was measured with thin-layer thermoluminescence detectors (TLD) that were fixed to the fingers of doctors and assistants. Typical values of maximum doses are presented which indicate that the local skin dose to the fingers of the staff can exceed the annual dose limit of 500 mSv. Consequently, adequate protection measures were recommended and investigated. An exposure reduction by one or two orders of magnitude could be observed. Moreover, general problems of routine monitoring of skin exposures with officially authorized extremity dosemeters are discussed. (orig.)