SECURITY OF RADIOACTIVE MATERIALS FOR MEDICAL USE

Both sealed and unsealed radioactive sources are used in hospitals throughout the world for diagnostic and therapeutic purposes. High activity single sealed sources are used in teletherapy units, although these are becoming less common as they are replaced by linear accelerators, and in blood irradiator units, which are in widespread use. Lower activity sealed sources are used in brachytherapy. High activity unsealed sources are used typically for the treatment of thyroid cancer and neuroblastoma in inpatients while diagnostic doses of unsealed radioactive materials have much lower activities. In the case of a central radiopharmacy producing patient doses of radiopharmaceutical for several Nuclear Medicine departments, however, quite large amounts of radioactive materials may be held. Hospitals are, by their nature, less secure than other licensed nuclear sites and the ever-changing patient/visitor (and staff) population is a further complicating factor. Hitherto, security of radioactive materials in hospitals has tended to be considered from the perspective only of radiation safety but this approach is no longer sufficient.