ASSESSMENT OF EXPOSURE OF WORKERS TO IONIZING RADIATION FROM RADIOIODINE AND TECHNETIUM IN NUCLEAR MEDICINE DEPARTMENTAL FACILITIES

Background: Due to its use of ionising radiation, the field of nuclear medicine is a unique and significant part of medical diagnostics and patient treatment. The aim of this study was to assess the internal exposure of nuclear medicine employees to radioiodine I-131 and technetium Tc-99m as well as to assess the external exposure doses. Material and Methods: The radioiodine I-131 and technetium Tc-99m contents in the thyroid of staff members (about 100 persons) dealing with these radionuclides have been measured in four department of nuclear medicine. The measurements were conducted with a portable detection unit for in situ measurements of radioiodine and technetium. High sensitivity environmental thermoluminescent dosimeters (TLD) were used to measure the external exposure dose. Results: The average values and ranges of radioiodine I-131 activity measured in the thyroids of all of the medical units' employees were: 83 Bq (range: 70-250 Bq), 280 Bq (range: 70-4000 Bq), 275 Bq (range: 70-1000 Bq) for technical staff, nuclear medicine staff and hospital services staff, respectively. The mean value of technetium Tc-99m content in the thyroids of nuclear medicine staff was approximately 1500 Bq (range: 50-1800 Bq). External exposure dose rates were in the range of 0.5-10 mu Gy/h. Conclusions: The calculated average effective dose for particular person caused by the inhalation of radioiodine I-131 is below 5% of 20 mSv/year (occupational exposure limit).