Assessment of Occupational Exposure to External Radiation among Workers at the Institute of Radiotherapy and Nuclear Medicine, Pakistan (2009-2016)

Introduction: Assessment of occupational exposure to external radiation and the analysis of associated trends are imperative to observe changes that have taken place over time due to regulatory operations or technological advancements. Herein, we describe the occupational radiation exposure to workers employed in Nuclear Medicine (NM), Radiotherapy (RT), and Diagnostic Radiology (DR) departments at the Institute of Radiotherapy and Nuclear Medicine, Peshawar, Pakistan, and to evaluate the related trends during 2009-2016. Materials and Methods: A retrospective analysis of the dose records of 4320 film dosimeters was performed during 2009-2016. The analyzed quantities included annual collective effective dose, annual average effective dose, distribution of workers, and their annual average effective doses in various effective dose intervals, as well as the maximum and minimum annual individual effective doses. Results: The annual average effective doses in RT, NM, and DR were within the ranges of 1.07-1.45, 1.25-1.55, and 1.03-1.60 mSv, respectively. The majority (90%) of the workers received effective doses in the interval of 1-4.99 mSv, while 10% of the workers received doses within the range of the minimum detectable level-0.99 mSv.  The minimum and maximum annual individual effective doses were 0.30 mSv and 3.96 mSv as recorded in RT and NM, respectively. The annual average effective doses measured for NM, RT, and DR were 1.39, 1.23, and 1.30 mSv, respectively. These values are comparable with the worldwide annual average effective doses. Conclusion: All the workers received doses below the annual dose limit. The status and trends of doses showed that radiation protection conditions were adequate.