Optimization in open fixed gammagraphy facilities

To determine optimized dose limits for workers, a study of radiation protection optimization was undertaken in gammagraphy facilities, using the Multi-Attribute Utility Analysis technique. A total of 34 protection options, distributed in 6 irradiation scenarios in open fixed type installation, were analyzed. In the determining of the optimized dose limit, the following attributes were considers: cost of the protection, detrimental costs for different alpha values, costs of the isolation area, individual equivalent doses and collective doses. The variables studied in the evaluation included: effective workload, type and activity of the radiation sources, source-operator distance, type and thickness of materials used in the protection shielding. Other parameters analyzed included the quality of the radiographic image and technical procedures employed. The optimal analytic solutions that resulted in the optimized dose limit were determined by means of a sensitivity analysis and by direct and logical evaluations. Thus, independent of the values of the monetary coefficient attributed to the detriment, of the annual interests applied to the protection cost, and of the type of installation studied, it was concluded that the primary limit of the annual dose for workers, 50 mSv, can be easily reduced to an optimized annual dose limit of 5 mSv. (author)