[en] The demand growing in Brazil by the radiopharmaceutical [¹⁸F]FDG in positron emission tomography (PET-CT) and the 109,7 minutes half life claim special attention to the productive chain of this radiopharmaceutical. Since the [¹⁸O]water irradiation until the tomograph patient scanning, in sequential procedures that may spent about six hours, all the productive chain stages must be as reliable as possible, because any stage failed will be perceived in productive chain extremity. The position indication absence from Load and Unload ¹⁸F- Target System valve in Cyclotron Accelerators Center resulted in ¹⁸F- production loss, Irradiation Room contamination and the increase workers' dose responsible by operation and maintenance of irradiation systems. This study tested the behaviour of three types of position sensors (micro switch, reed switch and inductive sensor), into Irradiation Room 1.2 environment of the Cyclotron Accelerators Center, where there are high gamma radiation and neutrons rates because the routine ¹⁸F- and ¹'2³I production, through this test was possible to discover the fitter position sensor to run on ¹⁸F- Target, and after rewriting the programmable logic controller software was possible avoid this type of fail at ¹⁸F- production time in Cyclotron Accelerators Center, and to grow up the reliability on [¹⁸F]FDG productive chain. (author)