Radiation monitoring in a medical cyclotron facility during the production of 18F labelled FDOPA

Full text: The Medical Cyclotron Facility at INMAS GE PETtrace is an integrated PET tracer production system, which includes a negative-ion cyclotron, a standard chemistry system and a control system. The system is used for the routine production and synthesis of 18F labelled radiotracers (e.g. fluoride, FDG) and other research PET radiotracers (e.g. FDOPA, FLT, FMISO, 11C-labeled methionine). The medical cyclotron is an unshielded type that is housed in a concrete bunker. The total extracted beam current on the target is at least 80 μA for protons and at least 60 μA for deuterons. The synthesis of 18F-labeled 6-(18F)fluoro-L-DOPA starting from (18F )F2 is based on an electrophilic fluorination reaction. The (18F) fluorine is produced via the 20Ne (d, α) 18F nuclear reaction on target number six of the system. The (18F) labelled Fluoro-DOPA is produced from this (18F)F2 activity in a compact automated radiochemistry system GE TRACERlab FXFDOPA. The radiation levels in the medical cyclotron and radiochemistry facility were measured using Rotem's MediSmarts comprehensive radiation monitoring system. The system provides on line production monitoring, stack monitoring and area monitoring. During production and synthesis of 18F labelled FDOPA, the radiation levels were measured in the cyclotron vault, radiochemistry room, beam extension, stack and the control console. Before irradiation, the gamma radiation level in the cyclotron vault ranged from 60 μSv/h to 200 μSv/h at 1 m from the cyclotron. During irradiation, the gamma radiation level inside the cyclotron vault was more than 100 mSv/h at 1 m from the detector and the neutron radiation level ranged from 84 mSv/h to 131 mSv/h. The radiation levels in the radiation chemistry laboratory were on the order of 0.1 to 0.4 μSv/h during the synthesis. The gamma radiation level inside the beam extension ranged from 1 - 6 μSv/h and neutron radiation level ranged from 9 μSv/h to 18.2 mR/h. The gamma radiation levels on the console were measured to be in the range 0.1 - 0.4 μSv/h when the beam was ON and the levels did not exceed 0.1 μSv/h when the beam was OFF. There was no neutron radiation level on the control console