Development of a Niobium target for routine production of [18F]fluoride with a MC 16 Scanditronix cyclotron

Abstract: The purpose with this work has been to develop and construct a Niobium target for the production of [18F]fluoride with a MC 16 Scanditronix cyclotron. The future demand larger amounts of [18F]fluoride and to satisfy the forthcoming needs an enhanced target needs to be installed on the cyclotron. The old target could have provided the forthcoming needs but to obtain good margins it is important with a better target that benefits the full potential of a MC 16 Scanditronix cyclotron. The old target could only stand approximately half the proton beam capacity of the cyclotron.The work was carried out at the department of Medical Radiation Physics, Jubileum Institute and at the University hospital of Lund. Possible enhancements with the old target were identified and incorporated into the new target. Target parts were constructed in the hospital’s own workshop meanwhile more advanced gadgets had to be ordered from specialized firms. The material of the target chamber was carefully chosen (Niobium) according to chemical inertness, mechanical strength and activation (radioactive isotopes generated when irradiated). Mathematical calculations were applied onto real situations to estimate pressure tolerances and heat transportations. Different foil materials were investigated. Irradiation experiments, of protons into the enriched H218O-water, were performed with a MC 16 Scanditronix cyclotron.The results are very good. For one hour irradiation at 40 μA, 93 GBq F- was produced (extrapolated values) meanwhile for a two hour irradiation at 40 μA, 142 GBq F- was produced (95 % 18O-water). The following synthesis resulted in 87 GBq which correspond to a yield of 62 %. The yield for the FDG synthesis is normal and the productions are large. No discoloration of water occurred. The chemical inertness of the Niobium material has been verified.The new target has increased the production capacity of approximately 300 %, from 32 GBq for the old target, to 93 GBq for the new target (1 hour irradiation). The saturation value per micro amperes is approximately 7.30 GBq/μA. The biggest improvement originates from the new target’s capacity to benefit the full proton beam intensity capacity of the MC 16 Scanditroni