Tips and tricks gained from years of experience with GE Tracerlab FXC Pro

1038 Objectives: The GE Tracerlab FXC Pro is a commonly used synthesis unit for the synthesis of C-11 PET radiopharmaceuticals. It has integrated C-11 methyl iodide and C-11 methyl triflate synthesis along with the ability to label, purify and formulate the PET radiopharmaceutical using either reactor or loop labeling methods. Below we describe our experience gained over the past 8 years with the GE Tracerlab FXC Pro in optimizing the system for routine C-11 PET radiopharmaceutical synthesis in a cGMP environment. Methods: We have been operating two GE Tracerlab FXC Pros with a GE PETtrace 880 cyclotron with standard GE C-11 cyclotron target since 2010 routinely in a cGMP environment for an average of three C-11 synthesis per day. We routinely synthesize C-11 PiB, C-11 Raclopride, C-11 MeNER (C-11 methylreboxetine), C-11 Altropane and C-11 Methionine for clinical research studies. To optimize the FXC Pro to allow routine labeling with either C-11 methyl iodide or C-11 methyl triflate as well as between either the HPLC loop or reactor, we have modified the FXC plumbing as detailed in Figure 1 to allow the different labeling without replumbing the unit between synthesis. Through our years of experience, we have determined optimal replacement cycles for the valves, tubing and consumables and they are highlighted in Figure 1. Results: The HPLC loop on the FXC Pro was enlarged from 1 to 3mL by adding a 2mL loop connected with unions, which allows the insertion of an injection port at the union for loading precursor onto the HPLC loop. The product collect vial lamp was removed and re-purposed to control two additional valves (L1 \u0026 L2) to allow flow through or bypass of the silver triflate column. We found that successfully maintaining reproducible low level carrier mass was gained through routine use of the FXCs, as well as conditioning of the cyclotron target and FXC prior to use. CO2 traps (NaOH) were previously used on the grade 6 gas for the cyclotron target (1% oxygen in nitrogen), helium and hydrogen gas supply line, but found to slightly suppress the specific activity of the PET radiopharmaceuticals. Impact of gas tank changeover on specific activity was minimized using automated gas tank changeover panels equipped with one-way and purge valves to prevent intrusion of CO2 into the gas supply. The average specific activities of our routinely produced C-11 PET radiopharmaceuticals are detailed in Table 1. We found that the molecular sieves/shimalite nickel in the methane oven as well as the Carboxen in the methane trap began to lose effectiveness after about 18 months of use, therefore, we placed them on a 1-year replacement cycle. We found that the Porapak Q column, as long as protected from iodine, and the silver triflate column, protected from reaction/cleaning solvents, would last several years without any noticeable drops of effectiveness. Conclusions: Through some simple modifications and a routine maintenance plan, the FXCs and the newer generation FX2Cs can be stable and reproducible for routine cGMP production of PET radiopharmaceuticals.