Abstract
1689
Objectives Boron Neutron Capture Therapy (BNCT) is an anticancer treatment with alpha and Li particles produced by 10B(n, α)7Li reaction in tumors. In the BNCT, 10B-phenylalanine (BPA) is administered to deliver 10B to tumors. Before irradiation, it is very important to evaluate the amount of 10B in the tumor cells. For this purpose, PET with 4-Borono-2-[18F]fluoro-L-phenylalanine (FBPA) has been employed. In this study, we optimized the synthesis condition of [18F]FBPA with high specific radioactivity and enough radioactivity for clinical use.
Methods [18F]FBPA is synthesized by direct fluorination of BPA with [18F]CH3COOF converted from [18F]F2. We tested the concentration of carrier F2 gas (0.05 - 1.0%) and recovery gas flow rate of [18F]F2 (150 - 600 ml/min), with the deuteron irradiation at 10µA for 10 or 60 min. Then we synthesized [18F]FBPA under the optimized condition at 20µA for 150 min bombardment.
Results [18F]F2 radioactivity was approximately 300, 500 and 900 MBq with 0.05, 0.1 and 0.2% of carrier F2 gas respectively for 10 min bombardment. . By increasing F2 gas more than 0.2%, [18F]F2 radioactivity was not increased. The conversion rate to [18F]CH3COOF was approximately 35% with any concentration of F2 gas. By increasing F2 gas, specific radioactivity and recovery efficiency of [18F]FBPA became low. In the recovery gas flow rate, [18F]F2 radioactivity and the conversion rate to [18F]CH3COOF with gas flow rate of 150 ml/min were lower than that of 600 ml/min. Specific radioactivity and recovery efficiency of [18F]FBPA were not influenced by gas flow rate. The optimized method synthesized 740 MBq of [18F]FBPA at 20µA for 150 min bombardment.
Conclusions The concentration of carrier F2 gas of 0.2% and recovery gas flow rate of 600ml/min resulted in the highest [18F]FBPA production with high specific radioactivity. It became possible to test five patients per production