한국형 사이클로트론(KOTRON-13)을 이용한 [¹¹C]CO₂ 생산과 다양한 ¹¹C-표지 방사성의약품 생산 적용

Production of ¹¹C labeled Radiopharmaceuticals using [¹¹C]CO₂ Produced in the KOTRON-13

Purpose : The KOTRON-13 cyclotron was developed and installed in regional cyclotron centers to produce short-lifetime medical radioisotopes. However, this cyclotron has limited capacity to produce ¹¹C so far. In present study, we developed an effective ¹¹C target system combining with fluorine-18 target and applied to the production of various ¹¹C radiopharmaceuticals. Materials and Methods : To develop the optimal ¹¹C target system and effective its cooling system, we designed the ¹¹C target system by Stopping and Range of Ions in Matter (SRIM) simulation program and considered the cavity pressure during irradiation at target grid. In this investigation, we modified target materials, cavity shapes and the position of cooling system in ¹¹C target and then evaluated [¹¹C]CO₂ production at different beam currents, thickness of the target foil, oxygen content of nitrogen gas and target gas loading pressure. Also, we evaluate the production of several ¹¹C radiopharmaceuticals such as [¹¹C]PIB, [¹¹C]DASB, and [¹¹C]Clozapine. Results : [¹¹C]CO₂ was produced about 74 GBq for 30min irradiation at 60 ㎂ of beam current as following conditions: thickness of the target foil: 19 nm HAVAR, oxygen content of nitrogen: under 50 ppb, target gas loading pressure: 24 bar. Additionally, the cooling system was stable to produce [¹¹C]CO₂ at high beam current. The radiochemical yields of [¹¹C]PIB, [¹¹C]DASB, and [¹¹C]Clozapine showed about 26-38% with over 127 GBq/umol of specific activity. Conclusion : The carbon-11 target system in the KOTRON-13 cyclotron was successfully developed and showed stable production of [¹¹C]CO₂. These results showed that our ¹¹C target system will be compatible with other commercial system for the routine ¹¹C radiopharmaceuticals production in the KOTRON-13 cyclotron.