An automated radiosynthesis of 2-[11C]thymidine using anhydrous [11C]urea derived from [11C]phosgene. |
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| Authors: | C J Steel F Brady S K Luthra G Brown I Khan K G Poole A Sergis T Jones P M Price |
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| Institution: | MRC Cyclotron Unit, Imperial College School of Medicine, Hammersmith Hospital, London, UK. |
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| Abstract: | 2-11C]Thymidine has been produced from 11C]methane via 11C]phosgene and 11C]urea. Anhydrous 11C]urea was prepared from 11C]phosgene by reaction with liquid ammonia. This novel approach avoids the problems associated with the synthesis of anhydrous 11C]urea from 11C]cyanide. A fully automated system based on a modular approach and under PLC control has been developed. The system provides 2-11C]thymidine reliably and reproducibly for clinical PET studies. The radiosynthesis takes 45-50 min from 11C]methane and the average yield was 1.5-3.3 GBq (40-90 mCi). The specific radioactivity was typically in the range 29.6-51.8 GBq mumol-1 (0.8-1.4 Ci mumol-1) at EOS corresponding to 6-12 micrograms of stable thymidine. The radiochemical yield of 2-11C]thymidine was ca. 14% from 11C]methane. |
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