A quartz-lined carbon-11 target: striving for increased yield and specific activity

Introduction: The increased demand for high specific radioactivity neuroreceptor ligands for positron emission tomography (PET) requires the production of high specific radioactivity carbon-11 in high yields. We have attempted to address this issue with the development of a new quartz-lined aluminium target for the production of [(11)C]methane or [(11)C]carbon dioxide.

Methods: The new target has been tested with respect to yields of [(11)C]methane and [(11)C]carbon dioxide, and the effect of the quartz liner has been evaluated. The specific radioactivities of a large number of radiopharmaceuticals produced using this target have also been measured.

Results: The described target produces [(11)C]-labelled gases in excellent yields, and losses of radioactivity in the target on production of [(11)C]methane have been reduced significantly by the use of a quartz liner. Radiopharmaceuticals with specific radioactivities up to 9000 GBq/μmol at end of bombardment (EOB) (243 Ci/μmol) have been produced using this target.

Conclusions: We have developed a reliable, high-yielding carbon-11 gas target which is now routinely used in our department for the production of high specific activity radiopharmaceuticals.