Consecutive automated production of ¹¹C-labeled radiopharmaceuticals by sharing methyliodide from one ¹¹C-synthetic module

Objectives ¹¹C-abeled radiopharmaceuticals have to be produced immediately following prepare gas-type reagent (¹¹C-CH₃I or ¹¹C-CH₃OTf) from the synthetic module due to the short half-life of carbon-11. Recently, according to increasing ¹¹C-labeled radiopharmaceuticals, there is a need for new methodology giving consecutive production in short time using one ¹¹C-synthetic module without additional purchase. We therefore describe consecutive production of ¹¹C-PIB and -methionine using one ¹¹C-synthetic module by sharing ¹¹C-CH₃I.

Methods To produce ¹¹C-PIB and -methionine, two synthetic modules were used: one is the TRACERlab FX C pro and the other is old and unused ¹⁸F-synthetic modules, and each modules was connected with 3-way valve to sharing ¹¹C-CH₃I prepared from ¹¹C-synthetic module. First, ¹¹C-PIB was produced in the TRACERlab FX C pro module and 2^nd beam irradiation was carried out during purification process of ¹¹C-PIB. ¹¹C-Methionine was synthesized in the ¹⁸F-synthetic module using ¹¹C-CH₃I which was resynthesized in the ¹¹C-synthetic module.

Results The produced radioactivity of ¹¹C-PIB and ¹¹C-methionine were 4.1±0.4 GBq (5.4±0.6%, n.d.c.) and 15.2±1.1 GBq (16.7±0.8%, n.d.c.), respectively, with over 97% of radiochemical purity. The specific activity of ¹¹C-PIB was over 107 GBq/μmol. Total production time of two radiopharmaceuticals needs about 2 h from 1^st beam irradiation including quality control test. Final ¹¹C-PIB and ¹¹C-methionine were satisfied all quality control test standards.

Conclusions We developed a method which can be produced two ¹¹C-radiopharmaceuticals within 2 h in the ¹¹C- and ¹⁸F-synthetic module. Studies for the assessment of long term stability of the new developed production system are still undergoing.