Photonuclear target systems for producing clinically useful quantities of 1 1 C using an electron linear accelerator

Described in this paper are what we believe to be the first practical photonuclear target systems for production of 1 1 C containing CO and CO 2 using bremsstrahlung produced from an electron linear accelerator similar to certain radiotherapy accelerators. This is a continuation of work reported earlier concerning a similar target system presently being used for production of 1 5 O–O 2 . The 1 1 C producing systems utilized liquid carbon dioxide, liquid cyclohexane, and liquid glacial acetic acid target materials. The carbon dioxide and glacial acetic acid target materials produced principally a 1 1 C–CO product material. The cyclohexane target material produced a 1 1 C–hydrocarbon product which was then oxidized to CO 2 . Target activity yields for these systems, normalized to a 20‐cm‐long by 10‐cm‐diam target chamber irradiated in a bremsstrahlung field produced by a 26‐MeV, 100‐μA electron beam, were 1.9×10 8 Bq (5 mCi) at 7.4×10 8 Bq g − 1 (20 mCi g − 1 ) for carbon dioxide, 1.4×10 8 Bq (3.8 mCi) at 3.7×10 1 0 Bq g − 1 (1 Ci g − 1 ) for cyclohexane, and 7.4×10 8 Bq (20 mCi) at 3.7×10 1 0 Bq g − 1 (1 Ci g − 1 ) for glacial acetic acid.