V-48 RADIONUCLIDIC IMPURITY IN PRODUCT STREAMS FROM LIQUID CYCLOTRON TARGETS WITH TITANIUM WINDOWS

Vanadium-48, a positron emitter with a 16.0 day half-life, was observe d in the aqueous product stream from a liquid cyclotron target equippe d with a titanium window, a type of target system commonly used for pr eparing [N-13]NH3 at PET centers. The amount of V-48 activity is direc tly related to bombardment time and beam current. It is apparently pre sent as vanadate ion, and it is efficiently removed by anion exchange cartridges. More generally, it is likely that the specie would be pres ent in the product stream of any titanium-window-equipped liquid targe t which contains water and which is bombarded with protons or deuteron s. Incidental to the V-48 investigation, was quantitation of F-18 in t he system under study.