Production, processing and small animal PET imaging of titanium-45

Abstract

Introduction Titanium-45 was prepared as a tool for elucidation of the mechanism of action of titanium anticancer drugs in vivo using microPET imaging. Methods Titanium-45 was produced by the 45Sc(p,n) 45Ti nuclear reaction using 14.5 MeV protons. Sufficient yields of 45Ti were produced and separated from the target material with 99.8% radionuclidic purity using a simple, efficient separation procedure. Results A typical bombardment of 5 μA for 1 h produced an average of 2105±150 MBq (56.9±4.0 mCi) at the end of bombardment (EOB), well within acceptable range of the calculated theoretical yields of 2165 MBq and 433 MBq μA –1 h –1 (58.5 mCi and 11.7 mCi μA –1 h –1). This amount of activity is sufficient for the radiosynthesis of target compounds as well as imaging studies. MicroPET images of a miniature Derenzo phantom show excellent resolution where rods of 1.25 mm were separated by four times their diameter. Conclusions Titanium-45 can be easily produced on a biomedical cyclotron with excellent yields as compared to calculated theoretical values with imaging studies demonstrating that the decay properties of titanium-45 are well suited for microPET.