Proton-induced production and radiochemical isolation of 44 Ti from scandium metal targets for 44 Ti/ 44 Sc generator development.

Scandium-44g (half-life 3.97h) shows promise for application in positron emission tomography (PET), due to favorable decay parameters. One of the sources of ^44g Sc is the ⁴⁴ Ti/ ^44g Sc generator, which can conveniently provide this radioisotope on a daily basis at a diagnostic facility. Titanium-44 (half-life 60.0 a), in turn, can be obtained via proton irradiation of scandium metal targets. A substantial ⁴⁴ Ti product batch, however, requires high beam currents, long irradiation times and an elaborate chemical procedure for ⁴⁴ Ti isolation and purification. This study describes the production of a combined 175MBq (4.7mCi) batch yield of ⁴⁴ Ti in week long proton irradiations at the Los Alamos Isotope Production Facility (LANL-IPF) and the Brookhaven Linac Isotope Producer (BNL-BLIP). A two-step ion exchange chromatography based chemical separation method is introduced: first, a coarse separation of ⁴⁴ Ti via anion exchange sorption in concentrated HCl results in a ⁴⁴ Tc/Sc separation factor of 10 ² -10 ³ . A second, cation exchange based step in HCl media is then applied for ⁴⁴ Ti fine purification from residual Sc mass. In summary, this method yields a 90-97% ⁴⁴ Ti recovery with an overall Ti/Sc separation factor of ≥10 ⁶ .
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