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

Valery Radchenko; Jonathan W Engle; Dmitri G Medvedev; Joel M Maassen; Cleo M Naranjo; George A Unc; Catherine A L Meyer; Tara Mastren; Mark Brugh; Leonard Mausner; Cathy S Cutler; Eva R Birnbaum; Kevin D John; F Meiring Nortier; Michael E Fassbender

doi:10.1016/j.nucmedbio.2017.03.006

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

Nucl Med Biol. 2017 Jul:50:25-32. doi: 10.1016/j.nucmedbio.2017.03.006. Epub 2017 Apr 7.

Authors

Affiliations

¹ Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA.
² Collider-Accelerator Department, Brookhaven National Laboratory, Bldg 801, Upton, NY 11973, USA.
³ Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA. Electronic address: mifa@lanl.gov.

PMID: 28432915
DOI: 10.1016/j.nucmedbio.2017.03.006

Abstract

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 ^44gSc is the ⁴⁴Ti/^44gSc 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 ⁴⁴Ti product batch, however, requires high beam currents, long irradiation times and an elaborate chemical procedure for ⁴⁴Ti isolation and purification. This study describes the production of a combined 175MBq (4.7mCi) batch yield of ⁴⁴Ti 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 ⁴⁴Ti via anion exchange sorption in concentrated HCl results in a ⁴⁴Tc/Sc separation factor of 10²-10³. A second, cation exchange based step in HCl media is then applied for ⁴⁴Ti fine purification from residual Sc mass. In summary, this method yields a 90-97% ⁴⁴Ti recovery with an overall Ti/Sc separation factor of ≥10⁶.

Keywords: (44)Ti; (44)Ti/(44g)Sc generator; Ion exchange chromatography; Proton irradiation; Scandium target.

MeSH terms

Gamma Rays
Protons*
Radiochemistry / instrumentation
Radiochemistry / methods*
Radioisotopes / chemistry*
Radioisotopes / isolation & purification*
Scandium / chemistry*
Titanium / chemistry*
Titanium / isolation & purification*

Substances

Protons
Radioisotopes
Scandium-44
Titanium-44
Titanium
Scandium