title: Very high specific activity ⁶⁶/⁶⁸Ga from zinc targets for PET.
abstract: This work describes the production of very high specific activity (66/68)Ga from (nat)Zn(p,n) and (66)Zn(p,n) using proton irradiations between 7 and 16 MeV, with emphasis on (66)Ga for use with common bifunctional chelates. Principal radiometallic impurities are (65)Zn from (p,x) and (67)Ga from (p,n). Separation of radiogallium from target material is accomplished with cation exchange chromatography in hydrochloric acid solution. Efficient recycling of Zn target material is possible using electrodeposition of Zn from its chloride form, but these measures are not necessary to achieve high specific activity or near-quantitative radiolabeling yields from natural targets. Inductively coupled plasma mass spectroscopy (ICP-MS) measures less than 2 ppb non-radioactive gallium in the final product, and the reactivity of (66)Ga with common bifunctional chelates, decay corrected to the end of irradiation, is 740 GBq/μmol (20 Ci/μmol) using natural zinc as a target material. Recycling enriched (66)Zn targets increased the reactivity of (66)Ga with common bifunctional chelates.
authors.affiliation: Department of Medical Physics, University of Wisconsin, B1303 WIMR Cyclotron Labs, 1111 Highland Avenue, Madison, WI 53705, USA. engle.jonathan@gmail.com
authors.forename: J W
authors.initials: JW
authors.lastname: Engle
authors.forename: V
authors.initials: V
authors.lastname: Lopez-Rodriguez
authors.forename: R E
authors.initials: RE
authors.lastname: Gaspar-Carcamo
authors.forename: H F
authors.initials: HF
authors.lastname: Valdovinos
authors.forename: M
authors.initials: M
authors.lastname: Valle-Gonzalez
authors.forename: F
authors.initials: F
authors.lastname: Trejo-Ballado
authors.forename: G W
authors.initials: GW
authors.lastname: Severin
authors.forename: T E
authors.initials: TE
authors.lastname: Barnhart
authors.forename: R J
authors.initials: RJ
authors.lastname: Nickles
authors.forename: M A
authors.initials: MA
authors.lastname: Avila-Rodriguez
mesh_terms: D005710:Gallium Radioisotopes / Q000737:chemistry / Q000494:pharmacology*; D049268:Positron-Emission Tomography; D015032:Zinc / Q000737:chemistry*
chemical_list: D005710:Gallium Radioisotopes; D015032:Zinc