Very high specific activity 66/68Ga from zinc targets for PET

Abstract

This work describes the production of very high specific activity 66/68Ga from natZn(p,n) and 66Zn(p,n) using proton irradiations between 7 and 16 MeV, with emphasis on 66Ga for use with common bifunctional chelates. Principle radiometallic impurities are 65Zn from (p,x) and 67Ga 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-quantitiative 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 66Ga 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 66Zn targets increased the reactivity of 66Ga with common bifunctional chelates.

Production of Y-86 and other radiometals for research purposes using a solution target system

“…The method used by us [23] retained in the first step copper and zinc on the sorbent, which required a high amount of sorbent (7 g), long separation times (> 1h) and an high elution volume (20 mL 4M HCl). A second step was therefore necessary to concentrate the eluate (final volume 1 mL).…”

“…For the separation of 68 Ga from the Zn target solution we adapted a method from Engle et al [23]. The …”

“…The desired radiometals were separated from the irradiated solutions using procedures adapted from previously published methods [9,19,23,25,29], see Table 6 for results. The efficiency of the separations ranged from 82 ± 5 ( 89 Zr) to 99 ± 4 % ( 86 Y).…”

In vivo targeting and positron emission tomography imaging of tumor vasculature with 66Ga-labeled nano-graphene

“…The reactivities of 66 Ga for common bifunctional chelators exceeded 70 GBq/μmol [14], which were significantly higher than the previously reported values (< 4.6 GBq/μmol) [15]. The relatively long half-life of 66 Ga makes it a suitable radiolabel for nanomaterials such as GO, whose in vivo kinetics is poorly matched by the much shorter half-life of 68 Ga (t 1/2 = 68.3 min).…”

Design and development of a semi-automated module for the preparation of metallic PET radionuclides

“…The longer half-life of Gallium-66 makes it a practical radiolabel of proteins, peptides, and antibody fragmanets. 4 On the other hand, the 78.4 h half-life of Zirconium-89 is ideal for labeling intact monoclonal antibodies. 5 Future clinical applications of these tracers will require them to be produced reliably and efficiently without increasing radiation exposure to personnel.…”