Influence of electroplating uniformity of enriched 68 Zn targets on radiochemical distribution in cyclotron-based 68 Ga production

Abstract

Abstract Cyclotron-based production of gallium-68 ( 68 Ga) using enriched zinc-68 ( 68 Zn) targets is increasingly adopted as an alternative to generator-based systems. In this approach, electroplating of enriched 68 Zn onto target substrates is a critical upstream process; however, the relationship between plating morphology and downstream radiochemical behavior remains insufficiently characterized. This operational study investigated the association between electroplating uniformity and radiochemical distribution during cyclotron-based 68 Ga-PSMA-11 production. Enriched 68 Zn targets were prepared by electroplating on Au backing plates and classified as uniform or non-uniform based on photographic and operational morphology. Production performance was reviewed across 20 runs, and representative component-level activity distributions were evaluated across product, purification media, and waste fractions with decay correction. Across 20 runs, TBP-associated 68 Ga activity was 3.56 ± 1.06 GBq, and final 68 Ga-PSMA-11 product activity was 2.07 ± 0.81 GBq. Seventeen runs achieved routine output, whereas three runs showed low output relative to the intended future two-patient production target, although single-patient administration remained feasible. Low-output runs showed a lower product-to-TBP activity ratio than routine-output runs (0.371 ± 0.221 vs. 0.616 ± 0.074). Representative component-level distributions showed increased retention in C18, TK200, and waste fractions under abnormal conditions and progressive normalization after process improvement. These observations suggest that electroplating morphology is associated with downstream radiochemical distribution and product recovery. Because direct thickness mapping, spatial beam-profile measurement, and direct Ga speciation analysis were not performed, the proposed mechanism should be regarded as a working hypothesis rather than definitive proof of causality.