Cyclotron production of [sup 61]Cu using natural Zn & enriched [sup 64]Zn targets

Abstract

Abstract. Copper-61 ( 61 Cu) shares with 64 Cu certain advantages for PET diagnostic imaging, but has a shorter half-life (3.4hr vs. 12.7hr) and a greater probability of positron production per disintegration (61% vs. 17.9%). One important application is for in vivo imaging of hypoxic tissue. In this study 61 Cu was produced using the 64 Zn(p,D) 61 Cu reaction on natural Zn or enriched 64 Zn targets. The enriched 64 Zn (99.82%) was electroplated onto high purity gold or silver foils or onto thin Al discs. A typical target bombardment used 30PA; at 11.7, 14.5 or 17.6MeV over 30-60min. The 61 Cu (radiochemical purity of >95%) was separated using a combination of cation and anion exchange columns. The 64 Zn target material was recovered after each run, for re-use. In a direct comparison with enriched 64 Zn-target results, 61 Cu production using the cheaper nat Zn target proved to be an effective alternative.

Expanding the PET radioisotope universe utilizing solid targets on small medical cyclotrons

“…10 Although less frequently utilized, 60 Cu and 61 Cu have been used to label various bioactive molecules for hypoxia and blood ow studies. 17,21,65 The most commonly used copper radioisotope is 64 Cu, with the rst-in-human use as [ 64 Cu]ASTM for tumor hypoxia. 66 There are several characteristics that make 64 Cu well suited for PET imaging.…”

“…The reaction has been investigated with natural zinc (isotopic composition: 49.17% 64 Zn, 27.73% 66 Zn, 4.04% 67 Zn, 18.45% 68 Zn, 0.61% 70 Zn) foils and enriched 64 Zn electroplated on to gold, silver or aluminum substrates with beam energies ranging from 17.6 to 11.7 MeV (maximum production occurs circa 14.5 MeV). 17 When >99% enriched 64 Zn was bombarded with 14.5 MeV protons, the yield of 61 Cu was 13 MBq (mA h) À1 (i.e. 0.4 mCi (mA h) À1 ) with a purity exceeding 95%.…”

“…0.4 mCi (mA h) À1 ) with a purity exceeding 95%. 17 Despite having completed similar experiments using natural zinc foil targets in the same study, the results were too variable to draw valid conclusions. The primary impurities produced during the bombardment of zinc targets were 66 Ga (t 1/ 2 : 9.5 h, 57.0% b + , 43.0% EC), 67 Ga (t 1/2 : 3.3 d, 100.0% EC) and 68 Ga (t 1/2 : 67.7 min, 88.9% b + , 11.1% EC).…”

“…The primary impurities produced during the bombardment of zinc targets were 66 Ga (t 1/ 2 : 9.5 h, 57.0% b + , 43.0% EC), 67 Ga (t 1/2 : 3.3 d, 100.0% EC) and 68 Ga (t 1/2 : 67.7 min, 88.9% b + , 11.1% EC). 17 Based on the data generated, 61 Cu production from the bombardment of nickel was found to be more efficient than production using zinc. However, the former production route can be expensive due to the high cost associated with enriched 61 Ni.…”

Production of 61Cu by the natZn(p,α) reaction: improved separation and specific activity determination by titration with three chelators

“…To ensure that no contaminating 65 Zn was produced we reduced the incident proton energy to 11.7 MeV [25]. Gamma spectroscopy at EOB of the digested foil prior to separation showed no evidence of 65 Zn.…”