Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 50 (2017)

Specification of 67Cu produced in the 70Zn(d,Dn)67Cu reaction
S. Yano,䠆1 H. Haba,䠆1 S. Shibata,䠆1 Y. Komori,䠆1 K. Takahashi,䠆1 Y. Wakitani,䠆2 T. Yamada,䠆2 and M. Matsumoto䠆2Copper-67 (half life T1/2   K DQG ȕ±-decay branchIȕ- = 100%) is one of the promising radioisotopes forradiotherapy and radiodiagnosis.1) In our preliminary
study,2) about 70 kBq of 67Cu was produced in the70Zn(d,Įn)67Cu reaction at the AVF cyclotron. Theproduction yield of 67Cu was 4.0 MBq/ȝ$ h at 24-MeV
deuteron beam energy. We also investigated a chemical
purification procedure for 67Cu. The chemical yield of 67Cu
was 97%, and the decontamination factors for Ga and Zn
were evaluated to be ~103 and >103, respectively. In thiswork, we developed a new irradiation chamber to produce alarger amount of 67Cu (> 100 MBq) with a more intense
deuteron beam. About 100 MBq of the purified 67Cu wasobtained and its radionuclidic purity, specific radioactivity,and chemical purity were evaluated.
A schematic of the 67Cu production chamber is shown inFig. 1. The 24-MeV deuteron beam with an intensity of 4
PA was extracted from the AVF cyclotron. The70
Zn-enriched oxide (70ZnO) powder was prepared as a disk
with 10-mm diameter and 340-mg cm-2 thickness at apressure of 2×103 kg cm-2 for 3 min. The isotopic
composition of the 70Zn target was 96.87% 70Zn, 1.55%
68Zn, 0.09% 67Zn, 0.55% 66Zn, and 0.94% 64Zn. As shownin Fig. 1, the 70ZnO disk placed on a Ta beam stopper wascovered by a high-purity Al foil 10 Pm in thickness. During
the irradiation, the 70ZnO target was cooled with circulating
helium gas (30 L min±1) and water (1.5 L min±1).The beamaxis was continuously rotated in 3-mm diameter at 2 Hz toavoid local heating of the target using electromagnets on thebeam line of the AVF cyclotron.After the 10-h irradiation,
67
Cu was separated from the target material and by-products
such as 67Ga, 69mZn, and 71Zn through the chemical
procedure reported in Ref.2) The purified 67Cu was obtained
as 300 PL of 0.1 M CH3COOH for synthesis of the67
Cu-labeled antibody.3) The radioactivity and radionuclidic
purity was determined by Ȗ-ray spectrometry using a Gedetector. The specific radioactivity and chemical purity
were also evaluated by chemical analysis using aninductively coupled plasma mass spectrometer (AgilentTechnologies 7700x).
A Ȗ-ray spectrum of the purified 67Cu is shown in Fig. 2.
135 MBq of 67Cu was produced at the end of bombardment(EOB).The major radionuclidic impurity in the purified67
Cu was 64Cu (T1/2 = 12.70 h). The radioactivity ratioA(64Cu)/A(67Cu) was 1.2×10±2 at EOB, which decreased to
8.9×10±4 at 60 h after EOB (a typical time for its applicationstudies). The present A(64Cu)/A(67Cu) ratio is smaller than
the typical value of 6.7 in the 68Zn(p,2p)67Cu reaction.4) The
radionuclidic purity of the 67Cu solution was then evaluated䠆1䠆2to be >99.9% 60 h after EOB. In the ICP-MS analysis, onlyCu (2.1 ppm) and Br (1.0 ppm) were detected withconcentrations >1 ppm among the elements having atomicnumber Z  20. The specific radioactivity of 67Cu was thendetermined to be 0%TȝJ-1 at EOB. Hundreds of MBqof the purified 67Cu are ready for application studies. The
results of synthesis of the 67Cu-labeled antibody will bereported elsewhere.3)
Circulating helium gas
30 L/min
50 mm

Circulating water
1.5 L/min
HeBeam wobbler

Water
70ZnO target

Al foil
Be vacuum window
Ta beam stopper

Fig. 1. Schematic of the new 67Cu production chamber.
108Counts / 0.5 keV

107
106
10: 67Cu5104103
102
101
100

0500

1000
Energy / keV

1500

2000

Fig. 2. Typical J-ray spectrum of the purified 67Cu.
References
1) I. Novak-Hofer et al., Eur. J. Nucl. Med. 29, 821 (2002).
2) S. Yano et al., RIKEN Accel. Prog. Rep. 49, 22 (2016).
3) K. Fujiki et al., private communication.
4) In Cyclotron Produced Radionuclides: Physical Characteristics
and Production Methods, IAEA Technical Reports Series 468,
100 (2009).

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