PRODUCTION OF NO-CARRIER-ADDED (CU)-C-64 FROM ZINC METAL IRRADIATED UNDER BORON SHIELDING

Background. Positron emission tomography offers advantages for radioim munodiagnosis of cancer but requires radionuclides of appropriate half -life that have high specific activity and high radio-purity. This wor k was designed to develop a viable method to produce and purify Cu-64, which has high specific activity, for positron emission tomography. M ethods. Cu-64 was produced at the University of Missouri Research Reac tor by the nuclear reaction, Zn-64(n,p)Cu-64. Highly pure zinc metal ( 99.9999%) was irradiated in a specially designed boron nitride lined c ontainer, which minimized thermal neutron reactions during irradiation . A new two-step procedure was developed to chemically separate the no -carrier-added Cu-64 from the zinc metal target. Results. Cu-64 recove ry for 24 runs averaged 0.393 (+/-0.007) mCi per milligram of zinc irr adiated. The boron-lined irradiation container reduced unwanted zinc r adionuclides 14.3-fold. Zinc radionuclides and non-radioactive zinc we re separated successfully from the Cu-64. The new separation technique was fast (2 hours total time) and highly efficient for removing the z inc. The zinc separation factor for this technique averaged 8.5 X 10(- 8), indicating less than 0.0000085% of the zinc remained after separat ion. Thus far, the highest Cu-64 specific activity at end of irradiati on was 683 Ci/mg Cu, with an average of 512 Ci/mg Cu for the last six analyzed runs. Conclusion. The boron-lined irradiation container has s ufficient capacity for 75-fold larger-sized zinc targets (up to 45 g). The new separation technique was excellent for separating Cu-64, whic h appears to be a radionuclide with great potential for positron emiss ion tomography.