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  • Author or Editor: R. Weinreich x
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Abstract  

For more than a year,124I (T=4.15 d) has been produced routinely with a compact cyclotron by irradiation of124TeO2 with 14 MeV deuterons, followed by dry distillation of the iodine radioisotopes formed from irradiated target materials. The following by-products have been measured and compiled in each charge: 13.2-d123I, 60-d125I, 13.0-d126I, 12.4-h130I and 8.02-d131I. The data show that after 45 h decay time, the sum of the activities of these nuclides is less than 5% of the124I activity. Observation of this limit has been required by the Swiss Regulatory Agencies for a PET study of cell proliferation in human brain tumors using [124I] IUdR.

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Abstract  

A fast and easy method for the preparation of radiolabeled 5-halo-2-deoxyuridine (halo=[76Br], [123I] and [211At]) is presented. Labeling is accomplished by oxidation of the halogenide with Iodogen for [123I] and [211At], and Chloramine-T (CAT) for [76Br] followed by halodestannylation of 5-trimethylstannyl-2-deoxyuridine (TMSUdR). The reaction takes 1 minute giving >90% yield for all three halogens.

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Abstract  

A target system for the production of nucleophilic 110-min18F from isotopically enriched /18O/H2O is described. The process occurs via the nuclear reaction18O/p,n/18F, the available proton beam of 72 MeV must be degraded to the entrance energy of 15 MeV. This process is in regular use for the batch production of 0.8–1 Ci18F.

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Abstract  

The advantages of high energy cyclotrons as compared to small compact cyclotrons for the production of special radionuclides are outlined. The routine production of123I (T=13.3 h) and28Mg (T=21.1 h) by means of high energy nuclear reactions at the Jülich Isochronous Cyclotron is described. The reaction127I(d,6n)123

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123I at 78 to 64 MeV is used for the production of123I with thick target yields of 8 mCi/μAh and high radionuclidic purity. The practical experience in the application of this process, which is well suited for the production of Na123I and for123Xe-exposure labelling techniques, is reported.28Mg is produced by the27Al(α, 3p)28Mg reaction at Eα=140 to 30 MeV with thick target yields of 40 μCi/μAh. The carrier-free28Mg is separated from the matrix activities by coprecipitation and anion exchange with chemical yields of 80%.

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Abstract  

The formation of plutonium radionuclides (239+240Pu) from uranium was determined in dismounted shielding concrete from accelerator components. Plutonium and uranium fractions were separated by radioanalytical techniques and measured by -spectroscopy. The measurements are consistent with yield calculations based on transport and single particle codes. The yield of 239+240Pu did not exceed the two-fold exemption limit given in the Swiss Radiation Protection Law, thus the plutonium content in shielding concrete should not cause problem for the environment.

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