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The production of ultra high activity 11C-labeled hydrogen cyanide, carbon dioxide, carbon monoxide and methane via the reaction (XV)

1975; Pergamon Press; Volume: 26; Issue: 8 Linguagem: Inglês

10.1016/0020-708x(75)90057-5

1878-1284

David R. Christman, Ronald D. Finn, K.I. Karlstrom, Alfred P. Wolf,

Radiopharmaceutical Chemistry and Applications

Abstract The use of N2O2 or N2H2 pressurized gaseous systems as targets in proton bombardment makes use of the 14 N(p,α) 11 C reaction and allows the facile, quantitative production of H11CN, 11CO2, 11CO or 11CH4 as needed. A system is described for the production of “carrier-free”, high activity (up to 2 Ci) H11CN in an on-line process in the effluent gas stream from a cyclotron target. The target gas is a mixture of 94·5% nitrogen, 5·5% hdrogen, run at a total pressure of 11 atmospheres. The primary products are converted to 11CH4 in over 95 per cent yield by radiolysis in the target, and this, along with NH3 which is concurrently produced radiolytically, is converted quantitatively to “carrier-free” H11CN over platinum wire held at 1000°C. The radiation processes and dosimetry studies involved in the system are discussed. The product is available for use as gaseous H11CN, or in base or carrier sodium cyanide, within 10–12 min after the end of an irradiation. It has been used as such in animal studies and also in the production of carrier-free dopamine-11C and norepinephrine-11C at levels up to 30 mCi at the time of delivery for medical use. An identical target, using tank N2 with trace O2 impurity as the target gas, can be used to produce “carrier-free” 11CO2 at similar activity levels, and from this 11CO or 11CH4 can be made either on-line or by a rapid catalytic reduction.