- Conference date: 26–29 August 2012
- Location: Playa del Carmen, Máxico
The development of biological targeting agents such as proteins, peptides, antibodies and nanoparticles with a range of biological half-lives demands the production of new radionuclides with half-lives (physical) complementary to these biological properties. Zirconium-89 ( ) is a promising radionuclide for development of new immuno-PET agents due to its convenient half-life of 78.4 h, β+ emission rate of 23%, low maximum energy of 0.9 MeV resulting in good spatial resolution, stable daughter isotope of Yttrium-89 ( ) and favorable imaging characteristics, with only one significant γ-line of 909 keV emitted during decay alongside the 511 keV positron photons. Our aim was to prove that isotopically pure could be produced in an IBA Cyclone 18/9 cyclotron equipped with a COSTIS STS using the reaction and optimise the yield by reducing the beam degrader thickness without producing either or . The degradation of the beam energy with 400 and 500 μm thick Niobium foils were achieved without overheating problems with 2-3 hours long irradiation times. From repeated measurements of activity, it was clear that there is a bi-exponential decay of radioactivity due to the short lived and . The measured half-life of the longer lived radionulide was consistent with value for . The energy spectrum from had energy peaks at 511 keV and 909 keV and was consistent with . Production of with 500 μm thick Niobium beam degrader ( ) was achieved, without producing either or . It was necessary to wait at least 4 hours before measuring the activity and decay correct in order to calculate the activity at the end of cyclotron production. Degrading the proton beam to 10 MeV produces radionuclidically pure with yields from 8 to 9 MBq/μAh. Whilst this is enough for pre-clinical use, the yield is not enough for either clinical use or commercial supply. Using thinner beam degraders to increase the proton beam energy increases the radionuclidic yield but it is not yet possible to exclude the presence of radionuclidic impurities.
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