Analysis of the accumulation of β-emitting radionuclides in the production of radiopharmaceuticals based on 18F using the IBA CYCLONE 18/9 HC cyclotron

Abstract

In order to clarify the scheme of radioactive waste management, the accumulation of undesirable beta-emitting radionuclides (PH) in the production of radiopharmaceuticals based on 18F using the IBA CYCLONE 18/9 HC cyclotron was investigated. It is shown that the dominant impurity PH is tritium, which is formed by the reaction of 18O(p, t) 16O when water is irradiated with [18O]H2O protons. The main proportion of 3H (about 95%) remains in the regenerated water. 1.6 % of the accumulated tritium activity is carried away from the synthesis zone with gases and water vapor. Tritium-containing waste (regenerated water in vials) can be considered as waste of a very low level of activity during disposal. With an increase in the operating time of the target over 2500 µA · h, the processes of corrosion /erosion of target materials increase, which leads to a sharp increase in the concentration of undesirable radionuclides in regenerated water, sorption purification cartridges and the finished dosage form. The concentration of tritium does not increase significantly. In the β-spectra of regenerated water [18O]H2O and the finished radiopharmaceutical [18F]NaF, in addition to the maximum due to tritium, a number of maxima appear in both the low- and high-energy parts of the spectrum. Other undesirable β-emitters accumulate in water as a result of leaching of the activated target wall. The possibility of using measurements of tritium activity in water [18O]H2O as an indicator of its re-enrichment has been demonstrated. The necessity of controlling the content of impurity beta-emitting PH in intermediate products, production waste and final radiopharmaceutical is shown.