TDCR Cherenkov counting for determining 90Y activity in blood samples.

Yttrium-90 (90Y) microsphere radioembolization is a promising internal therapy for treatment of hepatic tumors. Development of a precise method for measuring the activity of 90Y in blood samples is needed to facilitate preclinical safety assessment of drugs. This paper presents the development of a triple-to-double coincidence ratio (TDCR) Cherenkov counting method for quantifying blood 90Y activity. The impact of heating temperature and the quantities of nitric acid and H2O2 on wet oxidation of blood were studied for rapid sample preparation. Elevated heating temperatures and the addition of concentrated nitric acid expedited blood decolorization and effectively suppressed chemiluminescence interference. The addition of H2O2 also accelerated blood decomposition while mitigating sample color quenching. The digested samples were counted using a Hidex 300SL liquid scintillation counter for 5 minutes, and a minimum detectable activity of 0.31 kBq/L was achieved with the region of interest (ROI) analysis window set at 80–300 channels. The method was validated using whole blood samples spiked with varying activities of 90Y in the range of 3.37–51.15 kBq/L. [ABSTRACT FROM AUTHOR]