Cherenkov counting of yttrium-90 in the dry state; correlations with phosphorus-32 Cherenkov counting data.

We present data that illustrate some advantages of Cherenkov counting for the radioassay of 90Y in the dry state and provide recommendations concerning sample counting geometry. Slightly higher detection efficiencies and figures-of-merit were obtained when counting 90Y in the dry state in polyethylene plastic counting vials compared to the counting of 90Y in 20 ml of water in borosilicate glass vials. The effects of polyethylene plastic counting vials and sample counting geometry are compared to similar data obtained in the Cherenkov counting of 32P. Data are presented to interpret the effects of polyethylene plastic and borosilicate glass on Cherenkov counting efficiency and background counts. Applications of the Cherenkov counting of 90Y and 32P in the dry state in the biological and radiopharmaceutical sciences are foreseen as well as applications in the analysis of 90Sr(90Y) and 32P in health physics and environmental monitoring.