The secular equilibrium Sr/Y-90 found application in nuclear medicine, because Y-90, decaying to stable Zr-90, emits the high energy betas (2.27 MeV), and therefore the Sr/Y-90 sources are used in intravascular brachytherapy. The high specific activity Sr/Y-90 sources are prepared by encapsulation of Sr-loaded resin into small seeds coated with a thin gold layer. Consider a 0.1 g sample of a Sr-selective resin with a known high distribution ratio (D, KD) for Sr =10,000 mL/g. After a 30-min contact with 10 mL of Sr-90 loading solution, the residual concentration of Sr-90 in the contacted solution measured 1 Bq/mL. Based on the definition of the solid/liquid distribution ratio, estimate the activity concentration of Sr-90 in the resin (=specific activity of brachytherapy resin).

Select one from the options below;

100 kBq/g

10 kBq/g

1 kBq/g

100 Bq/g