Strontium cation Sr-85 is a soft, silver-yellow, alkaline-earth metal, existing either in the elemental state or as the divalent ion. Strontium-85 is a radioactive isotope that has a half-life of 64.84 days and it has been used for photoscanning in 1960s. Strontium 85 is admirably suited for photoscanning since, in its decay by electron capture to stable rubidium 85, a single gamma photon of 0.51 Mev is emitted. The material has administered intravenously, 50 µc to adults and 20 µc to patients under twenty years of age. The estimated total body dose to a standard man is 0.325 rads and the bone dose is 2.28 rads