An orally bioavailable aqueous solution containing the chloride salt of the radioisotope calcium-46 (46Ca) with phosphate-binding and radioisotopic activities. Upon administration of calcium-46 chloride aqueous solution, calcium-46 is preferentially taken up by osteoblasts, which generate mineralized osteoid containing calcium. Calcium-46 accumulation and turnover in bone can be measured with bone scintigraphy and urinary isotope excretion testing. Check for active clinical trials using this agent. (NCI Thesaurus)