Chemistry for commercial scale production of yttrium-90 for medical research

Studies were initiated at Oak Ridge National Laboratory (ORNL) in 1982 for the radiolabeling of resin microspheres with yttrium-90 (90Y) for liver cancer therapy. Yttrium-90 is the decay product of strontium-90 (90Sr). Subsequently, 90Y became a major radioisotope of choice for labeling antibodies for therapeutic trials in the treatment of other forms of cancer. A 25-Ci 90Y 90Y generator or 90Sr cow was placed in service to supply the anticipated needs of customers. In vivo use of 90Y required that the 90Sr contamination levels be kept below 10 muCi/Ci 90Y (corrected to preparation time). Also, it was necessary to remove trace metals that interfered in the 90Y antibody radiolabeling process, giving low radiolabeling yields. Di-(2-ethylhexyl) phosphoric acid (HDEHP) in dodecane has been used routinely at ORNL to extract 90Y and thereby give a product that meets the radiochemical purity required with respect to 90Sr. Methods were also developed to remove interfering trace elements to provide acceptable labeling yields.