Abstract
We investigated the nature and significance of three radiochemical impurities that were found in a lung imaging kit using 99mTc-tin-macroaggregated albumin. The most abundant radiochemical impurity was a soluble 99mTc-labeled protein. Free pertechnetate (99mTcO4–) and reduced and hydrolyzed technetium (99mTcO2) were present in relatively low radioconcentrations. The presence of a soluble 99mTc-labeled protein in the preparation at the time of injection modified the biologic performance of the product. We suggest that, to be meaningful, a quality control program must employ assay procedures which are capable of identifying and quantitating all the significant radiochemical impurities that are present in a preparation.