Impurities in a ^99mTc Lung Imaging Kit

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.