A folate receptor-targeting radiopharmaceutical consisting of a folate-containing tetrapeptide chelator to which technetium Tc 99m is linked. The folate component of folate receptor-targeted technetium Tc 99m EC20 binds to folic acid receptors, which are frequently upregulated in many types of tumor cells and activated macrophages. Gamma scintigraphy may then be used to image folate receptor-positive tumors.