Recombinant Anti-CEA x Anti-DTPA Bispecific Antibody (scIgG) is designed to be expressed as two chains, each chain has the same units with their parental IgG antibodies, anti-CEA and anti-DTPA IgGs. The two chains form heterodimer via Fc KIH technology. This BsAb can be used in pretargeting system of PET, radioimaging or radiotherapy. It can mediate targeting of radioactivity to tumor cells. It is designed for the research of Breast cancer; Ovary cancer; Colon cancer; Lung cancer imaging and therapy.