Recombinant Anti-CEA x Anti-DTPA Bispecific Antibody (Bibody) is a Fab-scFv format that uses heterodimeric Fab as a scaffold, and a scFv region linked to one of its heavy (Fd) or light (L) chain. The scFv of the anti-CEA specificity is fused to the anti-DTPA heavy or light chain of the Fab. 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.