Anti-CEA x Anti-DTPA Bispecific Antibody (IgG-IgG) is designed to be generated by crosslinking two full length IgGs, anti-CEA and anti-DTPA parental antibodies. A stable linkage is formed between the two antibodies. 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.