(... ih-brih-TOO-moh-mab ty-UK-seh-tan) A radiolabeled monoclonal antibody used to find certain types of B-cell non-Hodgkin lymphoma. It is also being studied in the diagnosis of other types of B-cell tumors. 111In-ibritumomab tiuxetan is made up of the monoclonal antibody ibritumomab plus the radioisotope indium In 111. It binds to a protein called CD20, which is found on B cells. A machine is used to find which cells in the body have taken up 111In-ibritumomab tiuxetan. 111In-ibritumomab tiuxetan is a type of radioimmunoconjugate. Also called 111In-Zevalin and indium In 111-ibritumomab tiuxetan.