An assay based on the reversible and non-covalent binding of an antigen by a specific antibody labelled with a radioactive nuclide as a tracer.
Source:
PAC, 1994, 66, 2513. 'Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)' on page 2520 (https://doi.org/10.1351/pac199466122513)