Radio isotopes are used in the following techniques except:
C i.e. ELISA Concept: ELISA (Enzyme Linked Inununoabsorbent Assay) is an enzyme based immnoassy; the similar test which uses radioactive isotope in place of enzyme is known as Radioimmunoassay (RIA) So I don't think any need of learning that- Nucleic acid sequencing, mass spectroscopy & RIA are tests using radio isotopes.
Mass spectroscopy
RIA
ELISA
Sequencing of nucleic acid