Final answer:
Radioimmunoassay (RIA) is a competitive binding assay based on immunology principles, using radioactive isotopes to measure specific substances, key in cancer screening and various diagnoses.
Step-by-step explanation:
The radioimmunoassay (RIA) technique, grounded in immunology principles, is a competitive binding assay used for precision measurement and detection of specific substances within a sample. RIA was a groundbreaking development in nuclear medicine, crafted by Rosalyn Sussman Yalow and Solomon Berson in the 1950s. It utilizes radioactive isotopes for evaluation, which has notably revolutionized fields such as endocrinology. In this method, a sample containing a radioactive isotope is prepared and exposed to a known quantity of antibodies. The reaction allows for the measurement of unbound antibodies, indicating the concentration of the target substance. This assay is pivotal in areas like cancer screening, hepatitis diagnosis, and narcotics investigation.
For instance, testing for progesterone concentration involves creating an antigen-antibody complex with antibodies attached to the hormone in a blood sample. Once radio-labeled antibodies are added, they bind to the progesterone forming a complex that is detectable by means such as a scintillation counter. Techniques like this have significantly expanded the capabilities of disease diagnosis and medical research.