See Contrast Agents.

(EIA) Enzyme immunoassays have been developed as an alternative to radioimmunoassays. These methods use an enzyme to label either the antibody or antigen. The sensitivity of an enzyme immunoassay is similar to that for a radioimmunoassay, without the danger of radiation. One of the most widely used EIA for detection of infectious diseases is the ELISA (Enzyme Linked lmmuno Sorbent Assay) method.

See also Fluorescent Immunoassay.

(ELISA) An enzyme linked immuno sorbent assay, also called ELISA, or enzyme immunoassay (EIA) is a diagnostic tool to measure the concentration of a particular molecule.

See also Radioimmunoassay.

Epithermal neutrons are unbound moderately severe neutrons. The energy of epithermal neutrons is in the range from 0.025 to 1 eV. Unbound neutrons are produced in fission and in some radioactive decay processes.

See also Neutron Activation Analysis, Neutron Capture.

(ENAA) See Neutron Activation Analysis.