Gamma counter

A gamma counter is a machine to measure gamma radiation emitted by a radionuclide. A large number of samples are placed in sealed vials or test tubes, and move along a serpentine track on a horizontal plane. One at a time, they move down inside a shielded detector, set to measure specific energy windows characteristic of the particular isotope. Depending on the half-life and concentration of the sample, measurement times vary from 0.02 minute to one minute. Gamma counters are standard tools used in the research and development of new radioactive compounds used for diagnosing and treating disease, (as in PET scanning). Gamma counters are used in radiobinding assays and in radioimmunoassays (RIA).