BETA COUNTER

Typical Number in Hospital: 2

Cost Bands: 5

References: 3

The detection and measurement of radio-labelled compounds emitting gamma rays is usually achieved using a sodium iodide scintillation crystal in conjunction with a photomultiplier (PM) tube. At lower energies (below 20 keV) and with beta rays (up to 500 keV), the rays are excessively attenuated. This problem is overcome by mixing the scintillator with the sample in a light- tight vial in intimate contact with the PM tube. This is the principle of the beta counter, or liquid scintillation counter.

The scintillators are complex organic molecules, and secondary scintillators may be used to convert the wavelength to match the PM tube. The devices are intended for counting samples containing beta-emitting radionuclides such as tritium and carbon 14. They are found in hospital departments such as chemical pathology, nuclear medicine, and immunology.