A lung counter is a system consisting of a radiation detector, or detectors, and associated electronics that is used to measure radiation emitted from radioactive material that has been inhaled by a person and is sufficiently insoluble as to remain in the lung for weeks, months, or years.[1] They are frequently used in occupations where workers may be exposed to radiation.[2]
The lung counter may be placed on or near the body.[1] These systems are also often housed in a low background counting chamber. Such a chamber may have thick walls made of low-background steel (~20-25 cm thick) and lined with lead, cadmium, tin, or polypropylene, with a final layer of copper.[3] The purpose of the lead, cadmium (or tin), and copper is to reduce the background in the low energy region of a gamma spectrum (typically less than 200 keV).[citation needed]
As a lung counter is primarily measuring radioactive materials that emit low energy gamma rays or x-rays, the phantom used to calibrate the system must be anthropometric.[citation needed] An example of such a phantom is the Lawrence Livermore National Laboratory Torso Phantom.[1]