Film dosimeter

Film dosimeters are used to measure radiation exposure to workers to monitor radiation safety and ensuring that they receive doses below the appropriate limit.

Film badges are the cheapest and most common monitoring device. They consist of a small case with a piece of film situated between filters. The sensitivity to radiation depends on photon energy with better sensitivity at the K-edge of the film. Filters are applied to assess the penetrating power of the radiation source, which provides an estimate of photon energy. The film is subsequently processed and the measured optical density provides an estimated dose based on the average photon energy.

Film badges give a permanent record of exposure, i.e. not re-usable. Furthermore, their dependence on photon energy, temperature and chemicals limit their accuracy.