Film badge dosimeter

The film badge dosimeter or film badge is a personal dosimeter used for monitoring cumulative radiation dose due to ionizing radiation. The film badge dosimeter or film badge is a personal dosimeter used for monitoring cumulative radiation dose due to ionizing radiation. The badge consists of two parts: photographic film, and a holder. The film emulsion is black and white photographic film with varying grain size to affect its sensitivity to incident radiation such as gamma rays, X-rays and beta particles. . After use by the wearer, the film is removed developed and chemically developed to measure exposure. When the film is irradiated, an image of the protective case is projected on the film. Lower energy photons are attenuated preferentially by differing absorber materials. This property is used in film dosimetry to identify the energy of radiation to which the dosimeter was exposed. Some film dosimeters have three emulsions, one for low-dose and the other for high-dose measurements. These two emulsions can be on separate film substrates or on either side of a single substrate. Knowing the energy allows for accurate measurement of radiation dose. The device was developed by Ernest O. Wollan whilst working on the Manhattan Project, though photographic film had been used as a crude measure of exposure prior to this.