Film badge dosimeter
Film badge ( colloquially film badges or X-ray plaques ) are detection devices for ionizing radiation, the use of the blackening of photographic material by the radiation. They are used in the dose range between 0.1 mSv and 1 Sv and are suitable for X-rays and gamma rays between 20 keV and 3 MeV. At the dose determination with film dosemeters is a storing and integrating method. By using various radiation converter (filter ) in the housings ( Ansteckplakette ), these dosimeters are also applicable to other types of radiation such as alpha radiation, beta radiation, and neutron radiation.
Construction
There are on the market various types of film dosemeters available, so there is no uniform structure of a Filmdosimeters. The used and approved in Germany film dosimeter is manufactured by Agfa. In the Dosimeterhülle polyethylene two detectors, a less sensitive film (u - eFilm ) for high doses and a sensitive film ( e ) film are included for low doses. Furthermore, for separating the detectors, an intermediate layer of paper exist.
The film badge is worn on the body in a cassette containing the filter elements made of different metals. These filters enable us to determine the angle of the incident radiation and also be used to measure tissue equivalent values among the filter elements.
Evaluation
Before evaluation, the films are removed from the Dosimeterhülle and developed. Since the detectors are extremely sensitive to light, the unpacking to be done in a darkroom. After unpacking the films are made by a developing bath. Due to the chemical development process blackening at the points are visible on the film, where the film has been exposed to ionizing radiation in touch. In order to determine the dose to the film, the measurement of the optical density by a densitometer. The result of the evaluated dose is reported to the Radiation Safety Officer.
Application
Film dosimeters are used in personal dosimetry, particularly for monitoring radiation- exposed persons by official monitoring sites.