2. Autoradiography on film

2.1 Principle

Photographic emulsions consist of silver halide grains or crystals deposited on a film (Hyperfilm©). The sample is brought into contact with the film. Many silver ions are reduced (by collision) to metallic silver atoms by beta particles or gamma radiation. When beta particles or gamma radiation pass through the photographic emulsion, energy is lost in a series of interactions with the electrons in the silver halide crystals. The energy of a single beta particle or gamma ray is sufficient to make each crystal developable (figure 1 and table 1 ).