What is the principle behind using film badges for radiation monitoring?

Film badges operate on the principle that they contain a special film that is sensitive to ionizing radiation. When this film is exposed to radiation, it undergoes a chemical change that causes it to darken, much like how photographic film reacts to light. The amount of darkening on the film correlates with the level of radiation exposure the badge has received; greater exposure leads to more pronounced darkening.

After the film badge is processed, the degree of darkening is measured to quantify the radiation dose experienced. This method allows for personal dosimetry in environments where radiation exposure is a concern, making film badges a reliable tool for monitoring individual exposure levels over time.