bild

Personal radiation dose meter. (dosimeter). This is a miniature thermoluminescent dosimeter (TLD), designed to be worn on a finger. A TLD is a reusable dosimeter that uses lithium fluoride to measure the radiation dose. After use, the lithium fluoride is heated to over 250 degrees Celsius, at which point it gives out an amount of light proportional to the radiation dose received. Dosimeters are worn by people who are exposed to radiation regularly during their work. There are strict limits to the amount of radiation to which nuclear industry workers, and those working with radioactive materials in laboratories, can be exposed. Personal dosimeters are used to keep track of an individual's overall exposure levels. (KEYSTONE/SCIENCE PHOTO LIBRARY/HEALTH PROTECTION AGENCY)