TLD ring badges are very important for individuals involved in eluting generators, preparing kits, and injecting patients.

Monitoring Devices: TLD

• The thermoluminescent dosimeter depends on thermoluminescent phosphors, such as lithium fluoride, that trap electrons freed by radiation exposure.
  

• The trapped electrons release light when the application of heat frees the electrons, returning them to stable energy states. The process can be repeated many times. 
  

• Instead of reading the blackness (optical density) of a film, the amount of light released versus the heating of the individual pieces of thermoluminescent material is measured as a "glow curve" which is then related to the radiation exposure.
  

• Lithium fluoride in the form of powder compressed into pellets has advantages over film badges by being tissue equivalent, by having an exposure range from a few hundredths of a millisievert to over 100 Sv (10000 rem), by exhibiting little fading over time in storage at room temperature and by being free of many of the problems associated with film.
  

• In the badge, a pellet is placed behind each of the filters so that radiation energy information is obtained as well as consistent readings. The ability to reuse the pellets is also an advantage.
  

• If the lithium is enriched with Li-6, the lithium fluoride becomes very sensitive to thermal neutron interaction and a pair of pellets (one enriched and the other not enriched) can provide neutron exposure information.