(TLD) A thermoluminescent dosimeter contains a crystalline material (lithium fluoride, phosphor) for measuring radiation dose. TLDs are usually small crystals measuring 3 mm square by 1 mm thickness. Additional filters (absorbers) help to characterize the types of the impinging radiation. When heated, TLD crystals that have been exposed to ionizing radiation give off light proportional to the received energy.

The dose limit is the highest value of an applied or allowed radiation exposure. The radiation dose is limited in order to prevent the occurrence of radiation-induced deterministic effects or to limit the probability of radiation-related stochastic effects to an acceptable level.

See also Whole Body Counter, Thermoluminescent Dosimeter, Dosimetrist, Annual Limit On Intake, Committed Effective Dose Equivalent, Computed Tomography Dose Index, Directional Dose Equivalent, Doubling Dose.