A personal dosimeter which uses solid crystals to monitor radiation absorbed dose. Typically, these crystals are composed of lithium fluoride (LiF) and exhibit radiation absorption characteristics similar to that of human tissue. The ionizing radiation produces small local crystal defects which are stable until the crystal is heated. When the crystal is heated to temperatures of approximately 200°C, the defects are removed and the associated energy is released in the form of light. The amount of light produced is proportional to the number of crystal defects induced which in turn is related to the amount of radiation absorbed.