thermoluminescent dosimetry /-lo̅o̅′mines″ənt/ [Gk, thermē + L, lumen, light; Gk, dosis, something given, metron, measure] , a method of measuring the ionizing radiation to which a person is exposed by means of a device that contains a radiation-sensitive crystalline material. The material stores the radiation’s energy by changing structure. When the material is heated at some later time, it releases the energy as ultraviolet or visible light. The light emitted is detected by a photomultiplier tube that generates an electric signal whose magnitude reflects the amount of ionizing radiation originally received.