UV-induced second readout of LiF thermoluminescent dosimeters in the therapeutic dose range

A previously developed technique for reading out LiF thermoluminescent dosimeters (TLD) a second and subsequent time by means of ultraviolet (UV)-induced repopulation of dosimetry traps was studied to determine the feasibility of maintaining a second readout capability in a radiotherapy clinical setting. It was found that with grouping of the TLDs according to second readout sensitivity, the UV-induced readout attained a precision comparable to that of the initial readout. However, the UV-induced TL response retained a strong previous dose memory following a standard high-temperature anneal, and routine calibration before each reuse is recommended.