The response of LiF:Mg, Ti detectors in a 7 MeV photon beam

In this paper we have studied the response of the LiF: Mg, Ti thermoluminescent detectors (TL) and bracelet dosimeters to a 7 MeV photon beam in order to extend their use from personnel dosimetry to the dosimetry of relativistic electrons and X-ray beams. The detectors and dosimeters were irradiated in a mixed radiation field (about 60% photon contribution) generated by the 7 MeV NILPRP-Bucharest linear accelerator. The photon equivalent dose reference value within 0.01 Sv - 6 Sv interval was determined with a maximum uncertainty of ± 3%. Separate measurement of photon and electron equivalent doses was made by a bracelet-type dosimeter which contains two detectors. The response values at a reference value of 0.01 Sv were previously determined for photons, using X-ray (29-123 keV) and γ ray (662 keV, 137 Cs) reference fields and for electrons, using a 90(Sr + Y) standard source. The measurement results showed that the response of the LiF: Mg, Ti TL detectors built in our institute and of the dosimeters using these detectors do not depend on the photon energy. The final conclusion is that TL dosimeters using LiF: Mg, Ti detectors are suitable for the characterization of the accelerator fields, for monitoring the equivalent dose value in radiotherapy and for operator personnel dosimetry. Due to their accuracy and miniaturization degree the detectors are suitable for 'in vivo' dosimetry. (authors)