Comparison of thermoluminescence response of different sized Ge-doped flat fibers as a dosimeter

Prime dosimetric properties, including dose-response, linearity with dose, energy response, fading and threshold doses were investigated for three different dimension Ge-doped flat fibers. The results of measurement were also compared with two of the more commonly used standard TLD media, TLD-100 (LiF:Mg,Ti-7.5%(LiF)-Li-6) and TLD-700 ((LiF)-Li-7:Mg,Ti 99.9%(LiF)-Li-7) chips. The flat cross-section samples (60 x 180) mu m(2), (100 x 350) mu m(2) and (200 x 750) mu m(2) were fabricated using the Modified Chemical Vapor Deposition (MCVD) process and pulled from the same preform. In the study, all flat fiber samples provided good linear dose-response for the photon and electron beams generated using a medical linear accelerator (LINAC), for doses in the range 0.5-8 Gy. Among the samples, the smallest dimension flat fiber provided the best response, with a sensitivity of some 61% and 54%, respectively of that of the TLD-100 and TLD-700 chips. The energy responses of the samples were studied for various photon (6 MV, 10 MV) and electron (6 MeV, 9 MeV) beam energies. it fading of around 20% was observed over a period of thirty (30) days. These favorable TL characteristics point towards promising development of Ge-doped flat fibers for use in radiotherapy dosimetry. (C) 2015 Elsevier Ltd. All rights reserved.