Effect of photon irradiation on the thermoluminescence response of optical fibres

Abstract

Studies on silica glass (SiO2) optical fibre as thermoluminescent materials for medical radiation dosimetry have been conducted by several research groups. This study focuses on the thermoluminescence (TL) response, linearity, sensitivity, dose response, fading, reproducibility and minimum detectable dose of 12 optical fibres sample namely Ge (A) Batch 1, 2 and 3, Ge (B), Multi Photonic Crystal Fibre (MPCF, 220 µm), Multi Photonic Crystal Fibre (MPCF, 2 mm), photonic crystal fibres (PCF), Dummy Flat Fibre (DFF), Flat fiber, Photosensitive Flat Fibre (PFF), Erbium (Er) and Aluminium/ Thulium (Al + Tm) doped optical fibre. A comparison was performed with TLD-100 (chips) to obtain the best TL response among the samples. Irradiation were performed with 6 and 10 MV photons covering the dose range of 1 Gy to 4 Gy by using linear accelerator machine Elekta SynergyTM at Pantai Hospital, Kuala Lumpur and Varian Model 2100C linear accelerator at University Malaya Medical Centre (UMMC). The comparisons of TL response with different model linear accelerators involved in this research were also performed. The results show that the highest sensitivity was obtained by using TLD-100, followed by PFF, Flat, Ge (A) Batch 1, MPCF (2 mm), Ge (A) Batch 3, Ge (A) Batch 2, DFF, Al+Tm, Ge (B), Er, MPCF (220 µm) and PCF. The fading of 5 optical fibres Ge (A) Batch 1, PFF, Er, Flat Fibre and PCF were determined and the loss of the TL signal for these TL materials were 10%, 29%, 30%, 30% and 43%, respectively. The dopant concentrations of Ge (A) Batch 1, Ge (B) and Er were found to be in the range of 0.03-0.72 mol % while the Zeff was in the range of 11.9-17.1. These TL materials have great potential to be introduced as new radiation dosimeters.