Characterisation of sensitive Ge-doped silica flat fibre-based thermoluminescence detectors for high resolution radiotherapy dosimetry

• Published in: Journal of Physics: Conference Series
• Main Author: Rahim A.R.A.; Zahaimi N.A.; Zin H.M.; Bradley D.A.; Mahdiraji G.A.; Rahman A.T.A.
• Format: Conference paper
• Language: English
• Published: Institute of Physics Publishing 2017
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021755745&doi=10.1088%2f1742-6596%2f851%2f1%2f012024&partnerID=40&md5=55d0abfc8b47b4e86615bde0b406bfb0

Present study focuses on characterisation of SiO2 optical fibers as a potential thermoluminescence (TL) system for radiation therapy dosimetry. Irradiations were made using 6 MV photon beams from a linear accelerator. Flat SiO2 optical fibers of various dimensions with 8% concentration of germanium doped were used. The dimensions of the flat fibers were 270x60 μm, 360x73 μm, 100x510 μm and 160x750 μm. Flat SiO2 optical fibers were characterised for TL dose response in terms of linearity, sensitivity, fading and reproducibility. The uncertainty measured was ±1 standard error of the mean and the coefficient variation was within ±4%, as required for clinical radiotherapy dosimetry. Results shown a good distribution of TL response measured by flat SiO2 optical fibers with uncertainties less than 4%. Linearity of TL comes out with a coefficient of determination (r2) of each fibers that is better than 99% which resulted in high percentage of confidence level. The loss of TL response due to fading, for photon irradiation at fixed energy and constant dose was found to be (20.4 ± 0.2)% over a post irradiation period of 30 days. The TL fading well, showing rapid loss in the first seven (7) days (17.8 ± 0.2)% followed by a more linear like loss subsequently the following day (3.2 ± 0.2)%. A perfect selection of fibers can enhance the accuracy of radiation dosimeter in order for better determination and measurement of radiation doses with a linear response over wide range therapeutic dose. © Published under licence by IOP Publishing Ltd.