Enhanced TL response due to radiation induced defects in Ge-doped silica preforms

Shafiqah, A.S. Siti; Amin, Yusoff Mohd; Nor, Roslan Md; Tamchek, N.; Bradley, D.A.

doi:10.1016/j.radphyschem.2015.02.015

Cited by 9 publications

(4 citation statements)

References 16 publications

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“…Our first such studies of Ge-doped glass concerned use of commercially available SiO2 (silica) fibres, harnessing the centrally located Ge dopant introduced within the core to provide for the total internal reflection needed for light transport. The Ge significantly increases the number of defect centres within the glass, fortuitous in increasing the TL response [ 10 , 15 , 30 – 32 ]. To-date the majority of our studies have made use of commercially available circular cross-section telecommunication fibres, widely available and offering advantageous response in radiotherapy dosimetry applications, comparison being made against competing passive dosimetric systems, TLD or otherwise [ 10 , 14 – 15 , 26 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

Tailored Ge-doped fibres for passive electron radiotherapy dosimetry

et al. 2020

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Study has been made of the thermoluminescence yield of various novel tailor-made silica fibres, 6 and 8 mol % Ge-doped, with four differing outer dimensions, comprised of flat and cylindrical shapes, subjected to electron irradiation. Main thermoluminescence dosimetric characteristics have been investigated, including the glow curve, dose response, energy dependence, minimum detectable dose, effective atomic number, linearity of index and sensitivity of the fibres. The studies have also established the uncertainties involved as well as the stability of response in terms of fading effect, reproducibility and annealing. In addition, dose-rate dependence was accounted for as this has the potential to be a significant factor in radiotherapy applications. The 6 and 8 mol % fibres have been found to provide highly linear dose response within the range 1 to 4 Gy, the smallest size flat fibre, 6 mol% Ge-doped, showing the greatest response by a factor of 1.1 with respect to the highly popular LiF phosphor-based medium TLD100. All of the fibres also showed excellent reproducibility with a standard deviation of < 2% and < 4% for 6 and 8 mol % Ge-doped fibres respectively. For fading evaluation, the smallest 6 mol% Ge-doped dimension flat fibre, i.e., 85 × 270 μm displayed the lowest signal loss within 120 days post-irradiation, at around 26.9% also showing a response superior to that of all of the other fibres. Moreover, all the fibres and TLD-100 chips showed independence with respect to electron irradiation energy and dose-rate. Compared with the 8 mol% Ge-doped optical fibres, the 6 mol% Ge-doped flat optical fibres have been demonstrated to possess more desirable performance features for passive dosimetry, serving as a suitable alternative to TLD-100 for medical irradiation treatment applications.

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Section: Introductionmentioning

confidence: 99%

Tailored Ge-doped fibres for passive electron radiotherapy dosimetry

et al. 2020

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“…Here it is important to note that the process of collapsing the initially hollow circular cross-section doped silica preform into a solid flat fiber is brought about by application of a vacuum ( Figure 1 , providing an example of the flat fiber shape). This has been demonstrated elsewhere to generate strained inner-contact surface defects [ 9 , 10 , 12 ]. These newly generated defects add substantially to the relative sensitivity of the fibers.…”

Section: Introductionmentioning

confidence: 88%

“…The fiber dosimeters studied herein were fabricated in the University of Malaya, at the Department of Electrical Engineering, using the fiber pulling tower located there. A review of the process followed in obtaining these flat fibers from the starting silica preform is covered in A. Shafiqah et al ., Dambul et al ., and Siti Abdul Sani et al ., [ 9 , 12 , 13 ], it also being noted that in the process of the fiber drawing additional defects can be induced. The doped optical fiber samples, of nominal length 6 mm (obtained using an optical fiber cleaver), were of four specific cross-sectional dimensions: 85 × 270 µm, 100 × 350 µm, 165 × 620 µm and 200 × 750 µm, the larger dimension in each pairing corresponding to the length along the contact surface axis, while the smaller dimension corresponds to the thickness transverse to this contact surface.…”

Section: Methodsmentioning

confidence: 99%

The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation

Nawi

Wahib

Zulkepely

et al. 2015

Sensors

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Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using a 60Co source, the samples were irradiated to doses within the range 1 to 10 Gy. Prior to irradiation, the flat fibers were sectioned into 6 mm lengths, weighed, and annealed at 400 °C for 1 h. TL readout was by means of a Harshaw Model 3500 TLD reader, with TLD-100 chips (LiF:Mg, Ti) used as a reference dosimeter to allow the relative response of the fibers to be evaluated. The fibers have been found to provide highly linear dose response and excellent reproducibility over the range of doses investigated, demonstrating high potential as TL-mode detectors in radiation medicine applications. Mass for mass, the results show the greatest TL yield to be provided by fibers of the smallest cross-section, analysis indicating this to be due to minimal light loss in transport of the TL through the bulk of the silica medium.

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“…Most of the TL dosimeters will come with some impurities which will form an electron trap in TL band models. The impurities or dopants are a chemical substance which deliberately introduced into the TL base materials to increase the defects and also helps to improve the dosimetric characteristics of the dosimeters [1][2][3]. Lithium fluoride (LiF) is one of the most widely used dosimeters in medical which comes with various impurities such as magnesium and titanium.…”

Section: Introductionmentioning

confidence: 99%

Evaluation on Thermoluminescence Kinetic Parameters of Ge-Doped Cylindrical Fibre Dosimeter by Computerised Glow Curve Deconvolution Technique

Fadzil

Min

Ariffin

et al. 2019

Proceedings of the Second International Symposium on Radiation Detectors and Their Uses (ISRD2018)

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The shapes of the glow curve obtained from computerized glow curve deconvolution (CGCD) of Ge-doped cylindrical fibres (CF) were evaluated to determine the properties of kinetic parameters of Ge-doped CF as a potential thermoluminescence (TL) dosimeter using WinGCF software. The Ge-doped CF was irradiated to 6 MV and 10 MV photon beams generated by medical linear accelerator with dose ranging from 100 cGy to 300 cGy. It was observed that the maximum intensity of the glow curve for CF was located between 259 °C to 271 °C for 6 MV and 253 °C to 269 °C for a 10 MV irradiation. After deconvolution was done, the Ge-doped CF glow curve appeared as five individual glow peaks; indicate that the peak height is highly dependent on the dose. As the dose increases, area under the curve increases, suggesting the increment in number of electron ejected from the traps.

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Enhanced TL response due to radiation induced defects in Ge-doped silica preforms

Cited by 9 publications

References 16 publications

Tailored Ge-doped fibres for passive electron radiotherapy dosimetry

Tailored Ge-doped fibres for passive electron radiotherapy dosimetry

The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation

Evaluation on Thermoluminescence Kinetic Parameters of Ge-Doped Cylindrical Fibre Dosimeter by Computerised Glow Curve Deconvolution Technique

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