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

Nawi, Siti Nurasiah Binti Mat; Wahib, Norfadira; Zulkepely, Nurul Najua; Amin, Yusoff Bin Mohd; Min, Ung Ngie; Bradley, D.A.; Nor, Roslan Bin Md; Maah, Mohd Jamil

doi:10.3390/s150820557

Cited by 18 publications

(2 citation statements)

References 18 publications

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“…Figure 3 shows the glow curves of PCFc-GE-B irradiated at ∼40 keV mean x-ray energy, with doses ranging from 0.5 mGy to 10 mGy, providing a representation of all the measured PCFc samples. From the figure, it is clear that the peak height intensity of the glow curve and area under the glow curve are both dependent on the amount of dose given to the sample, corresponding well with the results of previous studies (Hashim et al 2015, Nawi et al 2015. The area under the curve represents the number of electrons released from traps and thus, by association, the radiation energy deposited, while the peak height is indicative of the maximum number of electrons traps released.…”

Section: Laboratory Work: Calibration and Fading Study Of Tld Samples...supporting

confidence: 86%

Environmental monitoring through use of silica-based TLD

et al. 2017

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The sensitivity of a novel silica-based fibre-form thermoluminescence dosimeter was tested off-site of a rare-earths processing plant, investigating the potential for obtaining baseline measurements of naturally occurring radioactive materials. The dosimeter, a Ge-doped collapsed photonic crystal fibre (PCFc) co-doped with B, was calibrated against commercially available thermoluminescent dosimetry (TLD) (TLD-200 and TLD-100) using a bremsstrahlung (tube-based) x-ray source. Eight sampling sites within 1 to 20 km of the perimeter of the rare-earth facility were identified, the TLDs (silica- as well as TLD-200 and TLD-100) in each case being buried within the soil at fixed depth, allowing measurements to be obtained, in this case for protracted periods of exposure of between two to eight months. The values of the dose were then compared against values projected on the basis of radioactivity measurements of the associated soils, obtained via high-purity germanium gamma-ray spectrometry. Accord was found in relative terms between the TL evaluations at each site and the associated spectroscopic results. Thus said, in absolute terms, the TL evaluated doses were typically less than those derived from gamma-ray spectroscopy, by ∼50% in the case of PCFc-Ge. Gamma spectrometry analysis typically provided an upper limit to the projected dose, and the Marinelli beaker contents were formed from sieving to provide a homogenous well-packed medium. However, with the radioactivity per unit mass typically greater for smaller particles, with preferential adsorption on the surface and the surface area per unit volume increasing with decrease in radius, this made for an elevated dose estimate. Prevailing concentrations of key naturally occurring radionuclides in soil, Ra,Th and K, were also determined, together with radiological dose evaluation. To date, the area under investigation, although including a rare-earth processing facility, gives no cause for concern from radiological impact. The current study reveals the suitability of the optical fibre based micro-dosimeter for all-weather monitoring of low-level environmental radioactivity.

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Section: Laboratory Work: Calibration and Fading Study Of Tld Samples...supporting

confidence: 86%

Environmental monitoring through use of silica-based TLD

et al. 2017

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“…Further studies have involved use of different medical techniques such as intensity-modulated radiotherapy (IMRT) verification (Noor et al, 2010), brachytherapy dosimetry (Issa et al, 2012;Palmer et al, 2012), and interface radiation applications (Abdul Rahman et al, 2011). Investigations have further been carried out on undoped flat fibres (Abdul Sani et al, 2014) and doped flat fibres (Nawi et al, 2015;Begum et al, 2015). In regard to detection limits, in studies of clinical diagnostic X-ray dosimetry, determined minimum detectable doses (MDDs) of 0.1 μGy and 1.0 μGy for GeB co-doped flat fibres (FF) and Ge-doped discs respectively.…”

Section: Introductionmentioning

confidence: 99%

GeB flat fibre TL dosimeters for in-vivo measurements in radiosurgery

Alyahyawi

Dimitriadis

Nisbet

et al. 2021

Radiation Physics and Chemistry

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Noting an increase in demand for procedures involving clinical radiosurgery we seek to develop a high spatial resolution thermoluminescence dosimeter (TLD) to allow conduct of in vivo dose verification measurements. An associated need is for a dynamic dose range exceeding that of the well-established LiF (Mg,Ti) phosphor TLD-100, with in particular the latter being limited in performance at the elevated doses seen in radiotherapy. The work investigates the performance of a novel GeB co-doped Flat Fibre (GeB-FF) fabricated using the modified chemical vapour deposition (MCVD) process, the hollow capillary optical fibres (COF) produced from this being collapsed down into flat fibres (FF) to create strain-related defects. This process has already been demonstrated to increase the low dose sensitivity of optical fibres, notably at diagnostic x-ray potentials, with Minimum Detectable Dose (MDD) values of down to 0.1 μGy. The intent of present work, conducted as a component of a safety audit, part of the hospital periodic radiation protection quality assurance program, has been to examine and compare the performance of the two forms of TL dosimeter, GeB-FF and TLD-100, measuring scattered radiation resulting from cranial cavity radiosurgery procedures. The dosimeters were placed on the neck, chest and pelvis of 20 patients. Using both types of dosimeter, raw dose values at each site show general accord ( 3 mGy at 1 ), covering mean doses ranging from some 10 mGy to less than 1 mGy, representing doses of < 1% to < 0.1 % of prescribed dose at the treatment site. GeB-FF results uncorrected for energy response show absorbed doses greater than that using TLD-100, by factors of some 1.4, 1.2 and 1.5 for the pelvis, chest and neck respectively; energy corrections have been shown elsewhere to provide for much closer agreement.

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Natural dead sea salt and retrospective dosimetry

Wahib

Sani

Ramli

et al. 2020

Radiat Environ Biophys

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Accidents resulting in widespread dispersal of radioactive materials have given rise to a need for materials that are convenient in allowing individual dose assessment. The present study examines natural Dead Sea salt adopted as a model thermoluminescence dosimetry system. Samples were prepared in two different forms, loose-raw and loose-ground, subsequently exposed to 60 Co gamma-rays, delivering doses in the range 2-10 Gy. Key thermoluminescence (TL) properties were examined, including glow curves, dose response, sensitivity, reproducibility and fading. Glow curves shapes were found to be independent of given dose, prominent TL peaks for the raw and ground samples appearing in the temperature ranges 361-385 ºC and 366-401 ºC, respectively. The deconvolution of glow curves has been undertaken using GlowFit, resulting in ten overlapping first-order kinetic glow peaks. For both sample forms, the integrated TL yield displays linearity of response with dose, the loose-raw salt showing some 2.5 × the sensitivity of the ground salt. The samples showed similar degrees of fading, with respective residual signals 28 days post-irradiation of 66% and 62% for the ground and raw forms respectively; conversely, confronted by light-induced fading the respective signal losses were 62% and 80%. The effective atomic number of the Dead Sea salt of 16.3 is comparable to that of TLD-200 (Z eff 16.3), suitable as an environmental radiation monitor in accident situations but requiring careful calibration in the reconstruction of soft tissue dose (soft tissue Z eff 7.2). Sample luminescence studies were carried out via Raman and Photoluminescence spectroscopy as well as X-ray diffraction, ionizing radiation dependent variation in lattice structure being found to influence TL response.

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

Cited by 18 publications

References 18 publications

Environmental monitoring through use of silica-based TLD

Environmental monitoring through use of silica-based TLD

GeB flat fibre TL dosimeters for in-vivo measurements in radiosurgery

Natural dead sea salt and retrospective dosimetry

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