Long-term fading of LiF:Mg, Cu, P and LiF:Mg, Ti thermoluminescence detectors with standard and modified activator composition

Ptaszkiewicz, Marta

doi:10.1016/j.radmeas.2007.01.082

Cited by 12 publications

(2 citation statements)

References 7 publications

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“…It has also been observed that two month fading of the TL peak 'B' (Obryk,2010) does not differ significantly from fading of basic peaks of LiF:Mg,Cu,P detectors reported by Ptaszkiewicz (2007). Our recent data, which are still under detailed evaluation, also indicate that the TL peak 'B' intensity was not altered substantially eight years after exposure, on the contrary it even seems as amplification of the TL peak 'B' occurred, and only low temperature peaks were suppressed.…”

Section: Tl Glow-curves For Different Radiation Typesmentioning

confidence: 81%

On LiF:Mg,Cu,P and LiF:Mg,Ti phosphors high & ultra-high dose features

Obryk

Khoury

Barros

et al. 2014

Radiation Measurements

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HIGHLIGHTS• TL peak 'B' occurs for LiF:Mg,Cu,P after high doses of all radiation types.• Highly irradiated LiF:Mg,Ti glow-curve shape depends on the radiation quality.• High dose features of both phosphors are significantly different in many aspects.• Associated PL/TL high-dose measurements are possible using LiF:Mg,Cu,P.• Dopants role is crucial for high-dose features of lithium fluoride based phosphors. AbstractLiF:Mg,Ti and LiF:Mg,Cu,P are well known thermoluminescence (TL) dosimetry materials since many years. A few years ago their properties seemed well known and it was widely believed that they are not suitable for the measurement of doses above the saturation level of the TL signal, which for both materials occur at about 1 kGy.The high-dose high-temperature TL emission of LiF:Mg,Cu,P observed at the IFJ in 2006, which above 30 kGy takes the form of the so-called TL peak 'B', opened the way to use this material for measuring the dose in the high and ultra-high range, in particular for the monitoring of ionizing radiation around the essential electronic elements of high-energy accelerators, also fission and fusion facilities, as well as for emergency dosimetry. This discovery initiated studies of high and ultra-high dose characteristics of both these phosphors, which turned out to be significantly different in many aspects. These studies not only strive to refine the method for measuring high doses based on the observed phenomenon, but also, and perhaps above all, bring us closer to understanding its origin and essence. This manuscript aims to review existing research data on the high and ultra-high dose features of both LiF based phosphors.

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Section: Tl Glow-curves For Different Radiation Typesmentioning

confidence: 81%

On LiF:Mg,Cu,P and LiF:Mg,Ti phosphors high & ultra-high dose features

Obryk

Khoury

Barros

et al. 2014

Radiation Measurements

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“…Characterization of TLDs is required for accurate dosimetry, i.e. the sensitivity of the thermoluminescent (TL) material, the energy and dose responses, the stability and reproducibility of results, and thermal fading [114][115][116] of the detector must be evaluated for a given kind of ionizing radiation. MCP and MT dosimeters of standard thicknesses from different manufacturers have been tested along the past years to low-energy x and gamma rays [117][118][119] , conventional megavoltage (MV) photon 47;120-122 and electron 47;123-126 beams, neutrons 127;128 , alpha particles 129 , beta electrons, mixed fields 127;130-134 and high-energy particle beams (i.e.…”

Section: Characterizationmentioning

confidence: 99%

Absorbed dose assessment in the presence of tissue heterogeneities in external radiotherapy

Bueno Vizcarra

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The absorbed dose assessment in the presence of tissue heterogeneities in external radiotherapy is an issue that has concerned the medical physics community for almost three decades and it is still a matter of concern. Aiming to obtain dose distributions in clinically-acceptable computation times, analytical dose calculation algorithms integrated in treatment planning systems based their calculations on water-equivalent properties and elemental compositions of each material are disregarded despite the fact that radiation interaction processes strongly depend on them. This approximation provides reasonable accuracy in water-like tissues but the reliability of predicted dose distributions in the patient might be questioned when the radiation beam is traversing complex density heterogeneities, such as air, lung or bone. Experimental verification of dose calculation algorithms is essential and ionization chambers (IC) are the reference detectors for this purpose. However, correction factors to determine the absorbed dose in materials other than water are unknown for most IC types and therefore, they cannot procure reliable measurements in heterogeneous media. Monte Carlo (MC) simulations offer a high precision in dose calculation by tracking all particles individually taking into account the specific properties of each material. Unfortunately, accuracy and computation speed are inversely proportional and MC-based approaches generally entail long calculation times, unaffordable in the clinical routine. Nevertheless, for the cases where the expected errors in the predicted dose distributions during treatment planning are significant, i.e. when the radiation beam path is highly inhomogeneous, the benefit of resorting to MC dose calculations to achieve higher accuracy would be undoubtedly worth a presumably long computation time. In this thesis the suitability of several detectors to accurately determine the absorbed dose in the presence of high-density heterogeneities was evaluated. Ultra-thin thermoluminescent detectors (TLDs) and radiochromic films were considered as potential candidates for entailing low perturbation effects. MC dose calculations enabled to validate and understand the experimental results. Further, both dosimetric techniques were employed to thoroughly examine the behavior of a recently-released non-analytical dose calculation algorithm (AXB)¿which copes with the elemental composition of materials and thus, is claimed to yield promising results¿in heterogeneous phantoms. Finally, a fast algorithm named the heterogeneity index (HI) was developed to quantify the level of patient tissue heterogeneities traversed by the radiotherapy beam. The validity of this HI to easily predict the accuracy of dose distributions based on analytical dose calculations was analyzed by evaluating the correlation between the HI and the dose uncertainties estimated by using MC as the reference. The results show that a detector of 50µm thickness can provide reliable absorbed dose measurements in high-density heterogeneities since perturbation correction factors are unneeded. AXB was found to provide comparable accuracy to MC dose calculations in the presence of heterogeneities but uncertainties in the material assignment procedure might lead to significant changes in the dose distributions, which deserves a word of caution when carrying out experimental verifications. Finally, HI was found to be a fast and good indicator for the accuracy of dose delivery in terms of tumor dose coverage. Accordingly, HI can be implemented in the clinical routine to decide whether or not a MC dose recalculation of the plan should be considered to ensure that dose uncertainties are kept within tolerance levels. In conclusion, this thesis work tackled the main concerns on the absorbed dose calculation and measurement in the presence of tissue heterogeneities.

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Passive Dosimeters for Radiation Dosimetry: Materials, Mechanisms, and Applications

Yang,

Vrielinck,

Jacobsohn

et al. 2024

Adv Funct Materials

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Passive dosimeters enabling accurate measurement of doses from gamma rays to visible light are necessary to ensure efficient utilization of electromagnetic radiation in numerous fields like medical diagnostics and industrial manufacturing. The specific requirements for dosimeters in terms of dosimetry range, sensitivity, accuracy, and stability for each application have led to the development of various dosimeters based on new materials and new mechanisms. Here, a comprehensive review of different types of dosimeters classified according to the response signal, namely electron paramagnetic resonance, electrical, and optical, is provided. This review starts with a general introduction to dosimetry, a classification of dosimeters, and an elucidation of the necessity of dosimeters in various ranges of the electromagnetic spectrum. This is followed by an overview of the fundamental requirements of dosimeters, an explanation of the general dosimetry procedure, and the dosimetric quantities. Emphasis is given to the working mechanism, the design concept, and applications of each type of dosimeter as well as their respective strengths and drawbacks. Challenges and prospects are presented at the end of the review. This review provides an insightful overview of the material‐mechanism‐characteristics‐application relationship of different types of dosimeters that hopefully can serve as inspiration for the development of new devices.

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Long-term fading of LiF:Mg, Cu, P and LiF:Mg, Ti thermoluminescence detectors with standard and modified activator composition

Cited by 12 publications

References 7 publications

On LiF:Mg,Cu,P and LiF:Mg,Ti phosphors high & ultra-high dose features

On LiF:Mg,Cu,P and LiF:Mg,Ti phosphors high & ultra-high dose features

Absorbed dose assessment in the presence of tissue heterogeneities in external radiotherapy

Passive Dosimeters for Radiation Dosimetry: Materials, Mechanisms, and Applications

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