Investigation of the Glow Peak Parameters, Reusability and Dosimetric Precision of LiF:Mg,Cu,P at High Heating Rates up to 20Ks-1

Ben-Amar, G.; Ben-Shachar, B.; Oster, L.; Horowitz, Y.S.; Horowitz, A.

doi:10.1093/oxfordjournals.rpd.a032726

Cited by 13 publications

(4 citation statements)

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“…After a preheat session at 135°C for10 s, the TL signal was acquired from 135°C to 240°C at a heating rate of 10°C/s. LiF (MCP) is usually annealed in an oven for 10 min at 240°C,[16–18] but deformed glow curves were noticed by following this procedure [Figure 1], which might be due to imperfect thermal transmission form metal plate container in the oven. For this reason, single chip annealing method using reader post-reading cycle (240°C for 10 s), was preferred.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of target dose based on water-equivalent thickness in external beam radiotherapy

Moghaddam¹,

Vahabi-Moghaddam²,

Sadremomtaz³

2013

J Med Phys

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In vivo dosimetry was carried out for 152 patients receiving external beam radiotherapy and the treatment sites were divided into two main groups: Thorax, Abdomen, and Pelvic (120 fields) and Head and Neck (52 fields). Combined entrance and exit dose measurements were performed using LiF: Mg, Cu, P thermoluminescent dosimeters (TLDs). Water-equivalent (effective) thicknesses and target dose were evaluated using dose transmission data. The ratio of measured to expected value for each quantity was considered as an indicator for the accuracy of the parameter. The average ratio of the entrance dose was evaluated as 1.01 ± 0.07. In the diameter measurement, the mean ratio of effective depth divided by the contour depth is 1.00 ± 0.13 that shows a wide distribution which reflects the influence of contour inaccuracies as well as tissue inhomogeneities. At the target level, the mean ratio of measured to the prescribed dose is 1.00 ± 0.07. According to our findings, the difference between effective depth and patient depth has a direct relation to target dose discrepancies. There are some inevitable sources which may cause the difference. Evaluation and application of effective diameter in treatment calculations would lead to a more reliable target dose, especially for fields which involve Thorax, Abdomen, and Pelvic.

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Section: Methodsmentioning

confidence: 99%

Evaluation of target dose based on water-equivalent thickness in external beam radiotherapy

Moghaddam¹,

Vahabi-Moghaddam²,

Sadremomtaz³

2013

J Med Phys

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“…So far, high dose measurements were performed on fresh samples and each detector was used only once, because the detectors lose their sensitivity to a large extent as a result of these measurements. The main reason is the well-known feature of LiF:Mg,Cu,P detectors: sensitivity loss when heated beyond about 270°C (Oster et al 1993, 1996, Bilski et al,1997, Ben-Amar et al, 1999. It was also reported by Meijvogel and Bos (1995) that high temperature readout is causing both reversible and irreversible changes of the sensitivity of the material.…”

Section: Introductionmentioning

confidence: 93%

“…A parameter called the Ultra-High Temperature Ratio (UHTR) was defined in order to quantify the observed changes of the MCP glow-curve shape at very high doses and very high temperatures, which allows measuring the absorbed dose in the range from 1 kGy to 1 MGy (Bilski et al, 2010;Obryk et al, 2010a). This dosimetric method was tested in a range of radiation qualities, such as gamma radiation, electron and proton beams, thermal neutron fields and high-energy mixed fields around the Super Proton Synchrotron (SPS) and the Proton Synchrotron (PS) accelerators at CERN (the European Organization for Nuclear Research) (Obryk et al, 2008(Obryk et al, , 2011b (Oster et al 1993, 1996, Bilski et al,1997, Ben-Amar et al, 1999. It was also reported by Meijvogel and Bos (1995) that high temperature readout is causing both reversible and irreversible changes of the sensitivity of the material.…”

Section: Introductionmentioning

confidence: 99%

High-dose high-temperature emission of LiF:Mg,Cu,P: Thermally and radiation induced loss & recovery of its sensitivity

Obryk¹,

Skowrońska²,

Sas-Bieniarz³

et al. 2013

Radiation Measurements

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HIGHLIGHTS:• High-dose high-temperature TL emission is present in LiF:Mg,Cu,P' glowcurves.• LiF:Mg,Cu,P can measure doses ranging from below 1 μGy to about 1 MGy.• Thermally-induced sensitivity loss of the samples can be recovered.• Sensitivity damage of the samples after high-dose measurements is Fuldy reversible.• High-dose measurements changes to the structure of the material are reversible. AbstractHighly sensitive LiF:Mg,Cu,P (MCP) detectors enable measurements of radiation doses from tens of nanograys up to a few kilograys, where the saturation of the signal of the main dosimetric peak occurs. Thanks to the recently observed high-dose high-temperature emission of MCP detectors heated to temperatures up to 600°C after exposures to radiation doses ranging from 1 kGy to 1 MGy, a new method of TL measurement of radiation doses has been recently developed at the Institute of Nuclear Physics (IFJ). This method can measure doses ranging from micrograys up to a megagray. So far, high dose measurements were performed on fresh MCP samples and each detector was used only once, because as a result of these measurements, the detectors lose their sensitivity to a large extent. In this study, a specific thermal treatment intended to fully restore the loss of MCPs TL sensitivity was sought. We have investigated several annealing procedures, applying different temperatures (from 400°C up to 700°C) for different periods of time (10-30 minutes) in argon atmosphere. In this way we were able to recover MCP sensitivity fully, allowing for reuse of the samples after high-dose irradiation and high-temperature measurement.

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“…During the past few years, considerable efforts have been made to produce new thin detector materials for personal extremity dosimetry (1) . The understanding of how different physical parameters influence the characteristics of such materials has also been improved (2)(3)(4)(5) . The main challenge has been to develop a TLD capable of measuring the personal dose equivalent at a depth of about 7 mg.cm −2 , without losing too much in sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of MCP-7s Material for Use as a Beta Extremity Dosemeter

Boschung¹,

Homsy²,

Joneja³

et al. 2000

Radiation Protection Dosimetry

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LiF:Mg,Cu,P phosphors (commercially designated as MCP-N) are very sensitive thermoluminescent detectors and are considered by many laboratories to hold great promise for low level radiation monitoring. It is their high efficiency relative to TLDs based on LiF:Mg,Ti which make MCP-N particularly attractive for low dose measurements. The currently investigated detector material made of LiF:Mg,Cu,P bears the code name MCP-7s and has a very thin active layer and consequently an improved response to low energy beta radiation. Detailed studies have been carried out to characterise MCP-7s detectors in terms of glow curve, beta and gamma response, reusability, batch homogeneity and fading. Based on the positive outcome of these investigations, the dosimetry service at PSI plans to replace the TL material LiF:Mg,Ti presently used for extremity dosimetry with MCP-7s.

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Investigation of the Glow Peak Parameters, Reusability and Dosimetric Precision of LiF:Mg,Cu,P at High Heating Rates up to 20Ks-1

Cited by 13 publications

References 0 publications

Evaluation of target dose based on water-equivalent thickness in external beam radiotherapy

Evaluation of target dose based on water-equivalent thickness in external beam radiotherapy

High-dose high-temperature emission of LiF:Mg,Cu,P: Thermally and radiation induced loss & recovery of its sensitivity

Characterisation of MCP-7s Material for Use as a Beta Extremity Dosemeter

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