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S.j. Dhoble - One of the best experts on this subject based on the ideXlab platform.

  • KCl:Dy phosphor for Thermoluminescence Dosimetry of ionizing radiation.
    Luminescence : the journal of biological and chemical luminescence, 2012
    Co-Authors: P.m. Bhujbal, S.j. Dhoble
    Abstract:

    ABSTRACT: The Thermoluminescence (TL) characterizations of g-irradiated KCl:Dy phosphor for radiation Dosimetry arereported. All phosphors were synthesized via a wet chemical route. Minimum fading of TL intensity is recorded in the preparedmaterial.TLinsamplescontainingdifferentconcentrationsofDyimpuritywasstudiedatdifferentg-irradiationdoses.PeakTL intensities varied sublinearly withg-raydoseinallsamples,butwerelinearbetween0.08to0.75kGyfortheKCl:Dy(0.1mol%) sample. This material may be useful for Dosimetry within this range ofg-ray dose. TL peak height was foundto be dependant on the concentration (0.05–0.5mol%) of added Dy in the host. Copyright © 2012 John Wiley & Sons, Ltd.Keywords: Thermoluminescence (TL); ionizing radiation Dosimetry; KCl:Dy phosphor Introduction Thermoluminescence(TL)maybebroadlydefinedastheemissionof light when a solid is heated to a temperature below that ofincandescence and, in general, the properties noted are a resultof crystal imperfections. All crystals have defects, which may bedue to a vacancy at one of the lattice points, an impurity atom ata lattice point or an interstitial atom or ion in the lattice structure.Regardless of type, the presence of imperfections will introducenew energy levels into normal lattice energy bands. It is possiblethat some of the energy levels will constitute metastable statesand be able to trap electrons or holes for extended periods.Excitation can also be stored in some metastable excitedcharge-transfer states which will appear when an impurity iondemonstrates a well-pronounced covalent bond with the ligand.The mechanism of excitation energy transformation into outputlight is one of the most crucial points in luminescent materialdesign. Both the threshold of the radiation dose detection andaccuracy measurements depend on the efficiency of energytransformation in TL Dosimetry (1). Measurement of the radiationdose has become a science of ever-increasing importance inestimating the risk and benefits inherent in the use of andexposure to ionizing radiation.TL in alkali halides has been studied for more than 60years. Itis known that emission is due to radiative recombination ofhalogen atoms thermallyreleasedfromtheinterstitialpositionswith F centres (2). Irradiated alkali halides have been used inmost experiments, and while analysing the Thermoluminescencedata it has most often been assumed that irradiation has createdan equal number of recombination centres andfilled traps (2).Colour centres in alkali halides have been studied for manyyears. It is known that the electrolytic colouration produced inpotassium halides is lost within a day (3). Colour centres havemostly been studied in single crystals, whereas applicationssuch as Dosimetry of ionizing radiation using TL more ofteninvolve measurements on powders. It is generally believed thatthe mechanism of colour centre production is similar for singlecrystals and microcrystalline powders. Production of colour centresby g-irradiation in NaCl, KCl and KBr is reported by Deshmukhand co-workers. (4 –7) in crystals and microcrystalline powder. Onthe development of TL Dosimetry materials, work has concentratedon enhancement in TL intensity.Recently, Bangaru and co-workers (8,9) also reported enhancedluminescent properties and TL studies in alkali halides by dopingrare earth materials. Bhujbal et al. (10) also observed increasedluminescence(i.e.Lyoluminescence(LL),TLandMechanolumines-cence (ML)) intensity in NaCl doped with rare earth material (10).Many alkali halide-based materials like LiF exhibit importantdosimetric properties. The study of luminescence properties in alkalihalidesto findapossibledosimetric material is a challenging taskin the development of radiation Dosimetry.In this article, the TL of g-irradiated KCl (pure) and KCl:Dy(0.05–0.5mol%) are studied for possible dosimetric materials inorder to develop a high dose in ionizing radiation Dosimetry.

  • Phosphors MMgAl10O17: Eu,Dy (M=Ba,Sr,Ca) irradiated by Cs137 for Thermoluminescence Dosimetry
    Indian Journal of Pure & Applied Physics, 2008
    Co-Authors: S.j. Dhoble, G. V. Bramhe, R. G. Sonkawade, S.v. Moharil
    Abstract:

    The Thermoluminescence (TL) of Eu, Dy activated M MgAl 10 O 17 [M=Ba,Sr,Ca] phosphors has been reported in this paper. These phosphors are prepared by combustion synthesis. TL glow intensity of these phosphors is higher as compared to conventional CaSO 4 :Dy TL-phosphor. M MgAl 10 O 17 [M=Ba,Sr,Ca] phosphors may be the possible candidate for Thermoluminescence Dosimetry of ionizing radiations.

  • Correlated ESR, PL and TL studies on Sr5(PO4)3Cl:Eu Thermoluminescence Dosimetry phosphor
    Journal of Luminescence, 2007
    Co-Authors: S.j. Dhoble, S.v. Moharil, T.k. Gundu Rao
    Abstract:

    Electron spin resonance (ESR), Thermoluminescence and photoluminescence studies in Eu2+ activated Sr-5(PO4)(3)Cl phosphor are reported in this paper. The Sr-5(PO4)(3)Cl:Eu2+ phosphor is twice as sensitive as the conventional CaSO4:Dy phosphor used in Thermoluminescence Dosimetry of ionizing radiations. It has a linear response, simple glow curve, emission peaking at 456 nm. The defect centers formed in the Sr-5(PO4)(3)Cl:Eu2+ phosphor are studied by using the technique of ESR. A dominant TL glow peak at 430 K with a smaller shoulder at 410K is observed in the phosphor. ESR studies indicate the presence at three centers at room temperature. Step annealing measurements show a connection between one of the centers and the dominant glow peak at 430 K. The 430 K TL peak is well correlated with center I, which is tentatively identified as (PO4)(2-) radical. (c) 200

  • Preparation and characterization of the Sr5(PO4)3Cl:Eu2+ phosphor
    Journal of Physics D: Applied Physics, 1999
    Co-Authors: S.j. Dhoble
    Abstract:

    A phosphor Sr5 (PO4 )3 Cl, doped with Eu2+ is reported. This is shown to be at least twice as sensitive as the conventional CaSO4 :Dy phosphor used in Thermoluminescence Dosimetry of ionizing radiations. It has a linear response, simple glow curve, emission peaking at 456 nm, negligible fading and excellent reusability. Characterization of the phosphor using x-ray diffraction, photoluminescence and Thermoluminescence techniques is described.

  • Preparation and Characterization of the K3Na(SO4)2: Eu Phosphor
    Physica Status Solidi (a), 1993
    Co-Authors: S.j. Dhoble, S.v. Moharil, S.m. Dhopte, P.l. Muthal, V. K. Kondawar
    Abstract:

    A new phosphor in the system K2SO4 Na2SO4 doped with Eu is reported. This is shown to be at least thrice as sensitive as the conventional CaSO4: Dy phosphor used in the Thermoluminescence Dosimetry of ionizing radiations. Characterization of this phosphor using XRD, PL, and TL techniques is described.

Dimos Baltas - One of the best experts on this subject based on the ideXlab platform.

  • Monte Carlo and Thermoluminescence Dosimetry of the new model I25.S17 interstitial brachytherapy seed
    Medical physics, 2005
    Co-Authors: G. Lymperopoulou, Panagiotis Papagiannis, Loukas Sakelliou, Pantelis Karaiskos, Panagiotis Sandilos, A. Przykutta, Dimos Baltas
    Abstract:

    Monte Carlo simulation and experimental Thermoluminescence Dosimetry were utilized for the dosimetric characterization of the new IsoSeed registered model I25.S17 {sup 125}I interstitial brachytherapy seed. The new seed design is similar to that of the selectSeed and 6711 seeds, with the exception of its molybdenum marker. Full dosimetric data are presented following the recommendations in the Update of the AAPM Task Group 43 report (TG-43U1). A difference of 3.3% was found between Monte Carlo dose rate constant results calculated by air kerma strengths from simulations using a point detector and a detector resembling the solid angle subtended to the seed by the Wide Angle Free Air Chamber (WAFAC) in the primary standard calibration geometry. Following the TG-43U1 recommendations, an average value of {lambda}{sub MC}=(0.929{+-}0.014) cGy h{sup -1} U{sup -1} was adopted for the new seed. This value was then averaged with the measured value of {lambda}{sub EXP}=(0.951{+-}0.044) cGy h{sup -1} U{sup -1} to yield the proposed dose rate constant for the new seed that is equal to {lambda}=(0.940{+-}0.051) cGy h{sup -1} U{sup -1}. The Monte Carlo calculated radial dose function and two-dimensional (2-D) anisotropy function results for the new seed were found in agreement with experimental results to within statisticalmore » uncertainty of repeated measurements. Monte Carlo simulations were also performed for {sup 125}I seeds of similar geometry and dimensions for the purpose of comparison. The new seed presents dosimetric characteristics that are very similar to that of the selectSeed. In comparison to the most extensively studied Amersham 6711 seed, the new one presents similar dosimetric characteristics with a slightly reduced dose rate constant (1.5%)« less

  • in vivo Thermoluminescence Dosimetry dose verification of transperineal 192ir high dose rate brachytherapy using ct based planning for the treatment of prostate cancer
    International Journal of Radiation Oncology Biology Physics, 2003
    Co-Authors: G Anagnostopoulos, Dimos Baltas, A Geretschlaeger, Thomas Martin, P Papagiannis, Nikolaos Tselis, Nikolaos Zamboglou
    Abstract:

    Abstract Purpose To evaluate the potential of in vivo Thermoluminescence Dosimetry to estimate the accuracy of dose delivery in conformal high-dose-rate brachytherapy of prostate cancer. Methods and materials A total of 50 LiF, TLD-100 cylindrical rods were calibrated in the dose range of interest and used as a batch for all fractions. Fourteen dosimeters for every treatment fraction were loaded in a plastic 4F catheter that was fixed in either one of the 6F needles implanted for treatment purposes or in an extra needle implanted after consulting with the patient. The 6F needles were placed either close to the urethra or in the vicinity of the median posterior wall of the prostate. Initial results are presented for 18 treatment fractions in 5 patients and compared to corresponding data calculated using the commercial treatment planning system used for the planning of the treatments based on CT images acquired postimplantation. Results The maximum observed mean difference between planned and delivered dose within a single treatment fraction was 8.57% ± 2.61% (root mean square [RMS] errors from 4.03% to 9.73%). Corresponding values obtained after averaging results over all fractions of a patient were 6.88% ± 4.93% (RMS errors from 4.82% to 7.32%). Experimental results of each fraction corresponding to the same patient point were found to agree within experimental uncertainties. Conclusions Experimental results indicate that the proposed method is feasible for dose verification purposes and suggest that dose delivery in transperineal high-dose-rate brachytherapy after CT-based planning can be of acceptable accuracy.

T.k. Gundu Rao - One of the best experts on this subject based on the ideXlab platform.

  • Correlated ESR, PL and TL studies on Sr5(PO4)3Cl:Eu Thermoluminescence Dosimetry phosphor
    Journal of Luminescence, 2007
    Co-Authors: S.j. Dhoble, S.v. Moharil, T.k. Gundu Rao
    Abstract:

    Electron spin resonance (ESR), Thermoluminescence and photoluminescence studies in Eu2+ activated Sr-5(PO4)(3)Cl phosphor are reported in this paper. The Sr-5(PO4)(3)Cl:Eu2+ phosphor is twice as sensitive as the conventional CaSO4:Dy phosphor used in Thermoluminescence Dosimetry of ionizing radiations. It has a linear response, simple glow curve, emission peaking at 456 nm. The defect centers formed in the Sr-5(PO4)(3)Cl:Eu2+ phosphor are studied by using the technique of ESR. A dominant TL glow peak at 430 K with a smaller shoulder at 410K is observed in the phosphor. ESR studies indicate the presence at three centers at room temperature. Step annealing measurements show a connection between one of the centers and the dominant glow peak at 430 K. The 430 K TL peak is well correlated with center I, which is tentatively identified as (PO4)(2-) radical. (c) 200

Nikolaos Zamboglou - One of the best experts on this subject based on the ideXlab platform.

  • in vivo Thermoluminescence Dosimetry dose verification of transperineal 192ir high dose rate brachytherapy using ct based planning for the treatment of prostate cancer
    International Journal of Radiation Oncology Biology Physics, 2003
    Co-Authors: G Anagnostopoulos, Dimos Baltas, A Geretschlaeger, Thomas Martin, P Papagiannis, Nikolaos Tselis, Nikolaos Zamboglou
    Abstract:

    Abstract Purpose To evaluate the potential of in vivo Thermoluminescence Dosimetry to estimate the accuracy of dose delivery in conformal high-dose-rate brachytherapy of prostate cancer. Methods and materials A total of 50 LiF, TLD-100 cylindrical rods were calibrated in the dose range of interest and used as a batch for all fractions. Fourteen dosimeters for every treatment fraction were loaded in a plastic 4F catheter that was fixed in either one of the 6F needles implanted for treatment purposes or in an extra needle implanted after consulting with the patient. The 6F needles were placed either close to the urethra or in the vicinity of the median posterior wall of the prostate. Initial results are presented for 18 treatment fractions in 5 patients and compared to corresponding data calculated using the commercial treatment planning system used for the planning of the treatments based on CT images acquired postimplantation. Results The maximum observed mean difference between planned and delivered dose within a single treatment fraction was 8.57% ± 2.61% (root mean square [RMS] errors from 4.03% to 9.73%). Corresponding values obtained after averaging results over all fractions of a patient were 6.88% ± 4.93% (RMS errors from 4.82% to 7.32%). Experimental results of each fraction corresponding to the same patient point were found to agree within experimental uncertainties. Conclusions Experimental results indicate that the proposed method is feasible for dose verification purposes and suggest that dose delivery in transperineal high-dose-rate brachytherapy after CT-based planning can be of acceptable accuracy.

Tomas Kron - One of the best experts on this subject based on the ideXlab platform.

  • Thermoluminescence Dosimetry (TLD) IN MEDICINE: FIVE 'W'S AND ONE HOW.
    Radiation protection dosimetry, 2020
    Co-Authors: Tomas Kron, Peta Lonski, Eduardo G. Yukihara
    Abstract:

    Thermoluminescence Dosimetry (TLD) has a long history of applications in medicine. However, despite its versatility and sensitivity its use is anecdotally diminishing, at least in part due to the complexity and work intensity of a quality TLD service. The present paper explores the role of TLD in medicine using a common inquiry methodology (5W1H) which systematically asks 'Who, What, When, Where, Why and How' to identify what role TLD could and should play in medical applications.

  • Thermoluminescence Dosimetry for skin dose assessment during intraoperative radiotherapy for early breast cancer
    Australasian Physical & Engineering Sciences in Medicine, 2010
    Co-Authors: P Fogg, Tomas Kron, Boon Chua, J Hagekyriakou
    Abstract:

    Dosimetry for intraoperative radiotherapy (IORT) after wide local excision for breast cancer using a 50 kV X-ray needle (Intrabeam) was performed in vivo using Thermoluminescence Dosimetry. Eight LiF:Mg,Ti chips were placed on the skin around the incision site after wide local excision while the tumour bed was irradiated to a prescribed dose of 5 Gy 10 mm from the applicator surface. The maximum and mean measured skin dose for 57 patients ranged from 0.64 to 7.1 Gy and 0.56 to 4.78 Gy, respectively, reflecting different tissue thicknesses overlying the applicator. The average maximum dose of 2.93 ± 1.46 Gy was below the threshold for severe radiation skin toxicity.

  • Applications of Thermoluminescence Dosimetry in Medicine
    Radiation Protection Dosimetry, 1999
    Co-Authors: Tomas Kron
    Abstract:

    Thermoluminescence Dosimetry (TLD) features many advantages such as small detector size and close tissue equivalence that make it useful for a variety of applications in medicine. In medical imaging the high sensitivity of TLD materials such as LiF:Mg,Cu.P and Al 2 O 3 :C enables risk assessment even for low dose procedures. In radiotherapy, the fact that no cables are required during the measurement allows the use of TLDs inside tissue-equivalent phantoms to verify radiation doses delivered in new treatment techniques. These features make TLD also the most versatile in vivo Dosimetry tool allowing dose assessments directly on patients during diagnostic or therapeutic procedures. In addition to these clinical uses, TLD is widely employed for quality assurance in medicine. Dosimetric intercomparisons between different centres and spot checks of dose delivered in diagnostic procedures have found their way into many national and intemational guidelines for best practice.

  • Thermoluminescence Dosimetry and its applications in medicine--Part 2: History and applications.
    Australasian physical & engineering sciences in medicine, 1995
    Co-Authors: Tomas Kron
    Abstract:

    Thermoluminescence Dosimetry (TLD) has been available for Dosimetry of ionising radiation for nearly 100 years. The variety of materials and their different physical forms allow the determination of different radiation qualities over a wide range of absorbed dose. This makes TL dosimeters useful in radiation protection where dose levels of microGy are monitored as well as in radiotherapy where doses up to several Gray are to be measured. The major advantages of TL detectors are their small physical size and that no cables or auxiliary equipment is required during the dose assessment. Therefore TLD is a good method for point dose measurements in phantoms as well as for in vivo Dosimetry on patients during radiotherapy treatment. As an integrative dosimetric technique, it can be applied to personal Dosimetry and it lends itself to the determination of dose distributions due to multiple or moving radiation sources (e.g. conformal and dynamic radiotherapy, computed tomography). In addition, TL dosimeters are easy to transport, and they can be mailed. This makes them well suited for intercomparison of doses delivered in different institutions. The present article aims at describing the various applications TLD has found in medicine by taking into consideration the physics and practice of TLD measurements which have been discussed in the first part of this review (Australas. Phys. Eng. Sci. Med. 17: 175-199, 1994).

  • Thermoluminescence Dosimetry and its applications in medicine--Part 1: Physics, materials and equipment.
    Australasian physical & engineering sciences in medicine, 1994
    Co-Authors: Tomas Kron
    Abstract:

    Thermoluminescence Dosimetry (TLD) is a versatile tool for the assessment of dose from ionising radiation. The wide variety of TLD materials and their different physical forms allow the determination of different radiation qualities at dose levels from microGy to kGy. Major advantages of TL dosimeters are their small physical size and that no cables or auxiliary equipment is required during the dose measurement. This makes them well suited for a wide range of applications in medicine. However, while larger institutions with extensive experience in TLD commonly achieve quite good results, Thermoluminescence Dosimetry appears a bit like a black art for physicists who attempt to set up a TLD system for the first time. Therefore, the present article aims at summarising the relevant literature describing problems and possible pitfalls in the evaluation of TLD readings. The second part of the review (to be published) will discuss typical applications of TLD in medicine. Most applications and the major part of the literature are based on lithium fluoride doped with magnesium and titanium (LiF:Mg,Ti). However, other materials such as CaSO4:Dy are widely used, and some more recent TL materials such as LiF:Mg,Cu,P show great potential for radiation Dosimetry. Therefore, the present article while focusing on LiF:Mg,Ti also includes other TLD materials of interest for Dosimetry in the medical field. Furthermore, TLD apparatus and a variety of TLD applications and techniques shall be discussed with two intentions: firstly to give an update of TLD in medicine, and secondly to enable readers to set up or optimise their own TLD system.