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S.w.s. Mckeever - One of the best experts on this subject based on the ideXlab platform.

  • Optically Stimulated Luminescence: A brief overview
    Radiation Measurements, 2011
    Co-Authors: S.w.s. Mckeever
    Abstract:

    The use of Optically Stimulated Luminescence (OSL) in radiation dosimetry has been conditioned by the availability of suitable dosimetry (OSLD) materials. The crucial property dictating the suitability of a material as an OSLD is the material’s defect structure. This paper reviews some of the recent developments in radiation dosimetry that have been enabled by knowledge of the charge trapping and recombination processes occurring in OSLD materials during irradiation and stimulation. Although many materials have been and are currently being studied, this short review focuses on just two, namely carbon-doped aluminum oxide (Al2O3:C) and europium-doped potassium bromide (KBr:Eu). The defect structure and trapping/recombination mechanisms in these materials have led to application in several areas of radiation dosimetry and dose imaging. Two recent areas of development are in space dosimetry (for Al2O3:C) and in medical dosimetry (for KBr:Eu). This overview briefly describes these latter modern applications and relates the functionality of the OSLDs to their basic defect properties.

  • Optically Stimulated Luminescence (OSL) dosimetry in medicine
    Physics in medicine and biology, 2008
    Co-Authors: Eduardo G. Yukihara, S.w.s. Mckeever
    Abstract:

    This paper reviews fundamental and practical aspects of Optically Stimulated Luminescence (OSL) dosimetry pertaining to applications in medicine, having particularly in mind new researchers and medical physicists interested in gaining familiarity with the field. A basic phenomenological model for OSL is presented and the key processes affecting the outcome of an OSL measurement are discussed. Practical aspects discussed include stimulation modalities (continuous-wave OSL, pulsed OSL and linear modulation OSL), basic experimental setup, available OSL readers, optical fiber systems and basic properties of available OSL dosimeters. Finally, results from the recent literature on applications of OSL in radiotherapy, radiodiagnostics and heavy charged particle dosimetry are discussed in light of the theoretical and practical framework presented in this review. Open questions and future challenges in OSL dosimetry are highlighted as a guide to the research needed to further advance the field.

  • Optically Stimulated Luminescence and its use in medical dosimetry
    Radiation Measurements, 2006
    Co-Authors: Mark S. Akselrod, L Botterjensen, S.w.s. Mckeever
    Abstract:

    Abstract The Optically Stimulated Luminescence (OSL) technique has already became a successful tool in personal radiation dosimetry, geological and archeological dating, and in radiation diagnostic imaging. This review briefly describes the history of OSL. Significant advances have been made recently in the theoretical study of OSL to explain the behavior of radiation sensitive materials with several types of dosimetry traps, recombination centers and competing deep traps. Progress in material and detector engineering has allowed new and promising developments regarding OSL applications in the medical field. Special attention is dedicated to Al 2 O 3 :C as a material of choice for many dosimetric applications; present technology can provide Al 2 O 3 :C fiber sensors with diameters as small as 300 μ m . A new RL/OSL fiberoptic system has a high potential for in vivo and in vitro dosimetry in both radiation therapy and diagnostic mammography. Different aspects of instrumentation, data processing algorithms, post-irradiation and real-time measurements are described.

  • Optically Stimulated Luminescence Dosimetry - Chapter 2 – Optically Stimulated Luminescence theory
    Optically Stimulated Luminescence Dosimetry, 2003
    Co-Authors: L. Bøtter-jensen, S.w.s. Mckeever, A.g. Wintle
    Abstract:

    This chapter explains the Optically Stimulated Luminescence theory. In Optically Stimulated Luminescence (OSL) the stimulating energy source is light (UV, visible or infrared). This general description of OSL places the phenomenon within the family of Stimulated relaxation phenomena (SRP). For the specific case of OSL, the intensity of the emitted Luminescence is related to the rate at which the system returns to equilibrium. The rate at which the equilibrium is re-established is a function of the concentration of trapped (metastable) charge and in the simplest (first-order) case the rate is linearly proportional to the trapped charge concentration. The integral of the Luminescence-versus-time curve is thus related to the trapped charge concentration, which, in turn, is proportional (in the ideal case) to the initial dose of the absorbed radiation. This is the basis for the use of OSL in radiation dosimetry. In other SRP, the form of perturbation differs along with the property being monitored during the stimulation. The chapter further provides generalized mathematical description of OSL.

  • Optically Stimulated Luminescence Dosimetry - Chapter 4 – Passive Optically Stimulated Luminescence dosimetry
    Optically Stimulated Luminescence Dosimetry, 2003
    Co-Authors: L. Bøtter-jensen, S.w.s. Mckeever, A.g. Wintle
    Abstract:

    This chapter provides an overview of passive Optically Stimulated Luminescence (OSL) dosimetry. The key features of OSL that make it so attractive for personal dosimetry include the ability to tune the performance across a wide dynamic dose range by being able to vary the stimulation power. This allows optimum sensitivity at both the low-dose and the high-dose ends of the dose response. Furthermore, by adjusting the stimulation power appropriate to the dose range, one has the ability to re-read the OSL signal since the high sensitivity allows dose assessment even though only a fraction of the stored charge is depleted during the measurement. Thus, a complete re-analysis is achieved and true, independent dose readings are possible. This is to be distinguished from film badge dosimetry in which the developed image can be read second time, but the film can only be developed once; thus the dose readings are not independent in this sense. The chapter further explains environmental OSL dosimetry using Al 2 0 3 :C.

Eduardo G. Yukihara - One of the best experts on this subject based on the ideXlab platform.

  • Applications of Optically Stimulated Luminescence in Medical Dosimetry.
    Radiation protection dosimetry, 2021
    Co-Authors: Eduardo G. Yukihara, Tomas Kron
    Abstract:

    If the first decade of the new millennium saw the establishment of a more solid foundation for the use of the Optically Stimulated Luminescence (OSL) in medical dosimetry, the second decade saw the technique take root and become more widely used in clinical studies. Recent publications report not only characterization and feasibility studies of the OSL technique for various applications in radiotherapy and radiology, but also the practical use of OSL for postal audits, estimation of staff dose, in vivo dosimetry, dose verification and dose mapping studies. This review complements previous review papers and reports on the topic, providing a panorama of the new advances and applications in the last decade. Attention is also dedicated to potential future applications, such as LET dosimetry, 2D/3D dosimetry using OSL, dosimetry in magnetic resonance imaging-guided radiotherapy (MRIgRT) and dosimetry of extremely high dose rates (FLASH therapy).

  • beo Optically Stimulated Luminescence dosimetry using automated research readers
    Radiation Measurements, 2016
    Co-Authors: Eduardo G. Yukihara, Adriano B Andrade, S Eller
    Abstract:

    Abstract The objective of this work is to develop a methodology for precise Optically Stimulated Luminescence (OSL) dosimetry using BeO chips and an automated research reader (Riso TL/OSL reader, Riso National Laboratory), documenting optimum detector preparation procedures, readout conditions, sensitivity, minimum detectable dose, and precision. We investigated the influence of stimulation wavelengths (green versus blue LEDs), pre-irradiation annealing conditions, reproducibility, sensitivity changes with dose or annealing, and precisions in the dose response curve with a reference irradiation. The results demonstrate that with proper annealing (700 °C/15 min) and the readout procedure described here (blue stimulation, total OSL area as the signal, and a fixed dose to correct for detector sensitivity, among other factors), a precision

  • Investigations of MgO:Li,Gd thermally and Optically Stimulated Luminescence
    Journal of Luminescence, 2013
    Co-Authors: L.c. Oliveira, B.a. Doull, Eduardo G. Yukihara
    Abstract:

    Abstract The purpose of this work is to investigate the thermoLuminescence (TL) and Optically Stimulated Luminescence (OSL) properties of MgO:Li,Gd synthesized by solution combustion synthesis as a function of different synthesis parameters. In addition to TL and OSL, characterization techniques include x-ray diffraction (XRD) and radioLuminescence (RL). We also investigated undoped and singly-doped samples for comparison. We show that MgO:Li,Gd may serve as the basis for a new OSL material with intensity comparable to commercial Al2O3:C and narrow emission at 315 nm associated with Gd3+. Li co-doping has increased the OSL signal by several orders of magnitude when compared to MgO undoped or MgO:Gd. However, elimination of shallow trapping centers (associated with TL peaks

  • Influence of shallow traps on time-resolved Optically Stimulated Luminescence measurements of Al2O3:C,Mg
    Journal of Applied Physics, 2011
    Co-Authors: Grégoire Denis, Mark S. Akselrod, Eduardo G. Yukihara
    Abstract:

    The objective of this paper is to investigate the influence of shallow traps on the signals from Al2O3:C,Mg obtained using time-resolved Optically Stimulated Luminescence (TR-OSL) measurements through experiments and numerical simulations. TR-OSL measurements of Al2O3:C,Mg were carried out and the resulting Optically Stimulated Luminescence (OSL) curves were investigated as a function of the temperature. The numerical simulations were carried out using the rate-equations for a simplified model of Al2O3:C,Mg containing two types of Luminescence centers with different Luminescence lifetimes and three types of electron traps (a shallow trap, a main dosimetric trap, and a thermally disconnected deep trap). Both experimental results and simulations show that the OSL signals during and between the stimulation pulses are affected by the presence of shallow traps. However, with an appropriate choice of timing parameters, the influence of shallow traps can be reduced by calculating the difference between the signa...

  • Optically Stimulated Luminescence (OSL) dosimetry in medicine
    Physics in medicine and biology, 2008
    Co-Authors: Eduardo G. Yukihara, S.w.s. Mckeever
    Abstract:

    This paper reviews fundamental and practical aspects of Optically Stimulated Luminescence (OSL) dosimetry pertaining to applications in medicine, having particularly in mind new researchers and medical physicists interested in gaining familiarity with the field. A basic phenomenological model for OSL is presented and the key processes affecting the outcome of an OSL measurement are discussed. Practical aspects discussed include stimulation modalities (continuous-wave OSL, pulsed OSL and linear modulation OSL), basic experimental setup, available OSL readers, optical fiber systems and basic properties of available OSL dosimeters. Finally, results from the recent literature on applications of OSL in radiotherapy, radiodiagnostics and heavy charged particle dosimetry are discussed in light of the theoretical and practical framework presented in this review. Open questions and future challenges in OSL dosimetry are highlighted as a guide to the research needed to further advance the field.

M.l. Chithambo - One of the best experts on this subject based on the ideXlab platform.

M.l. Chithambo - One of the best experts on this subject based on the ideXlab platform.

  • Thermal assistance in the Optically Stimulated Luminescence of superluminous Sr4Al14O25: Eu2+,Dy3+
    Physica B: Condensed Matter, 2021
    Co-Authors: M.l. Chithambo
    Abstract:

    Abstract The thermally induced increase in Optically Stimulated Luminescence of super-luminous Sr4Al14O25:Eu,Dy is reported. To isolate this thermal assistance to emission, which is otherwise obscured by high intensity transient emissions, stimulation was done using 870 nm infrared light. The Optically Stimulated Luminescence intensity measured between 20 and 200 °C goes through a peak. The profile is reproducible and is independent of whether the measurements are made with the temperature increasing or decreasing. The initial increase in signal is ascribed to thermal assistance and the subsequent decrease is due to thermal quenching. The activation energy of thermal assistance was determined as 0.30 ± 0.01 eV. The corresponding value for the activation energy for thermal quenching is also reported as are methods for determining these parameters from the temperature dependence of the Luminescence. The thermal assistance effect is explained with reference to a configurational coordinate model.

  • Optically Stimulated Luminescence of cowrie shells.
    Applied radiation and isotopes : including data instrumentation and methods for use in agriculture industry and medicine, 2020
    Co-Authors: F.o. Ogundare, M.l. Chithambo, B.o. Akintunde
    Abstract:

    Abstract Characteristics of continuous wave Optically Stimulated Luminescence (CW-OSL) and linear modulation OSL (LM-OSL) from three different types of cowrie shells are presented. Irradiated samples were Optically Stimulated at 72 mW/cm2 for CW-OSL and linearly ramped from zero to 72 mW/cm2 to obtain LM-OSL. The measured CW-OSL and LM-OSL curves of the shells are each determined to consist of three components namely fast, medium and slow components. The fast, medium and slow LM-OSL components peak at 17.0 ± 0.8, 45.0 ± 1.8 and 140.8 ± 6.7 s respectively for all samples. In addition, peak positions are independent of dose. The photoionization cross-sections of the OSL traps for the three components estimated from CW-OSL are similar to those determined using LM-OSL. The OSL of the three components increases linearly with dose. The coefficient of variation of responses from repeated measurements of same aliquot lies below 2.3%. The shells are thus potential materials for retrospective dosimetry.

  • A time-correlated photon counting system for measurement of pulsed Optically Stimulated Luminescence
    Journal of Luminescence, 2011
    Co-Authors: M.l. Chithambo
    Abstract:

    Abstract A versatile light-emitting-diode system for measurement of time-resolved Luminescence spectra is described. The instrument is an improvement on a previously reported version [1] also based on pulsed light-emitting diodes. The present configuration offers substantially improved performance in measurement of time-resolved Optically Stimulated Luminescence spectra and records the Luminescence with better dynamic throughput. Measurements made on sedimentary quartz annealed at 800 °C as an exemplar show that the Luminescence obtained after the light pulse as a proportion of the total measured signal falls within the usable dynamic range of 0.1–98% for pulse-widths between 3 and 198 μ s , a range of pulse-widths and so Luminescence yield that is sufficient for most contemporary applications of time-resolved Optically Stimulated Luminescence.

L. Bøtter-jensen - One of the best experts on this subject based on the ideXlab platform.

  • Optically Stimulated Luminescence Dosimetry - Chapter 2 – Optically Stimulated Luminescence theory
    Optically Stimulated Luminescence Dosimetry, 2003
    Co-Authors: L. Bøtter-jensen, S.w.s. Mckeever, A.g. Wintle
    Abstract:

    This chapter explains the Optically Stimulated Luminescence theory. In Optically Stimulated Luminescence (OSL) the stimulating energy source is light (UV, visible or infrared). This general description of OSL places the phenomenon within the family of Stimulated relaxation phenomena (SRP). For the specific case of OSL, the intensity of the emitted Luminescence is related to the rate at which the system returns to equilibrium. The rate at which the equilibrium is re-established is a function of the concentration of trapped (metastable) charge and in the simplest (first-order) case the rate is linearly proportional to the trapped charge concentration. The integral of the Luminescence-versus-time curve is thus related to the trapped charge concentration, which, in turn, is proportional (in the ideal case) to the initial dose of the absorbed radiation. This is the basis for the use of OSL in radiation dosimetry. In other SRP, the form of perturbation differs along with the property being monitored during the stimulation. The chapter further provides generalized mathematical description of OSL.

  • Optically Stimulated Luminescence Dosimetry - Chapter 4 – Passive Optically Stimulated Luminescence dosimetry
    Optically Stimulated Luminescence Dosimetry, 2003
    Co-Authors: L. Bøtter-jensen, S.w.s. Mckeever, A.g. Wintle
    Abstract:

    This chapter provides an overview of passive Optically Stimulated Luminescence (OSL) dosimetry. The key features of OSL that make it so attractive for personal dosimetry include the ability to tune the performance across a wide dynamic dose range by being able to vary the stimulation power. This allows optimum sensitivity at both the low-dose and the high-dose ends of the dose response. Furthermore, by adjusting the stimulation power appropriate to the dose range, one has the ability to re-read the OSL signal since the high sensitivity allows dose assessment even though only a fraction of the stored charge is depleted during the measurement. Thus, a complete re-analysis is achieved and true, independent dose readings are possible. This is to be distinguished from film badge dosimetry in which the developed image can be read second time, but the film can only be developed once; thus the dose readings are not independent in this sense. The chapter further explains environmental OSL dosimetry using Al 2 0 3 :C.

  • Optically Stimulated Luminescence in Retrospective Dosimetry
    Radiation Protection Dosimetry, 2002
    Co-Authors: L. Bøtter-jensen, Andrew S. Murray
    Abstract:

    Since the beginning of the 1990s the exploration of Optically Stimulated Luminescence (OSL) in retrospective accident dosimetry has driven an intensive investigation and development programme at Rise into measurement facilities and techniques. This paper reviews some of the outcomes of this programme, including the evaluation of the single-aliquot regenerative-dose (SAR) measurement protocol with brick quartz and the determination of dose-depth profiles in building materials as a guide to determining the mean energy of the incident radiation. Investigations into heated materials are most advanced, and a lower detection limit for quartz extracted from Chernobyl bricks was determined to be

  • Optically Stimulated Luminescence in retrospective dosimetry.
    Radiation protection dosimetry, 2002
    Co-Authors: L. Bøtter-jensen, Andrew S. Murray
    Abstract:

    Since the beginning of the 1990s the exploration of Optically Stimulated Luminescence (OSL) in retrospective accident dosimetry has driven an intensive investigation and development programme at Risø into measurement facilities and techniques. This paper reviews some of the outcomes of this programme, including the evaluation of the single-aliquot regenerative-dose (SAR) measurement protocol with brick quartz and the determination of dose-depth profiles in building materials as a guide to determining the mean energy of the incident radiation. Investigations into heated materials are most advanced, and a lower detection limit for quartz extracted from Chernobyl bricks was determined to be

  • Optically Stimulated Luminescence techniques in retrospective dosimetry
    Radiation Physics and Chemistry, 2001
    Co-Authors: L. Bøtter-jensen, Andrew S. Murray
    Abstract:

    Abstract Optically Stimulated Luminescence signals from natural quartz and feldspar are now used routinely in dating geological and archaeological materials. More recently they have also been employed in accident dosimetry, i.e. the retrospective assessment of doses received as a result of a nuclear accident. Since 1990 the exploration of this wide variety of applications has driven an intensive investigation and development programme at Riso, in measurement facilities and techniques. This paper reviews some of the outcomes of this programme, including (i) optimisation of stimulation and emission windows, and detection sensitivity, (ii) experience with various stimulation light sources, including filtered incandescent lamps (420–550 nm) and high intensity light emitting diodes (470 nm) and laser diodes (830–850 nm). We also discuss recently developed high-precision single-aliquot measurement protocols. These offer exciting possibilities in dating and accident dosimetry, and are already leading to new demands on measurement techniques and facilities.