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Observation of strong thermally transferred optically stimulated luminescence (TT-OSL) in BeO
摘要： This work reports the observation of strong thermally transferred optically stimulated luminescence (TT-OSL) signal of BeO OSL ceramic detectors. If the detector is irradiated and the OSL signal is measured for a prolonged time (bleached), subsequent OSL measurements result in zero signal. If the same detector, however, is heated to temperatures in the 225 – 335 °C range (at 5 °C/s), subsequent OSL measurements at room temperature result in an intense signal, even without additional irradiation. The TT-OSL is maximum for a pre-heating to 275 °C (if heated linearly at 5 °C/s), reaching a value of 56 % of the original OSL signal. Both OSL and TT-OSL are reproducible (~3 % standard deviation) and linear with dose over the dose range investigated (up to 100 mGy). The shape of the OSL and TT-OSL curves are essentially identical. A possible explanation for this phenomenon is the thermally stimulated transfer of trapped charges from optically inactive traps to optically active traps responsible for the OSL signal. Correlation between the OSL, TT-OSL and the thermoluminescence (TL) peaks suggests the trapping centers associated with the TL peak at ~310 °C/s (at 5 °C/s) as the source of the trapped charges. These results have implication for the re-estimation of the OSL signal in BeO detectors accidentally exposed to light. Not only they provide further evidence that the material is not completely reset simply by bleaching (optical stimulation), but open a new line of investigation into the underlying TL/OSL mechanisms in BeO.
关键词： thermoluminescence,optically stimulated luminescence,BeO,thermally transferred optically stimulated luminescence,luminescence dosimetry,recuperation
更新于2025-09-23 15:23:52
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Development of a 2D dosimeter using the optically stimulated luminescence of NaMgF3:Eu with CCD camera readout
摘要： A two-dimensional (2D) dosimeter has been developed using tissue-equivalent NaMgF3:Eu as a radiation-sensing material. The bulk compound shows optically stimulated luminescence (OSL) after irradiation in the form of 359 nm Eu2+ emission and where the OSL stimulation occurs at wavelengths above 400 nm. The OSL integrated intensity is shown to be linear up to at least 100 Gy when stimulated with 445 nm light. When the OSL is detected using a thermoelectrically cooled CCD camera, 2D X-ray images can be obtained and the measured intensity is proportional to the total radiation dose. NaMgF3:Eu can be incorporated into epoxy to produce imaging films and both the bulk compound and a film are characterised using the 2D setup. The noise equivalent dose in 2D for the film is determined to be 14 mGy. The modulation transfer function (MTF) is determined and the spatial resolution at MTF = 0.2 is 2.9 lp/mm for the bulk material and 1.25 lp/mm for the film. Our results show that NaMgF3:Eu has potential in the field of 2D dosimetry, where the response to radiation is linear to high doses, sensitive to low doses, and doses can be resolved with a spatial resolution below 1 mm.
关键词： fluoroperovskite,optically stimulated luminescence,dosimetry,NaMgF3
更新于2025-09-23 15:23:52
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Changes of Optically Stimulated Luminescence Dosimeter Sensitivity with High Dose
摘要： We investigated the effect of high dose on the sensitivity of optically stimulated luminance dosimeters (OSLDs) on Co-60 gamma rays and used a commercial OLSD (Landauer, Inc., Glenwood, IL). New OSLDs were chosen arbitrarily and were irradiated with 1 Gy repeatedly. We confirmed the change in the radiation sensitivity after repeated irradiation. The OSLD sensitivity increased up to 3% after irradiating for seven times and decreased continuously after the eighth time. It dropped by approximately 0.35 Gy per irradiation. Finally, after irradiating for 30 times, the OSLD sensitivity decreased by approximately 7%. When the OSLDs were irradiated 10 times with 1 Gy after their irradiation using a high dose of 15 Gy and 30 Gy, their sensitivity decreased by 6% and 12%, respectively, compared to that before high-dose irradiation. The change in the OSLD sensitivity with a high dose could be modeled by an exponential equation. We confirmed the radiation sensitivity variation caused by a high dose, and the irradiation history of dosimeters was considered to reuse OSLDs irradiated with a high dose.
关键词： High dose,Co-60,Optically stimulated luminescence dosimeter sensitivity
更新于2025-09-23 15:22:29
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Three-dimensional radiation dosimetry based on optically-stimulated luminescence
摘要： A new approach to three-dimensional (3D) dosimetry based on optically-stimulated luminescence (OSL) is presented. By embedding OSL-active particles into a transparent silicone matrix (PDMS), the well-established dosimetric properties of an OSL material are exploited in a 3D-OSL dosimeter. By investigating prototype dosimeters in standard cuvettes in combination with small test samples for OSL readers, it is shown that a sufficient transparency of the 3D-OSL material can be combined with an OSL response giving an estimated >10.000 detected photons in 1 second per 1mm3 voxel of the dosimeter at a dose of 1 Gy. The dose distribution in the 3D-OSL dosimeters can be directly read out optically without the need for subsequent reconstruction by computational inversion algorithms. The dosimeters carry the advantages known from personal-dosimetry use of OSL: the dose distribution following irradiation can be stored with minimal fading for extended periods of time, and dosimeters are reusable as they can be reset, e.g. by an intense (bleaching) light field.
关键词： optically-stimulated luminescence,silicone matrix,OSL,three-dimensional dosimetry,radiation dosimetry
更新于2025-09-23 15:19:57
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Lanthanide-doped MgO: A case study on how to design new phosphors for dosimetry with tailored luminescent properties
摘要： In this work we systematically investigated undoped and lanthanide(Ln)-doped MgO with diverse dopant combinations, MgO:Ce,Ln and MgO:Tb,Ln, where Ln=Eu, Yb, Tm, Sm, Dy, Nd, as well as the same combinations with an additional 3 mol% Li dopant. We characterized the thermoluminescence (TL), optically stimulated luminescence (OSL), radioluminescence (RL), TL emission spectra and OSL emission spectra. Our investigation indicates that Ce3+ and Tb3+ act as recombination centers and their characteristic spectra are observed under thermal or optical stimulation. Conversely, TL measurements suggests that Sm3+, Tm3+ and Yb3+ probably act as electrons traps. The role of Li was investigated, since it was found to increase the RL, TL and OSL intensities in MgO. As part of the present investigation, we identified promising OSL materials sensitive to ionizing irradiation with distinct luminescent properties.
关键词： Optically stimulated luminescence,Dosimetry,Thermoluminescence,Lanthanides
更新于2025-09-19 17:15:36
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Evaluation of a real-time optically stimulated luminescence beryllium oxide (BeO) fibre-coupled dosimetry system with a superficial 140?kVp X-ray beam
摘要： The purpose of this study was to investigate the potential of real-time optically stimulated luminescence (rtOSL) measurements of a beryllium oxide (BeO) ceramic fibre-coupled luminescence dosimetry system. By pulsing the stimulation laser during the exposure to ionizing radiation, an rtOSL dose-rate measurement can be obtained which could be stem effect free. A portable rtOSL BeO ceramic fibre-coupled dosimetry system is presented and characterized using a constant dose-rate superficial 140 kVp X-ray beam. The rtOSL was measured for dose-rates between 0.29 and 3.88 Gy/min, controlled by varying the source to surface distance. After correcting for OSL decay during the exposure, a linear dose-rate response of the change in rtOSL (ΔrtOSL) was observed. The ΔrtOSL was also observed to be stem effect free.
关键词： Optically stimulated luminescence,Fibre-coupled luminescence dosimetry,BeO ceramic,Stem effect
更新于2025-09-12 10:27:22
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Assessment of scatter radiation dose and absorbed doses in eye lens and thyroid gland during digital breast tomosynthesis
摘要： Digital breast tomosynthesis (DBT) is an alternative tool for breast cancer screening; however, the magnitude of peripheral organs dose is not well known. This study aimed to measure scattered dose and estimate organ dose during mammography under conventional (CM) and Tomo (TM) modes in a specific DBT system. Optically stimulated luminescence dosimeters (OSLDs), whose responses were corrected using a parallel‐plate ionization chamber, were pasted on the surface of custom‐made polymethyl methacrylate (PMMA) and RANDO phantoms to measure entrance surface air kerma (ESAK). ESAK measurements were also acquired with a 4.5‐cm thick breast phantom for a standard mammogram. Organ dose conversion factors (CFD) were determined as ratio of air kerma at a specific depth to that at the surface for the PMMA phantom and multiplied by the ratio of mass energy absorption coefficients of tissue to air. Normalized eye lens and thyroid gland doses were calculated using the RANDO phantom by multiplying CFD and ESAK values. Maximum variability in OSLD response to scatter radiation from the DBT system was 33% in the W/ Rh spectrum and variations in scattered dose distribution were observed between CM and TM. The CFD values for eye lens and thyroid gland ranged between 0.58 to 0.66 and 0.29 to 0.33, respectively. Mean organ doses for two‐view unilateral imaging were 0.24 (CM) and 0.18 (TM) μGy/mAs for the eye lens and 0.24 (CM) and 0.25 (TM) μGy/mAs for the thyroid gland. Higher organ doses were observed during TM compared to CM as the automatic exposure control (AEC) system resulted in greater total mAs values in TM.
关键词： mammography,optically stimulated luminescence dosimeter,eye lens dose,digital breast tomosynthesis,scatter radiation
更新于2025-09-10 09:29:36
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Recovery of α-Al2O3 from Ionizing Radiation Dosimetric Sensors
摘要： Corundum, sapphire or α-Al2O3 is an important technological material in many optical and electronic applications such as solid-state lasers, optical windows and, more recently, as a radiation detector. Landauer (Glenwood, IL, USA) accumulated large number of archived and stored Luxel? dosemeters composed of Al2O3:C, which were subjected to a recovery process. Due to the importance of this advanced crystalline material in OSL dosimetry, a recovery process was developed based on the dosemeters calcination and Al2O3:C has been reused in manufacturing of new dosemeters. This paper does not aim to optimize the recovery process, but provides an opportunity to study the involved process parameters and to recover this valuable crystalline material from used dosemeters. To the best of our knowledge no other recovery process involving this dosimetric material was described in scientific literature. Fourier Transform Infrared Spectrometry (FTIR), Thermogravimetry/Differential Thermoanalysis (TG/DTA), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Optically Stimulated Luminescence (OSL) and Rietveld Refinement were used to characterize the recovered material and to check for the stability of its structural and dosimetric properties.
关键词： recovery process,optically stimulated luminescence,Al2O3:C
更新于2025-09-10 09:29:36
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Radiation induced luminescence properties of pure and Sn-doped 60ZnO.40P2O5 glass
摘要： We have investigated the optical properties and the ionising radiation induced luminescence of xSnO.(60?x)ZnO.40P2O5 (xSZP, x=0, 2·5 and 5) glasses prepared by a conventional melt-quenching method. In optical transmittance measurements, they exhibit 80–90% transparency from UV to visible wavelengths. The photoluminescence quantum yield of the 2.5SZP glass is 95%, with microsecond order decay constants, while that of the Sn-free glass is 3%, with a fast decay time of a few nanoseconds. The peak emission wavelength in scintillation spectra under x-ray irradiation is similar to that in photoluminescence, and appears at around 400 nm. The scintillation decay times of Sn-doped and Sn-free samples under x-ray exposure are a few μs and a few ns, respectively. The thermally stimulated luminescence glow curve was evaluated. For the Sn-doped sample, glow peaks were observed at 210 and 300°C, while the Sn-free sample showed a peak at 150°C. By conducting an initial rise method for trap analysis, the trap depth was found to be 5–10 meV. Optically stimulated luminescence was also examined, and a luminescence peak appeared at around 500 nm with 630 nm stimulation. Based on these results, we propose an energy level diagram of radiation induced luminescence in these glasses.
关键词： scintillation,photoluminescence,thermally stimulated luminescence,Sn-doped zinc phosphate glass,optically stimulated luminescence
更新于2025-09-09 09:28:46
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The Calibration Process of OSL Detectors used for Staff and Patient Dosimetry in Hospital Environment
摘要： The optically stimulated luminescence (OSL-BeO) dosemeter is increasingly being used as a dosimetric technique in various fields such as medical dosimetry. According to our fixed dose protocol, the activities of 3.7-7.4 GBq I-131 source is used for thyroid carcinoma therapy. The in house calibration process for usage of OSL’s at hospital was arranged according to the encapsulated I-131. The measurement point was planned in three different radial distances from source free in air. The dose-rate measurement was done by Geiger-Muller (GM), and then three pieces of OSL was placed in the same positions for one hour. The inverse square law consistency was found (R2=0.99). The calibration coefficient was calculated. For determining the performance of OSL at different dose rates, it used for personnel and patient dosimetry. The average annual dose/2mon to the whole body for all staff by OSL were 0.80 mSv. After administration of 3.7 GBq (100 mCi) therapeutic dose to selected patients, the average pectoral dose was 97.5+32.6 mSv. This calibration process is helpful for confidence of OSL detectors used for dosimetry of staff and patients treated with high activity I-131.
关键词： Calibration process of OSL detectors,Iodine-131,OSL-BeO,Dosimetry of staff and patients,Optically Stimulated Luminescence (OSL)
更新于2025-09-04 15:30:14