Pub Date : 2024-10-28DOI: 10.1016/j.radmeas.2024.107324
Guldar Baubekova , Ruslan Assylbayev , Eduard Feldbach , Aleksei Krasnikov , Irina Kudryavtseva , Alise Podelinska , Viktor Seeman , Evgeni Shablonin , Evgeni Vasil'chenko , Aleksandr Lushchik
Single crystals of α-Al2O3 with broad sides oriented perpendicular to the c crystal axis have been irradiated by 231-MeV xenon ions with fluence varying from 5 × 1011 to 1014 ions/cm2. The spectra of radiation-induced optical absorption (absorption of a pristine crystal is subtracted) have been decomposed into Gaussians serving as a measure of oxygen-related Frenkel defects (interstitial-vacancy pairs). The concentration of all structural defects considered – vacancy-type F and F+ centers as well as oxygen interstitials – continuously increases with ion fluence. Therefore, radiation-induced origin of elementary absorption bands at 5.6 and 6.6 eV tentatively ascribed earlier to charged and neutral oxygen interstitials has been proved for the first time. The concentrations of charged interstitials (in the form of superoxide ions) have been directly determined by the EPR method. The evolution of cathodoluminescence bands typical of self-trapped excitons (VUV band at 7.6 eV) and F-type defects (bands peaked around 3.0 and 3.8 eV) with the rise of Xe-ion-irradiation fluence has been measured and analyzed.
α-Al2O3单晶体的宽边方向垂直于晶体的c轴，受到231-MeV氙离子的辐照，离子流量从5×1011到1014个/cm2不等。辐射诱导的光吸收光谱（原始晶体的吸收被减去）被分解成高斯谱，作为与氧有关的弗伦克尔缺陷（间隙空位对）的测量值。所考虑的所有结构缺陷（空位型 F 和 F+ 中心以及氧间隙）的浓度都会随着离子通量的增加而不断增加。因此，之前暂定为带电和中性氧间隙的 5.6 和 6.6 eV 基本吸收带在辐射诱导下的起源首次得到了证实。带电间隙的浓度（以超氧离子的形式）已通过 EPR 方法直接测定。测量并分析了自俘获激子（7.6 eV 处的紫外波段）和 F 型缺陷（3.0 eV 和 3.8 eV 附近的波段峰值）的阴极发光带随 Xe 离子辐照通量的增加而发生的演变。
{"title":"Accumulation of oxygen interstitial-vacancy pairs under irradiation of corundum single crystals with energetic xenon ions","authors":"Guldar Baubekova , Ruslan Assylbayev , Eduard Feldbach , Aleksei Krasnikov , Irina Kudryavtseva , Alise Podelinska , Viktor Seeman , Evgeni Shablonin , Evgeni Vasil'chenko , Aleksandr Lushchik","doi":"10.1016/j.radmeas.2024.107324","DOIUrl":"10.1016/j.radmeas.2024.107324","url":null,"abstract":"<div><div>Single crystals of α-Al<sub>2</sub>O<sub>3</sub> with broad sides oriented perpendicular to the <em>c</em> crystal axis have been irradiated by 231-MeV xenon ions with fluence varying from 5 × 10<sup>11</sup> to 10<sup>14</sup> ions/cm<sup>2</sup>. The spectra of radiation-induced optical absorption (absorption of a pristine crystal is subtracted) have been decomposed into Gaussians serving as a measure of oxygen-related Frenkel defects (interstitial-vacancy pairs). The concentration of all structural defects considered – vacancy-type <em>F</em> and <em>F</em><sup>+</sup> centers as well as oxygen interstitials – continuously increases with ion fluence. Therefore, radiation-induced origin of elementary absorption bands at 5.6 and 6.6 eV tentatively ascribed earlier to charged and neutral oxygen interstitials has been proved for the first time. The concentrations of charged interstitials (in the form of superoxide ions) have been directly determined by the EPR method. The evolution of cathodoluminescence bands typical of self-trapped excitons (VUV band at 7.6 eV) and <em>F</em>-type defects (bands peaked around 3.0 and 3.8 eV) with the rise of Xe-ion-irradiation fluence has been measured and analyzed.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.radmeas.2024.107321
Yves De Deene , Andrew Jirasek
<div><div>Gel dosimetry has emerged over the past three decades in response to a growing need in high-precision radiotherapy to assess, in three dimensions, the absorbed radiation dose, as would be administered in cancer patients.</div><div>Radiation-induced reaction mechanisms are dependent on the class of gel dosimeter, with four classes emerging as primary dosimeters for use in radiation therapy dose verification: (i) Fricke gel dosimeters contain a Fricke solution consisting of ammonium iron (II) sulfate in an acidic solution of sulfuric acid. In Fricke systems an oxidation of ferrous ions results in a change in the nuclear magnetic resonance (NMR) relaxation rate, which enables reading out Fricke gel dosimeters by use of MRI. The radiation-induced oxidation in Fricke gel dosimeters can also be visualized by adding a redox indicator. (ii) Polymer gel dosimeters exploit the radiation induced polymerization reaction of vinyl monomers and are predominantly read out by quantitative MRI or X-ray CT. (iii) Radiochromic dosimeters do not demonstrate a significant radiation-induced change in NMR properties but can be scanned by use of optical scanners (optical CT). In contrast to Fricke gel dosimeters, radiochromic gel dosimeters do not rely on the oxidation of a metal ion but exhibit a color change upon radiation. (iv) Radiofluorogenic dosimeters become fluorescent when exposed to ionizing radiation and can be read out with a planar scanning light beam.</div><div>Likewise, the imaging modality used to extract quantitative dose information depends on the class of dosimeter being used, and three primary imaging modalities have emerged in this context: quantitative MRI, x-ray CT, and optical CT imaging. The accuracy and precision of the dose information extracted from gel dosimetry systems depends on both the dosimetric properties of the gel dosimeters and the readout technique, and the optimal readout method depends on the gel dosimeter response.</div><div>Despite remaining an active field of research and illustrations of the application of gel dosimetry for the validation of clinical dose distributions, the utilization of gel dosimetry as a routine clinical dosimeter has been rather limited. However, with the introduction of new radiotherapy techniques that focus on organ motion compensation, new fractionation schemes, and extreme dose rates, the need for 3D radiation dosimetry is apparent. Even with the need for 3D dosimetry being apparent, gel dosimetry faces continued challenges in areas regarding the extraction of reproducible, accurate, and precise dose information.</div><div>This review paper focuses on an introduction to gel dosimeter classes; a detailed examination of the three readout techniques with emphasis on the achievable accuracy, precision, and optimization of readout parameters; an outlook on future applications in emerging new radiotherapy techniques. We note that the introduction of theragnostic hybrid MRI-Linacs that combine an MR
{"title":"Gel dosimetry: An overview of dosimetry systems and read out methods","authors":"Yves De Deene , Andrew Jirasek","doi":"10.1016/j.radmeas.2024.107321","DOIUrl":"10.1016/j.radmeas.2024.107321","url":null,"abstract":"<div><div>Gel dosimetry has emerged over the past three decades in response to a growing need in high-precision radiotherapy to assess, in three dimensions, the absorbed radiation dose, as would be administered in cancer patients.</div><div>Radiation-induced reaction mechanisms are dependent on the class of gel dosimeter, with four classes emerging as primary dosimeters for use in radiation therapy dose verification: (i) Fricke gel dosimeters contain a Fricke solution consisting of ammonium iron (II) sulfate in an acidic solution of sulfuric acid. In Fricke systems an oxidation of ferrous ions results in a change in the nuclear magnetic resonance (NMR) relaxation rate, which enables reading out Fricke gel dosimeters by use of MRI. The radiation-induced oxidation in Fricke gel dosimeters can also be visualized by adding a redox indicator. (ii) Polymer gel dosimeters exploit the radiation induced polymerization reaction of vinyl monomers and are predominantly read out by quantitative MRI or X-ray CT. (iii) Radiochromic dosimeters do not demonstrate a significant radiation-induced change in NMR properties but can be scanned by use of optical scanners (optical CT). In contrast to Fricke gel dosimeters, radiochromic gel dosimeters do not rely on the oxidation of a metal ion but exhibit a color change upon radiation. (iv) Radiofluorogenic dosimeters become fluorescent when exposed to ionizing radiation and can be read out with a planar scanning light beam.</div><div>Likewise, the imaging modality used to extract quantitative dose information depends on the class of dosimeter being used, and three primary imaging modalities have emerged in this context: quantitative MRI, x-ray CT, and optical CT imaging. The accuracy and precision of the dose information extracted from gel dosimetry systems depends on both the dosimetric properties of the gel dosimeters and the readout technique, and the optimal readout method depends on the gel dosimeter response.</div><div>Despite remaining an active field of research and illustrations of the application of gel dosimetry for the validation of clinical dose distributions, the utilization of gel dosimetry as a routine clinical dosimeter has been rather limited. However, with the introduction of new radiotherapy techniques that focus on organ motion compensation, new fractionation schemes, and extreme dose rates, the need for 3D radiation dosimetry is apparent. Even with the need for 3D dosimetry being apparent, gel dosimetry faces continued challenges in areas regarding the extraction of reproducible, accurate, and precise dose information.</div><div>This review paper focuses on an introduction to gel dosimeter classes; a detailed examination of the three readout techniques with emphasis on the achievable accuracy, precision, and optimization of readout parameters; an outlook on future applications in emerging new radiotherapy techniques. We note that the introduction of theragnostic hybrid MRI-Linacs that combine an MR","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-26DOI: 10.1016/j.radmeas.2024.107323
Maria Karampiperi, Christopher L. Rääf, Christian Bernhardsson
Household salt, Sodium Chloride (NaCl), has been suggested as an appropriate material for retrospective and prospective optically stimulated luminescence (OSL) radiation dosimetry. The current paper investigates the potential application of NaCl pellets during a radiological and/or nuclear emergency, together with an existing portable reader, for application as a novel tool for in situ screening of individual doses in exposed populations.
The evaluation of the portable reader's performance was assessed based on OSL and infra-red stimulated luminescence (IRSL) methods and the results were compared to two research readers, Risø TL/OSL (DA-20 and DA-15). For the studied absorbed dose range (0.63–487 mGy), it was found that five pellets are needed in the portable reader to achieve a similar OSL signal magnitude as using one pellet in the two research readers. The OSL results of the three readers show similar minimum detectable dose (MDD) values and similar linear trends for the obtained OSL dose response curves, within the studied dose range. The IRSL results show a lower IRSL signal for the portable reader, leading to higher MDD values compared to the stationary readers. The MDD can reach down to 2.3 and 47 μGy, respectively, for OSL and IRSL measurements of NaCl with the SUERC portable reader.
Furthermore, sensitization tests show a dose dependent increase in the OSL and IRSL signals. In addition, the possibility of reading the same pellets more than once was confirmed through an advanced protocol, which combines multiple read-outs, and a time delay test. If a combination of OSL and IRSL measurements is applied, it is important to adjust the stimulation length if the first is OSL, while in the case that the first measurement is IRSL, the OSL signal is independent of the IRSL stimulation length.
{"title":"Evaluation of a portable OSL/IRSL reader for radiation dose assessment of NaCl pellets – In situ individualised screening during R/N emergencies","authors":"Maria Karampiperi, Christopher L. Rääf, Christian Bernhardsson","doi":"10.1016/j.radmeas.2024.107323","DOIUrl":"10.1016/j.radmeas.2024.107323","url":null,"abstract":"<div><div>Household salt, Sodium Chloride (NaCl), has been suggested as an appropriate material for retrospective and prospective optically stimulated luminescence (OSL) radiation dosimetry. The current paper investigates the potential application of NaCl pellets during a radiological and/or nuclear emergency, together with an existing portable reader, for application as a novel tool for <em>in situ</em> screening of individual doses in exposed populations.</div><div>The evaluation of the portable reader's performance was assessed based on OSL and infra-red stimulated luminescence (IRSL) methods and the results were compared to two research readers, Risø TL/OSL (DA-20 and DA-15). For the studied absorbed dose range (0.63–487 mGy), it was found that five pellets are needed in the portable reader to achieve a similar OSL signal magnitude as using one pellet in the two research readers. The OSL results of the three readers show similar minimum detectable dose (MDD) values and similar linear trends for the obtained OSL dose response curves, within the studied dose range. The IRSL results show a lower IRSL signal for the portable reader, leading to higher MDD values compared to the stationary readers. The MDD can reach down to 2.3 and 47 μGy, respectively, for OSL and IRSL measurements of NaCl with the SUERC portable reader.</div><div>Furthermore, sensitization tests show a dose dependent increase in the OSL and IRSL signals. In addition, the possibility of reading the same pellets more than once was confirmed through an advanced protocol, which combines multiple read-outs, and a time delay test. If a combination of OSL and IRSL measurements is applied, it is important to adjust the stimulation length if the first is OSL, while in the case that the first measurement is IRSL, the OSL signal is independent of the IRSL stimulation length.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.radmeas.2024.107322
Vo Hong Hai , Nguyen Quoc Hung , Nguyen Tri Toan Phuc , Masaharu Nomachi
This study investigates the contributions of various cosmic-ray-induced components to the energy response of a High-Purity Germanium (HPGe) gamma spectrometer within the 0°–45° zenith angle range. The analysis focuses on muons, neutrons, protons, electrons, positrons, and photons. It also examines the impact of particle showers induced by muons interacting with the lead chamber and reaching the HPGe detector. Utilizing the GEANT4 simulation toolkit, we provide a detailed examination of these components' influence on the spectrum. The results confirm that within this zenith angle range, muons account for approximately 91% of the recorded cosmic-ray induced energy spectrum and contribute 54.6% to the overall cosmic-ray-induced background spectrum. The study also highlights the significant role of showers, especially those resulting from muon interactions with the lead shielding, in shaping the low-energy spectrum below 3 MeV.
{"title":"Contributions of cosmic-ray components to the HPGe gamma spectrometer background spectrum within the 0°–45° Zenith angle range","authors":"Vo Hong Hai , Nguyen Quoc Hung , Nguyen Tri Toan Phuc , Masaharu Nomachi","doi":"10.1016/j.radmeas.2024.107322","DOIUrl":"10.1016/j.radmeas.2024.107322","url":null,"abstract":"<div><div>This study investigates the contributions of various cosmic-ray-induced components to the energy response of a High-Purity Germanium (HPGe) gamma spectrometer within the 0°–45° zenith angle range. The analysis focuses on muons, neutrons, protons, electrons, positrons, and photons. It also examines the impact of particle showers induced by muons interacting with the lead chamber and reaching the HPGe detector. Utilizing the GEANT4 simulation toolkit, we provide a detailed examination of these components' influence on the spectrum. The results confirm that within this zenith angle range, muons account for approximately 91% of the recorded cosmic-ray induced energy spectrum and contribute 54.6% to the overall cosmic-ray-induced background spectrum. The study also highlights the significant role of showers, especially those resulting from muon interactions with the lead shielding, in shaping the low-energy spectrum below 3 MeV.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-17DOI: 10.1016/j.radmeas.2024.107309
P.K. Witter , B. Champine , A.S. Tamashiro , P. Maggi
A Nuclear Accident Dosimetry program is a federal requirement for all facilities that have the potential to have a criticality accident. Personnel Nuclear Accident Dosimeter (PNAD) theory and analytical procedures are driven by various scientific needs and interacting regulations. A brief history of the status of USA Department of Energy (DOE) nuclear accident dosimetry regulations, recommendations, and performance testing criteria are given. Then, the history of the Lawrence Livermore National Laboratory (LLNL) PNAD is explored, including changes in the physical dosimeter and adjustments of the analysis method through the last four decades. Finally, the performance of LLNL’s PNAD at criticality accident intercomparison training exercises since 2009 is explored. In general, reported neutron doses have been within or close to DOE-STD-1098 performance criteria while reported gamma doses have been outside of DOE-STD-1098 performance criteria. Reported total absorbed doses have varied in meeting ANSI/HPS N13.3 and ANSI/HPS N13.3 (R2019) performance criteria. Dosimetry staff retirement and turnover have left historical knowledge gaps, yet provided opportunities within the NAD program at LLNL. This review paper serves as an overview of the history and status of the NAD program. Brief technical, procedural and programmatic recommendations to improve LLNL’s NAD program are given. Technical recommendations include investigating orientation factors through modeling or empirical experimentation, investigating gamma dosimetry methods for high-dose scenarios, and exploring other dosimetric methods for simpler, quicker NAD analysis. Procedural recommendations include better documentation of conversion factor (activity-to-fluence and fluence-to-dose) derivations and spectrum uses, and updated analysis spreadsheets or simple Graphic User Interfaces for dose calculations. Programmatic recommendations include formalized training for NAD analysts, and having multiple SMEs trained on the NAD program.
核事故剂量测定计划是联邦对所有可能发生临界事故的设施的要求。人员核事故剂量计 (PNAD) 理论和分析程序受各种科学需求和交互法规的驱动。本文简要介绍了美国能源部（DOE）核事故剂量测定法规、建议和性能测试标准的现状。然后，探讨了劳伦斯利弗莫尔国家实验室（LLNL）PNAD 的历史，包括过去四十年中物理剂量计的变化和分析方法的调整。最后，探讨了劳伦斯利弗莫尔国家实验室的 PNAD 自 2009 年以来在临界事故相互比对训练演习中的表现。总体而言，报告的中子剂量一直在 DOE-STD-1098 性能标准之内或接近该标准，而报告的伽马剂量一直在 DOE-STD-1098 性能标准之外。报告的总吸收剂量在满足 ANSI/HPS N13.3 和 ANSI/HPS N13.3 (R2019) 性能标准方面存在差异。剂量测定人员的退休和流动留下了历史性的知识空白，但也为 LLNL 的 NAD 计划提供了机会。本回顾文件概述了 NAD 计划的历史和现状。文中简要介绍了改进 LLNL NAD 计划的技术、程序和计划建议。技术建议包括通过建模或经验实验研究定向因素，研究高剂量情况下的伽马剂量测定方 法，以及探索其他剂量测定方法以进行更简单、更快速的 NAD 分析。程序方面的建议包括更好地记录转换系数（放射性活度-荧光和荧光-剂量）的推导和频谱用途，更新剂量计算的分析电子表格或简单的图形用户界面。程序方面的建议包括对 NAD 分析人员进行正式培训，以及让多个 SME 接受 NAD 程序方面的培训。
{"title":"A Review of the Lawrence Livermore Nuclear Accident Dosimeter 1980s-present","authors":"P.K. Witter , B. Champine , A.S. Tamashiro , P. Maggi","doi":"10.1016/j.radmeas.2024.107309","DOIUrl":"10.1016/j.radmeas.2024.107309","url":null,"abstract":"<div><div>A Nuclear Accident Dosimetry program is a federal requirement for all facilities that have the potential to have a criticality accident. Personnel Nuclear Accident Dosimeter (PNAD) theory and analytical procedures are driven by various scientific needs and interacting regulations. A brief history of the status of USA Department of Energy (DOE) nuclear accident dosimetry regulations, recommendations, and performance testing criteria are given. Then, the history of the Lawrence Livermore National Laboratory (LLNL) PNAD is explored, including changes in the physical dosimeter and adjustments of the analysis method through the last four decades. Finally, the performance of LLNL’s PNAD at criticality accident intercomparison training exercises since 2009 is explored. In general, reported neutron doses have been within or close to DOE-STD-1098 performance criteria while reported gamma doses have been outside of DOE-STD-1098 performance criteria. Reported total absorbed doses have varied in meeting ANSI/HPS N13.3 and ANSI/HPS N13.3 (R2019) performance criteria. Dosimetry staff retirement and turnover have left historical knowledge gaps, yet provided opportunities within the NAD program at LLNL. This review paper serves as an overview of the history and status of the NAD program. Brief technical, procedural and programmatic recommendations to improve LLNL’s NAD program are given. Technical recommendations include investigating orientation factors through modeling or empirical experimentation, investigating gamma dosimetry methods for high-dose scenarios, and exploring other dosimetric methods for simpler, quicker NAD analysis. Procedural recommendations include better documentation of conversion factor (activity-to-fluence and fluence-to-dose) derivations and spectrum uses, and updated analysis spreadsheets or simple Graphic User Interfaces for dose calculations. Programmatic recommendations include formalized training for NAD analysts, and having multiple SMEs trained on the NAD program.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-16DOI: 10.1016/j.radmeas.2024.107310
Lily Bossin , Riccardo Dal Bello , Jeppe Brage Christensen , Stefan Schischke , Silvia Motta , Michele Togno , Eduardo Gardenali Yukihara
This study aims to evaluate the performance of the BeO-based myOSLchip system (RadPro International GmbH, Remscheid, Germany) for dosimetry of proton and electron radiotherapy beams. Although beryllium oxide (BeO) has been recognised as a promising material for luminescence dosimetry in radiotherapy, this research extends beyond material properties and examines the entire BeO-based dosimetry system, including the detector, holder, and readout components.
Packages of myOSLchip dosimeters were irradiated either in a () MeV proton beam or in a 16 MeV electron beam. The readouts were carried out using the portable myOSLchip reader. In the electron beam, tests on the precision, dose response up to 100 Gy and dose-rate effects of the system were carried out. In the proton beam, the system was tested for its dose response (up to 10 Gy), fading, and linear energy transfer (LET) response.
For proton irradiations, the myOSLchip BeO OSLDs exhibited stability within 2% over 135 days, as well as a linear dose response in the tested range, () Gy. The efficiency showed a reduction for proton beams with LET values (for water) above 0.6 keV/m, with up to 40% loss in efficiency at 4 keV/m. For the electron irradiations, they showed a linear dose–response up to 20 Gy and dose-rate independence, with a constant response at least up to 2.99 × 105 Gy s−1. Using individual dosimeter sensitivity correction, the precision for a single dosimeter was around 3.5% (standard deviation of the data of all dosimeters) and for a package comprising four dosimeters was 1.7% (standard deviation of the mean of the four dosimeters).
These findings suggest the myOSLchip system’s potential as a reliable alternative to existing dosimetry systems in clinical applications.
{"title":"Performance of a BeO-based dosimetry system for proton and electron beam dose measurements","authors":"Lily Bossin , Riccardo Dal Bello , Jeppe Brage Christensen , Stefan Schischke , Silvia Motta , Michele Togno , Eduardo Gardenali Yukihara","doi":"10.1016/j.radmeas.2024.107310","DOIUrl":"10.1016/j.radmeas.2024.107310","url":null,"abstract":"<div><div>This study aims to evaluate the performance of the BeO-based myOSLchip system (RadPro International GmbH, Remscheid, Germany) for dosimetry of proton and electron radiotherapy beams. Although beryllium oxide (BeO) has been recognised as a promising material for luminescence dosimetry in radiotherapy, this research extends beyond material properties and examines the entire BeO-based dosimetry system, including the detector, holder, and readout components.</div><div>Packages of myOSLchip dosimeters were irradiated either in a (<span><math><mrow><mn>70</mn><mo>−</mo><mn>230</mn></mrow></math></span>) MeV proton beam or in a 16 MeV electron beam. The readouts were carried out using the portable myOSLchip reader. In the electron beam, tests on the precision, dose response up to 100 Gy and dose-rate effects of the system were carried out. In the proton beam, the system was tested for its dose response (up to 10 Gy), fading, and linear energy transfer (LET) response.</div><div>For proton irradiations, the myOSLchip BeO OSLDs exhibited stability within 2% over 135 days, as well as a linear dose response in the tested range, (<span><math><mrow><mn>0</mn><mo>.</mo><mn>1</mn><mo>−</mo><mn>10</mn></mrow></math></span>) Gy. The efficiency showed a reduction for proton beams with LET values (for water) above 0.6 keV/<span><math><mi>μ</mi></math></span>m, with up to 40% loss in efficiency at 4 keV/<span><math><mi>μ</mi></math></span>m. For the electron irradiations, they showed a linear dose–response up to 20 Gy and dose-rate independence, with a constant response at least up to 2.99 × 10<sup>5</sup> Gy s<sup>−1</sup>. Using individual dosimeter sensitivity correction, the precision for a single dosimeter was around 3.5% (standard deviation of the data of all dosimeters) and for a package comprising four dosimeters was 1.7% (standard deviation of the mean of the four dosimeters).</div><div>These findings suggest the myOSLchip system’s potential as a reliable alternative to existing dosimetry systems in clinical applications.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142526728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-16DOI: 10.1016/j.radmeas.2024.107320
Hiroki Kawamoto, Yutaka Fujimoto, Keisuke Asai
Radiophotoluminescence (RPL) is the phenomenon of emission from luminescence centers formed by ionizing radiation (RPL centers) and is applied in dosimeters. Knowledge regarding the development of RPL materials is limited and development of new RPL materials is required. In this study, we investigate the RPL properties of Au-doped soda-lime silicate glass. After X-ray irradiation, an emission band appeared at 650–900 nm upon excitation at 330 nm, and the emission intensity increased linearly in the dose range of 3.72–100 Gy. The UV–vis absorption, photoluminescence, and electron spin resonance spectroscopy revealed that the Au dimer, non-bridged oxygen hole center, and E’ center (electrons trapped in the glass host) were formed by ionizing radiation. The Au dimer acts as the RPL center. In addition, build-up, that is, progressive formation of RPL centers at room temperature, was completed in 20 min, and bleaching by 330 nm light was induced in Au-doped soda-lime silicate glass.
{"title":"Radiophotoluminescence from Au-doped soda-lime silicate glass","authors":"Hiroki Kawamoto, Yutaka Fujimoto, Keisuke Asai","doi":"10.1016/j.radmeas.2024.107320","DOIUrl":"10.1016/j.radmeas.2024.107320","url":null,"abstract":"<div><div>Radiophotoluminescence (RPL) is the phenomenon of emission from luminescence centers formed by ionizing radiation (RPL centers) and is applied in dosimeters. Knowledge regarding the development of RPL materials is limited and development of new RPL materials is required. In this study, we investigate the RPL properties of Au-doped soda-lime silicate glass. After X-ray irradiation, an emission band appeared at 650–900 nm upon excitation at 330 nm, and the emission intensity increased linearly in the dose range of 3.72–100 Gy. The UV–vis absorption, photoluminescence, and electron spin resonance spectroscopy revealed that the Au dimer, non-bridged oxygen hole center, and E’ center (electrons trapped in the glass host) were formed by ionizing radiation. The Au dimer acts as the RPL center. In addition, build-up, that is, progressive formation of RPL centers at room temperature, was completed in 20 min, and bleaching by 330 nm light was induced in Au-doped soda-lime silicate glass.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142526722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Boron neutron capture therapy (BNCT) is a radiotherapy technology that selectively kills tumor cells via the 10B(n, α)7Li reactions. Epithermal neutrons (0.5 eV–10 keV) are emitted and converted into thermal neutrons, which have a larger neutron capture reaction cross-section, by slowing down in the human body before reaching the tumor. Recently, the development of an epithermal neutron absolute flux intensity measurement technique has become crucial for real-time in-vivo dose monitoring in BNCT. In this study, a concept for a measurement system consisting of multiple compact scintillator with optical fibers detectors covered with neutron absorbers of various thicknesses is proposed. The designed system achieves a consistent response to epithermal neutrons with a theoretical coefficient of variation not higher than 5% for both LiCAF and EJ-254 scintillators. The theoretical feasibility of the proposed measurement system was investigated by an irradiation experiment carried out at the heavy water neutron irradiation facility at the Kyoto University Reactor. The experimental results indicated that further improvement and refinement are necessary to meet the high accuracy and precision required for real-time dose monitoring in clinical applications.
{"title":"Preliminary study of a compact epithermal neutron absolute flux intensity measurement system for real-time in-vivo dose monitoring in boron neutron capture therapy","authors":"Jiye Qiu , Daisuke Hatano , Yulin Ge , Nikolaos Voulgaris , Kohei Sagara , Zhaopeng Qiao , Shingo Tamaki , Sachie Kusaka , Takushi Takata , Isao Murata","doi":"10.1016/j.radmeas.2024.107308","DOIUrl":"10.1016/j.radmeas.2024.107308","url":null,"abstract":"<div><div>Boron neutron capture therapy (BNCT) is a radiotherapy technology that selectively kills tumor cells via the <sup>10</sup>B(n, <em>α</em>)<sup>7</sup>Li reactions. Epithermal neutrons (0.5 eV–10 keV) are emitted and converted into thermal neutrons, which have a larger neutron capture reaction cross-section, by slowing down in the human body before reaching the tumor. Recently, the development of an epithermal neutron absolute flux intensity measurement technique has become crucial for real-time in-vivo dose monitoring in BNCT. In this study, a concept for a measurement system consisting of multiple compact scintillator with optical fibers detectors covered with neutron absorbers of various thicknesses is proposed. The designed system achieves a consistent response to epithermal neutrons with a theoretical coefficient of variation not higher than 5% for both LiCAF and EJ-254 scintillators. The theoretical feasibility of the proposed measurement system was investigated by an irradiation experiment carried out at the heavy water neutron irradiation facility at the Kyoto University Reactor. The experimental results indicated that further improvement and refinement are necessary to meet the high accuracy and precision required for real-time dose monitoring in clinical applications.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.radmeas.2024.107305
S. Motta, E.G. Yukihara
This work investigates theoretically possible dose rate effects in thermoluminescence (TL) and optically stimulated luminescence (OSL) materials by solving the rate equations for the stimulated luminescence process. Starting with the solution of the One-Trap–One-Recombination-Center (OTOR) model with parameters from the literature, we first showed that this model, with the chosen parameters, does not reproduce real luminescent material properties (e.g., TL curve and dose response). We then studied the physical phenomena responsible for dose rate effects in this model, and the influence of the model parameters on the dose rate response. As a result, we found that charge accumulation in the delocalized bands over unrealistic long periods ( hundreds of seconds) is responsible for dose rate effects. Such effect is caused by the particular choice of model parameters. When model parameters based on physical considerations and experimental results are chosen, no dose rate effects are observed. This work provides a deeper understanding of the luminescence process, by identifying the mechanisms that could be responsible for dose rate effects, and a theoretical foundation to the use of luminescent detectors for ultra-high dose rate dosimetry.
{"title":"Assessing dose rate effects in TL and OSL dosimeters: A critical look into dose rate models","authors":"S. Motta, E.G. Yukihara","doi":"10.1016/j.radmeas.2024.107305","DOIUrl":"10.1016/j.radmeas.2024.107305","url":null,"abstract":"<div><div>This work investigates theoretically possible dose rate effects in thermoluminescence (TL) and optically stimulated luminescence (OSL) materials by solving the rate equations for the stimulated luminescence process. Starting with the solution of the One-Trap–One-Recombination-Center (OTOR) model with parameters from the literature, we first showed that this model, with the chosen parameters, does not reproduce real luminescent material properties (e.g., TL curve and dose response). We then studied the physical phenomena responsible for dose rate effects in this model, and the influence of the model parameters on the dose rate response. As a result, we found that charge accumulation in the delocalized bands over unrealistic long periods (<span><math><mo>></mo></math></span> hundreds of seconds) is responsible for dose rate effects. Such effect is caused by the particular choice of model parameters. When model parameters based on physical considerations and experimental results are chosen, no dose rate effects are observed. This work provides a deeper understanding of the luminescence process, by identifying the mechanisms that could be responsible for dose rate effects, and a theoretical foundation to the use of luminescent detectors for ultra-high dose rate dosimetry.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142526726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-09DOI: 10.1016/j.radmeas.2024.107307
Jonathan Eakins , Michael Discher , Hyoungtaek Kim , Min Chae Kim , Hanjin Lee , Jungil Lee , Olivier Van Hoey , Hyungjoon Yu , Elizabeth Ainsbury , Céline Bassinet , Stephen McKeever , Sergey Sholom , Francois Trompier , Lovisa Waldner , Clemens Woda
Dose conversion coefficients attempt to harmonize the material-, location-, and exposure-dependent results from retrospective dosemeters. The issues and uncertainties arising from dose conversion are explored within the framework of an interlaboratory comparison exercise in which mobile phones were positioned around anthropomorphic phantoms and exposed to non-uniform photon fields, with the glass and resistors they contain employed as fortuitous dosemeters. The difficulties of adopting pre-calculated tables of generic conversion coefficients are evaluated first, and then compared against those arising through the use of bespoke data derived by Monte Carlo modelling, and also against not converting the doses measured by the phones. It is seen that the different subjective choices that users might make when selecting ‘optimal’ generic data can lead to a significant source of uncertainty (up to around 70 %), though may be improved (to around 30 %) by appropriate quality controls. Use of generic coefficients typically led to over-estimates of the organ doses: an average discrepancy of ca. a factor of 2 was found, but this is still better than the factor of around 3 observed when no conversion coefficients were applied. Use of bespoke conversion factors led to the best estimates of organ doses, although they still over-estimated by approximately 1.5 on average, and an uncertainty of around 20 % was associated with generating their values. Overall, applying bespoke conversion data improves but does not guarantee correct dose categorization of individuals, with the inconsistences in the measured results found generally to be the limiting factor in obtaining accurate dose assessments.
{"title":"Dose conversion in retrospective dosimetry: Results and implications from an inter-laboratory comparison featuring a realistic exposure scenario","authors":"Jonathan Eakins , Michael Discher , Hyoungtaek Kim , Min Chae Kim , Hanjin Lee , Jungil Lee , Olivier Van Hoey , Hyungjoon Yu , Elizabeth Ainsbury , Céline Bassinet , Stephen McKeever , Sergey Sholom , Francois Trompier , Lovisa Waldner , Clemens Woda","doi":"10.1016/j.radmeas.2024.107307","DOIUrl":"10.1016/j.radmeas.2024.107307","url":null,"abstract":"<div><div>Dose conversion coefficients attempt to harmonize the material-, location-, and exposure-dependent results from retrospective dosemeters. The issues and uncertainties arising from dose conversion are explored within the framework of an interlaboratory comparison exercise in which mobile phones were positioned around anthropomorphic phantoms and exposed to non-uniform photon fields, with the glass and resistors they contain employed as fortuitous dosemeters. The difficulties of adopting pre-calculated tables of generic conversion coefficients are evaluated first, and then compared against those arising through the use of bespoke data derived by Monte Carlo modelling, and also against not converting the doses measured by the phones. It is seen that the different subjective choices that users might make when selecting ‘optimal’ generic data can lead to a significant source of uncertainty (up to around 70 %), though may be improved (to around 30 %) by appropriate quality controls. Use of generic coefficients typically led to over-estimates of the organ doses: an average discrepancy of ca. a factor of 2 was found, but this is still better than the factor of around 3 observed when no conversion coefficients were applied. Use of bespoke conversion factors led to the best estimates of organ doses, although they still over-estimated by approximately 1.5 on average, and an uncertainty of around 20 % was associated with generating their values. Overall, applying bespoke conversion data improves but does not guarantee correct dose categorization of individuals, with the inconsistences in the measured results found generally to be the limiting factor in obtaining accurate dose assessments.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142526727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号