Pub Date : 2026-02-01Epub Date: 2025-12-13DOI: 10.1016/j.radmeas.2025.107591
Bruno Winicius Borsoi , Rodrigo Oliveira Bastos , Angelo Zanona Neto , Duvan Gil Rodríguez , João Marcos Fávaro Lopes , Avacir Casanova Andrello , Marcelo Marques Lopes Muller , Cristiano André Pott , Fábio Luiz Melquiades
7Be is a cosmogenic radionuclide used in gamma-ray spectrometry to trace short-term sediment movements, such as soil mobilization. Gamma-ray detectors with low resolution cannot distinguish photons with similar energies, making it challenging to detect 7Be using these instruments. When 7Be decays, it emits gamma rays with an energy of 477 keV, similar to those of other radioisotopes (228Ac, 462 keV; 208Tl, 511 keV) and of the annihilation effect (511 keV). For this reason, high-resolution detectors, such as HPGe, are typically used, as they can differentiate photons and distinguish the mentioned radionuclides which emit similar energies. However, unlike low-resolution detectors, HPGe detectors are much more expensive than other gamma detectors, both in purchase and maintenance costs. These constraints make the widespread use of 7Be measurements for soil erosion studies impractical on a global scale. In this study, we propose a method for analyzing 7Be using a low-resolution scintillation detector, specifically a NaI(Tl) detector. The method eliminates the influences on the 7Be energy window using reference from other spectral regions. The approach was applied to evaluate soil mobilization in two agricultural plots, one with terraces and the other without terraces. The results of 7Be were supported by the measurement of its half-life. Most of the 7Be activity in agricultural soil samples was above the minimum detectable activity, allowing an assessment of the spatial distribution of erosion and deposition rates across the landscape. Soil redistribution was quantitatively evaluated, indicating that terraced soil experiences less erosion than nonterraced soil.
{"title":"7Be measurements in agricultural soil using a low resolution NaI(Tl) detector","authors":"Bruno Winicius Borsoi , Rodrigo Oliveira Bastos , Angelo Zanona Neto , Duvan Gil Rodríguez , João Marcos Fávaro Lopes , Avacir Casanova Andrello , Marcelo Marques Lopes Muller , Cristiano André Pott , Fábio Luiz Melquiades","doi":"10.1016/j.radmeas.2025.107591","DOIUrl":"10.1016/j.radmeas.2025.107591","url":null,"abstract":"<div><div><sup>7</sup>Be is a cosmogenic radionuclide used in gamma-ray spectrometry to trace short-term sediment movements, such as soil mobilization. Gamma-ray detectors with low resolution cannot distinguish photons with similar energies, making it challenging to detect <sup>7</sup>Be using these instruments. When <sup>7</sup>Be decays, it emits gamma rays with an energy of 477 keV, similar to those of other radioisotopes (<sup>228</sup>Ac, 462 keV; <sup>208</sup>Tl, 511 keV) and of the annihilation effect (511 keV). For this reason, high-resolution detectors, such as HPGe, are typically used, as they can differentiate photons and distinguish the mentioned radionuclides which emit similar energies. However, unlike low-resolution detectors, HPGe detectors are much more expensive than other gamma detectors, both in purchase and maintenance costs. These constraints make the widespread use of <sup>7</sup>Be measurements for soil erosion studies impractical on a global scale. In this study, we propose a method for analyzing <sup>7</sup>Be using a low-resolution scintillation detector, specifically a NaI(Tl) detector. The method eliminates the influences on the <sup>7</sup>Be energy window using reference from other spectral regions. The approach was applied to evaluate soil mobilization in two agricultural plots, one with terraces and the other without terraces. The results of <sup>7</sup>Be were supported by the measurement of its half-life. Most of the <sup>7</sup>Be activity in agricultural soil samples was above the minimum detectable activity, allowing an assessment of the spatial distribution of erosion and deposition rates across the landscape. Soil redistribution was quantitatively evaluated, indicating that terraced soil experiences less erosion than nonterraced soil.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107591"},"PeriodicalIF":2.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790455","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 : 2026-02-01Epub Date: 2025-12-17DOI: 10.1016/j.radmeas.2025.107597
H. Sekkat , A. Khallouqi , O. El rhazouani , A. Halimi
This study evaluates the performance of a deep learning model developed to predict organ-specific radiation doses in pediatric head CT scans. The model automates tissue segmentation and voxelization of organs for Monte Carlo (MC) simulations, which provide the ground truth for dose assessment. Using a Python-based framework, the model preprocesses DICOM images, applies HU-based thresholds for tissue classification, and refines segmentation with morphological operations. The segmented tissues, bone, brain matter, eye lens and air + fat, are reconstructed into 3D voxelized volumes, enabling precise dose predictions. A convolutional neural network (CNN) with a pre-trained VGG16 architecture was employed to predict doses based on features extracted from the CT scans and voxelized phantoms. The dataset included 982 pediatric CT scans, with data augmentation techniques applied for model robustness. The model demonstrated high performance in predicting radiation doses, closely matching the MC simulated doses for all organs, with minimal deviations in mean doses and low standard deviations. RRMSE values were low (4.84 % for bone, 6.01 % for brain matter, 8.45 % for air + fat, and 10.59 % for eye lens), indicating high precision. Additionally, the model achieved high R2 values, with bone showing the best correlation (0.95). Performance analysis across 15 random allocations revealed that bone consistently exhibited the highest prediction accuracy, with the lowest median RRMSE (7.84 %) and median MAPE (1.2 %). Although variability was higher for brain matter, eye lens, and air + fat, bone demonstrated superior consistency and accuracy. In conclusion, the deep learning model effectively predicts organ-specific radiation doses for pediatric head CT scans, with particularly high accuracy for bone tissue. While the model shows reliable performance across multiple metrics, further optimization is needed for tissues with higher variability, indicating its promising potential in enhancing radiation dose assessment in pediatric CT.
{"title":"Deep learning-based organ dose prediction in pediatric head CT using fully automated tissue segmentation and newly developed voxelized phantoms in GATE/Geant4 simulation toolkit","authors":"H. Sekkat , A. Khallouqi , O. El rhazouani , A. Halimi","doi":"10.1016/j.radmeas.2025.107597","DOIUrl":"10.1016/j.radmeas.2025.107597","url":null,"abstract":"<div><div>This study evaluates the performance of a deep learning model developed to predict organ-specific radiation doses in pediatric head CT scans. The model automates tissue segmentation and voxelization of organs for Monte Carlo (MC) simulations, which provide the ground truth for dose assessment. Using a Python-based framework, the model preprocesses DICOM images, applies HU-based thresholds for tissue classification, and refines segmentation with morphological operations. The segmented tissues, bone, brain matter, eye lens and air + fat, are reconstructed into 3D voxelized volumes, enabling precise dose predictions. A convolutional neural network (CNN) with a pre-trained VGG16 architecture was employed to predict doses based on features extracted from the CT scans and voxelized phantoms. The dataset included 982 pediatric CT scans, with data augmentation techniques applied for model robustness. The model demonstrated high performance in predicting radiation doses, closely matching the MC simulated doses for all organs, with minimal deviations in mean doses and low standard deviations. RRMSE values were low (4.84 % for bone, 6.01 % for brain matter, 8.45 % for air + fat, and 10.59 % for eye lens), indicating high precision. Additionally, the model achieved high R<sup>2</sup> values, with bone showing the best correlation (0.95). Performance analysis across 15 random allocations revealed that bone consistently exhibited the highest prediction accuracy, with the lowest median RRMSE (7.84 %) and median MAPE (1.2 %). Although variability was higher for brain matter, eye lens, and air + fat, bone demonstrated superior consistency and accuracy. In conclusion, the deep learning model effectively predicts organ-specific radiation doses for pediatric head CT scans, with particularly high accuracy for bone tissue. While the model shows reliable performance across multiple metrics, further optimization is needed for tissues with higher variability, indicating its promising potential in enhancing radiation dose assessment in pediatric CT.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107597"},"PeriodicalIF":2.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790517","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}
Accurate determination of absorbed dose rate to water at the surface of 90Sr-90Y medical β applicators is essential for clinical safety and quality assurance. However, existing methods have inherent limitations: extrapolation chambers are complex and not routinely available in clinical practice, radiochromic films exhibit pronounced energy dependence, and thermoluminescent dosimeters (TLDs) show relatively high measurement uncertainty. In this study, we proposed and validated a practical and traceable method for absorbed dose rate to water measurement using a commercially available parallel-plate ionization chamber (PTW34045). The chamber was calibrated using a certified β radiation standard facility in terms of absorbed dose rate to water at the surface, and its performance was evaluated. A high-precision movable platform was developed to vary the source-to-detector distance with 0.1 mm accuracy. The measured values were corrected for calibrations, environmental conditions, and air-to-water dose conversion. A custom fitting function combining a second-order polynomial and an exponential decay term was employed to extrapolate the absorbed dose rate to water at zero distance. The extrapolated absorbed dose rate values were compared with those provided by manufacturers and independently verified using TLDs calibrated with the same β standard facility. The ionization chamber and TLD measurements agreed within 3–6 %, which is consistent with their combined expanded uncertainties of 5.4 % (k = 2) and 8.8 % (k = 2), while in some cases, significant differences were observed when compared with the values used by the hospitals. Furthermore, Monte Carlo simulations were performed to model the chamber response and validate the measured dose–distance relationship. This approach offers a reliable and clinically applicable solution for β applicator dosimetry, with potential for standardization in routine quality control.
{"title":"Absorbed dose rate to water at the surface of 90Sr-90Y medical β applicators using a parallel-plate ionization Chamber: Towards establishing a traceable method for clinical β applicator dosimetry","authors":"Feixu Ren , Zhonglin Li , Chuan Wu , Ping Huang , Dongkun Xu , Lijuan Feng , Dan Hao , Qingfeng Tang , Songlin Wen , Yuxuan Zhao , Yue Huo","doi":"10.1016/j.radmeas.2025.107590","DOIUrl":"10.1016/j.radmeas.2025.107590","url":null,"abstract":"<div><div>Accurate determination of absorbed dose rate to water at the surface of <sup>90</sup>Sr-<sup>90</sup>Y medical β applicators is essential for clinical safety and quality assurance. However, existing methods have inherent limitations: extrapolation chambers are complex and not routinely available in clinical practice, radiochromic films exhibit pronounced energy dependence, and thermoluminescent dosimeters (TLDs) show relatively high measurement uncertainty. In this study, we proposed and validated a practical and traceable method for absorbed dose rate to water measurement using a commercially available parallel-plate ionization chamber (PTW34045). The chamber was calibrated using a certified β radiation standard facility in terms of absorbed dose rate to water at the surface, and its performance was evaluated. A high-precision movable platform was developed to vary the source-to-detector distance with 0.1 mm accuracy. The measured values were corrected for calibrations, environmental conditions, and air-to-water dose conversion. A custom fitting function combining a second-order polynomial and an exponential decay term was employed to extrapolate the absorbed dose rate to water at zero distance. The extrapolated absorbed dose rate values were compared with those provided by manufacturers and independently verified using TLDs calibrated with the same β standard facility. The ionization chamber and TLD measurements agreed within 3–6 %, which is consistent with their combined expanded uncertainties of 5.4 % (<em>k</em> = 2) and 8.8 % (<em>k</em> = 2), while in some cases, significant differences were observed when compared with the values used by the hospitals. Furthermore, Monte Carlo simulations were performed to model the chamber response and validate the measured dose–distance relationship. This approach offers a reliable and clinically applicable solution for β applicator dosimetry, with potential for standardization in routine quality control.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107590"},"PeriodicalIF":2.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145738028","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}
Enhanced bulk-etch-rate of PADC (polyallyl diglycol carbonate) detectors exposed to gamma rays has been found to be described well as an exponential function of the product of the radiation chemical yield of hydroxyl group (GOH) and the adsorbed dose (D) at different dose-rates between 0.41 and 8.14 Gy/s. The examined absorbed doses were ranging from 30 to 100 kGy, comparable with the local dose in proton tracks. By matching the bulk-etch-rates and the GOH values obtained under identical conditions on dose-rate, the following equation was derived for the relative bulk-etch-rate, Virra/Vb = exp(y･GOH･D), where, Virra and Vb denote the bulk-etch-rates after and before gamma irradiations, respectively, and y is an experimentally obtained constant in a unit of kg/mol, with a value of y = 5.98. In this relation, significant dose-rate dependence is explained as the dose-rate dependence of the GOH value. This means that the radiation damage that increases the bulk-etch-rate is the hydroxyl group itself, and y appears as a constant specific to PADC which relates the damage to bulk-etch-rate. Here, y is termed the “etching coefficient ".
在0.41和8.14 Gy/s之间的不同剂量率下，暴露于伽马射线下的PADC（聚烯丙基碳酸二甘醇）探测器的增强体腐蚀速率可以很好地描述为羟基（GOH）的辐射化学产率和吸附剂量(D)的乘积的指数函数。所检查的吸收剂量范围为30至100千戈瑞，与质子轨道的局部剂量相当。将相同剂量率条件下得到的体蚀率和GOH值进行匹配，得到体蚀率的相对方程Virra/Vb = exp（y弧弧弧弧弧度），其中，Virra和Vb分别表示辐照前后的体蚀率，y为实验得到的常数，单位为kg/mol， y = 5.98。在这个关系中，显著的剂量率依赖性被解释为GOH值的剂量率依赖性。这意味着增加体蚀速率的辐射损伤是羟基本身，y表现为PADC特有的常数，这与体蚀速率的损伤有关。这里，y被称为“蚀刻系数”。
{"title":"Enhanced bulk-etch-rate of gamma irradiated PADC detector expressed by the radiation chemical yield of hydroxyl group","authors":"Reo Yamada , Atsushi Kimoto , Hayato Seiichi , Shunto Sadamitsu , Daisuke Kohinata , Masato Kanasaki , Tamon Kusumoto , Hisashi Kitamura , Satoshi Kodaira , Sachiko Tojo , Tomoya Yamauchi","doi":"10.1016/j.radmeas.2025.107584","DOIUrl":"10.1016/j.radmeas.2025.107584","url":null,"abstract":"<div><div>Enhanced bulk-etch-rate of PADC (polyallyl diglycol carbonate) detectors exposed to gamma rays has been found to be described well as an exponential function of the product of the radiation chemical yield of hydroxyl group (<em>G</em><sub><em>OH</em></sub>) and the adsorbed dose (<em>D</em>) at different dose-rates between 0.41 and 8.14 Gy/s. The examined absorbed doses were ranging from 30 to 100 kGy, comparable with the local dose in proton tracks. By matching the bulk-etch-rates and the <em>G</em><sub><em>OH</em></sub> values obtained under identical conditions on dose-rate, the following equation was derived for the relative bulk-etch-rate, <em>V</em><sub><em>irra</em></sub>/<em>V</em><sub><em>b</em></sub> = exp(<em>y</em>･<em>G</em><sub><em>OH</em></sub>･<em>D</em>), where, <em>V</em><sub><em>irra</em></sub> and <em>V</em><sub><em>b</em></sub> denote the bulk-etch-rates after and before gamma irradiations, respectively, and <em>y</em> is an experimentally obtained constant in a unit of kg/mol, with a value of <em>y</em> = 5.98. In this relation, significant dose-rate dependence is explained as the dose-rate dependence of the <em>G</em><sub><em>OH</em></sub> value. This means that the radiation damage that increases the bulk-etch-rate is the hydroxyl group itself, and <em>y</em> appears as a constant specific to PADC which relates the damage to bulk-etch-rate. Here, <em>y</em> is termed the “etching coefficient \".</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107584"},"PeriodicalIF":2.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683166","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}
A simulation model of a high-purity germanium (HPGe) detector was developed. The detector's parameters were built, and the dead layer thickness was modified according to the result of the measurements of full peak detection efficiency to reach an agreement of better than 5 %. The validation of the Geant4 model was performed using both a point-like source and an extended volumetric source. The validation process shows that the developed Geant4 model is valid for full peak detection efficiency and for performing any additional geometrical and coincidence corrections.
{"title":"Geant4 model to estimate the dead layer thickness of the HPGe detector","authors":"Kafa Al-Khasawneh, Yasser Alsenjlawi, Hadeel Abu-Hejleh, Muflih Alkarazneh","doi":"10.1016/j.radmeas.2025.107585","DOIUrl":"10.1016/j.radmeas.2025.107585","url":null,"abstract":"<div><div>A simulation model of a high-purity germanium (HPGe) detector was developed. The detector's parameters were built, and the dead layer thickness was modified according to the result of the measurements of full peak detection efficiency to reach an agreement of better than 5 %. The validation of the Geant4 model was performed using both a point-like source and an extended volumetric source. The validation process shows that the developed Geant4 model is valid for full peak detection efficiency and for performing any additional geometrical and coincidence corrections.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107585"},"PeriodicalIF":2.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737938","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 : 2026-02-01Epub Date: 2025-12-28DOI: 10.1016/j.radmeas.2025.107603
Renata Majgier
K2SO4:Cu,Na is as a very sensitive phosphor for infrared stimulated luminescence (IRSL), and adding sodium as a co-dopant significantly enhances its dosimetric properties. This study focuses on the initial optimization of the K2SO4:Cu,Na phosphor for use as a passive detector with the IRSL method for reading dose information. Various detector configurations were prepared by mixing the phosphor powder with binders such as Teflon and silicone in different ratios. Key dosimetric characteristics: signal repeatability, dose-response, minimum detectable dose (MDD), and signal fading were evaluated. The dose-response relationship was found to be linear within the range of at least 3 mGy to 1 Gy. In several samples, the MDD was below 1 μGy. The material exhibited ∼50 % signal loss after three months of storage. To address this fading, preheating procedures before IRSL readout were tested, aiming to stabilize the IRSL signal over time. It was shown that preheating prevented signal loss for up to one month post-irradiation, and significantly reduced long-term fading compared to untreated samples. The results highlight the promising potential of K2SO4:Cu,Na phosphor in radiation dosimetry applications.
{"title":"Investigation of the dosimetric properties of K2SO4:Cu,Na detectors with varying phosphor and binder content using infrared-stimulated luminescence (IRSL)","authors":"Renata Majgier","doi":"10.1016/j.radmeas.2025.107603","DOIUrl":"10.1016/j.radmeas.2025.107603","url":null,"abstract":"<div><div>K<sub>2</sub>SO<sub>4</sub>:Cu,Na is as a very sensitive phosphor for infrared stimulated luminescence (IRSL), and adding sodium as a co-dopant significantly enhances its dosimetric properties. This study focuses on the initial optimization of the K<sub>2</sub>SO<sub>4</sub>:Cu,Na phosphor for use as a passive detector with the IRSL method for reading dose information. Various detector configurations were prepared by mixing the phosphor powder with binders such as Teflon and silicone in different ratios. Key dosimetric characteristics: signal repeatability, dose-response, minimum detectable dose (MDD), and signal fading were evaluated. The dose-response relationship was found to be linear within the range of at least 3 mGy to 1 Gy. In several samples, the MDD was below 1 μGy. The material exhibited ∼50 % signal loss after three months of storage. To address this fading, preheating procedures before IRSL readout were tested, aiming to stabilize the IRSL signal over time. It was shown that preheating prevented signal loss for up to one month post-irradiation, and significantly reduced long-term fading compared to untreated samples. The results highlight the promising potential of K<sub>2</sub>SO<sub>4</sub>:Cu,Na phosphor in radiation dosimetry applications.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107603"},"PeriodicalIF":2.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884060","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 : 2026-02-01Epub Date: 2025-11-26DOI: 10.1016/j.radmeas.2025.107571
S. Panzuela , A.M. Bruque , J. Macías
This study investigates the correction of the lateral response artifact (LRA) in accelerated protocols for radiochromic film dosimetry that shorten the time between irradiation and read-out. In these protocols, the LRA is assessed by pixel profiles along the longest axis of radiochromic film strips that are scanned parallel to the axis of artifact. The interplay between the non-uniform response of flatbed scanners and unavoidable heterogeneities in the radiation fields of linear accelerators modifies these pixel profiles, deviating them from their real behavior. This phenomenon has a negative impact on radiochromic film dosimetry. To solve this issue, first-order variations in the homogeneity of the radiation fields were subtracted from the pixel profiles. We studied dose distributions of 30 × 30 cm2 square fields at different dose levels and realistic radiotherapy treatment plans, using 6 MV and 6 MV flattening filter free energies. The radiochromic film models utilized were EBT4 and EBT-XD. For evaluation, gamma analysis (2 %,2 mm) and relative root mean square error metrics were employed. Comparisons against reference measurements demonstrate this novel correction is highly effective in suppressing radiation field heterogeneities, leading to enhanced dosimetric accuracy. Moreover, this study presents a semi-analytical expression for the LRA correction, which contributes to reducing uncertainties.
{"title":"On the correction of lateral response artifact in accelerated radiochromic film dosimetry protocols","authors":"S. Panzuela , A.M. Bruque , J. Macías","doi":"10.1016/j.radmeas.2025.107571","DOIUrl":"10.1016/j.radmeas.2025.107571","url":null,"abstract":"<div><div>This study investigates the correction of the lateral response artifact (LRA) in accelerated protocols for radiochromic film dosimetry that shorten the time between irradiation and read-out. In these protocols, the LRA is assessed by pixel profiles along the longest axis of radiochromic film strips that are scanned parallel to the axis of artifact. The interplay between the non-uniform response of flatbed scanners and unavoidable heterogeneities in the radiation fields of linear accelerators modifies these pixel profiles, deviating them from their real behavior. This phenomenon has a negative impact on radiochromic film dosimetry. To solve this issue, first-order variations in the homogeneity of the radiation fields were subtracted from the pixel profiles. We studied dose distributions of 30 × 30 cm<sup>2</sup> square fields at different dose levels and realistic radiotherapy treatment plans, using 6 MV and 6 MV flattening filter free energies. The radiochromic film models utilized were EBT4 and EBT-XD. For evaluation, gamma analysis (2 %,2 mm) and relative root mean square error metrics were employed. Comparisons against reference measurements demonstrate this novel correction is highly effective in suppressing radiation field heterogeneities, leading to enhanced dosimetric accuracy. Moreover, this study presents a semi-analytical expression for the LRA correction, which contributes to reducing uncertainties.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107571"},"PeriodicalIF":2.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683065","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 : 2026-02-01Epub Date: 2025-12-18DOI: 10.1016/j.radmeas.2025.107594
Zhong-Bin Hang , Chuan-Feng Liu , Yan Zhang , Zi-Wei Liang , Hai Hu , Tian-Tian Zhang , Yun-Tao Liu , Ming-Zhe Song , Ke-Xin Wei , Lin Qin , Xi-Mei Wang , Zuo-Xiang He
Background:
In the clinical application of brachytherapy, the relevant quantities of brachytherapy seed strength must be converted into absorbed dose at a reference depth of 1 cm in water. The current method of obtaining the absorbed dose in water is based on the air kerma strength and dose rate constant, which has an uncertainty of more than 10% (k=2), potentially affecting cancer treatment outcomes.
Purpose:
To ensure accurate dosimetry for 125I brachytherapy seeds, an extrapolation chamber embedded in the water-equivalent material was designed and manufactured to measure the absorbed dose in water directly.
Methods:
The mathematical model for determining the absorbed dose in water is based on radiation transport theory, where the key term conversion factor is determined using the Monte Carlo (MC) methods. In this paper, the basic structure, the measurement method, and the MC simulation of the extrapolation chamber are described. The dose rate constant of the model 6711 125I brachytherapy seed was obtained using three methods (experimental measurement, MC simulation, and AAPM recommended values), and the results was compared and analyzed.
Results:
The absorbed dose in water of the model 6711 125I brachytherapy seed was determined, and after repeated measurements and uncertainty evaluation, the result was 12.39 mGy/h, with an uncertainty of 3.5% (k=2). In addition, the brachytherapy seed was calibrated using an absolute measurement device for the air kerma strength, and its dose rate constant was calculated, which was in good agreement with both the AAPM-recommended values and MC simulated values.
Conclusions:
We successfully developed an absolute measurement device for the absorbed dose in water, which reduced the measurement uncertainty for 125I brachytherapy seeds and achieved dose accuracy for external radiotherapy. This study contributes to the establishment of primary standards for the absorbed dose in water of 125I brachytherapy seeds.
{"title":"Absolute measurement of absorbed dose in water for 125I brachytherapy seeds","authors":"Zhong-Bin Hang , Chuan-Feng Liu , Yan Zhang , Zi-Wei Liang , Hai Hu , Tian-Tian Zhang , Yun-Tao Liu , Ming-Zhe Song , Ke-Xin Wei , Lin Qin , Xi-Mei Wang , Zuo-Xiang He","doi":"10.1016/j.radmeas.2025.107594","DOIUrl":"10.1016/j.radmeas.2025.107594","url":null,"abstract":"<div><h3>Background:</h3><div>In the clinical application of brachytherapy, the relevant quantities of brachytherapy seed strength must be converted into absorbed dose at a reference depth of 1 cm in water. The current method of obtaining the absorbed dose in water is based on the air kerma strength and dose rate constant, which has an uncertainty of more than 10% (<em>k</em>=2), potentially affecting cancer treatment outcomes.</div></div><div><h3>Purpose:</h3><div>To ensure accurate dosimetry for <sup>125</sup>I brachytherapy seeds, an extrapolation chamber embedded in the water-equivalent material was designed and manufactured to measure the absorbed dose in water directly.</div></div><div><h3>Methods:</h3><div>The mathematical model for determining the absorbed dose in water is based on radiation transport theory, where the key term conversion factor <span><math><mrow><mi>C</mi><mrow><mo>(</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>i</mi><mo>+</mo><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>i</mi></mrow></msub><mo>)</mo></mrow></mrow></math></span> is determined using the Monte Carlo (MC) methods. In this paper, the basic structure, the measurement method, and the MC simulation of the extrapolation chamber are described. The dose rate constant of the model 6711 <sup>125</sup>I brachytherapy seed was obtained using three methods (experimental measurement, MC simulation, and AAPM recommended values), and the results was compared and analyzed.</div></div><div><h3>Results:</h3><div>The absorbed dose in water of the model 6711 <sup>125</sup>I brachytherapy seed was determined, and after repeated measurements and uncertainty evaluation, the result was 12.39 mGy/h, with an uncertainty of 3.5% (<em>k</em>=2). In addition, the brachytherapy seed was calibrated using an absolute measurement device for the air kerma strength, and its dose rate constant was calculated, which was in good agreement with both the AAPM-recommended values and MC simulated values.</div></div><div><h3>Conclusions:</h3><div>We successfully developed an absolute measurement device for the absorbed dose in water, which reduced the measurement uncertainty for <sup>125</sup>I brachytherapy seeds and achieved dose accuracy for external radiotherapy. This study contributes to the establishment of primary standards for the absorbed dose in water of <sup>125</sup>I brachytherapy seeds.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107594"},"PeriodicalIF":2.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787322","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 : 2026-02-01Epub Date: 2025-12-17DOI: 10.1016/j.radmeas.2025.107598
A. Romanyukha , J.L. Saunders , J.A. Delzer , A. Smolinski , K. Riley , A. Guynn , A. Tsioplaya , A. Cook
Alanine Electron Paramagnetic Resonance (EPR) dosimetry can measure the total (neutron + photon) dose from a neutron source. Commercially available optically stimulated luminescence (OSL) dosimeters and readers can accurately measure photon doses. An independent measurement of the photon dose contribution is vital because alanine has a different sensitivity to neutrons and photons when calibrated in terms of tissue kerma from 60Co gamma radiation. Therefore, OSL dosimetry can be used to separate neutron and photon dose contributions from the total dose measured by alanine. The Armed Forces Radiobiology Research Institute (AFRRI) research reactor produces varied neutron-photon mixtures, primarily used for radiobiology experiments. Many phantoms at AFRRI are used to measure the accuracy of dose delivery in animal experiments. In the present work, standard and 3D-printed rat phantoms equipped with OSL and alanine dosimeters were used. A special holder capable of securing four alanine pellets and four OSL NanoDot dosimeters was designed and 3D-printed and inserted into the rat phantoms during irradiation. This work was aimed at comparing 3D-printed rat phantoms with the standard PMMA phantom. The results of neutron and photon dose measurements after irradiation in different photon and neutron mixtures are presented. Based on these measurements, the relative neutron sensitivity of alanine was determined to be 0.35 ± 0.11 Gy. Alanine neutron dose measurements were validated using other dosimetry techniques, and further applications of the developed approach are discussed.
{"title":"Application of combined EPR alanine/OSL Al2O3:C dosimetry for neutron and photon dose measurements","authors":"A. Romanyukha , J.L. Saunders , J.A. Delzer , A. Smolinski , K. Riley , A. Guynn , A. Tsioplaya , A. Cook","doi":"10.1016/j.radmeas.2025.107598","DOIUrl":"10.1016/j.radmeas.2025.107598","url":null,"abstract":"<div><div>Alanine Electron Paramagnetic Resonance (EPR) dosimetry can measure the total (neutron + photon) dose from a neutron source. Commercially available optically stimulated luminescence (OSL) dosimeters and readers can accurately measure photon doses. An independent measurement of the photon dose contribution is vital because alanine has a different sensitivity to neutrons and photons when calibrated in terms of tissue kerma from <sup>60</sup>Co gamma radiation. Therefore, OSL dosimetry can be used to separate neutron and photon dose contributions from the total dose measured by alanine. The Armed Forces Radiobiology Research Institute (AFRRI) research reactor produces varied neutron-photon mixtures, primarily used for radiobiology experiments. Many phantoms at AFRRI are used to measure the accuracy of dose delivery in animal experiments. In the present work, standard and 3D-printed rat phantoms equipped with OSL and alanine dosimeters were used. A special holder capable of securing four alanine pellets and four OSL NanoDot dosimeters was designed and 3D-printed and inserted into the rat phantoms during irradiation. This work was aimed at comparing 3D-printed rat phantoms with the standard PMMA phantom. The results of neutron and photon dose measurements after irradiation in different photon and neutron mixtures are presented. Based on these measurements, the relative neutron sensitivity of alanine was determined to be 0.35 ± 0.11 Gy. Alanine neutron dose measurements were validated using other dosimetry techniques, and further applications of the developed approach are discussed.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107598"},"PeriodicalIF":2.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790518","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 : 2026-02-01Epub Date: 2025-12-29DOI: 10.1016/j.radmeas.2025.107587
S. Mohammadian , A. Moslehi , S. Baradaran , M. Sohani
In this work, the response of a boron-doped CR-39 detector in fast neutron fields is modeled using the Geant4 toolkit. A track is counted when the trajectory of a secondary charged particle capable of forming a track passes through the etched thickness at an angle greater than a critical value relative to the CR-39 surface. For a boron concentration of 4%, the calculated track density shows the best agreement with measurements in the 241Am-Be field, with a difference of 7.8%. The model is then used to calculate the track density for several fast neutron energies ranging from 0.1 to 14 MeV. The results reveal that as neutron energy increases, the track density per unit personal dose equivalent decreases. This indicates that the CR-39 sensitivity differs between calibration and measurement fields. Therefore, correcting the CR-39 response is necessary to ensure consistent sensitivity across different neutron energies and to reduce the uncertainty in dose measurements.
{"title":"Geant4 modeling the response of boron-doped CR-39 nuclear track detector in fast neutron fields and its experimental evaluation","authors":"S. Mohammadian , A. Moslehi , S. Baradaran , M. Sohani","doi":"10.1016/j.radmeas.2025.107587","DOIUrl":"10.1016/j.radmeas.2025.107587","url":null,"abstract":"<div><div>In this work, the response of a boron-doped CR-39 detector in fast neutron fields is modeled using the Geant4 toolkit. A track is counted when the trajectory of a secondary charged particle capable of forming a track passes through the etched thickness at an angle greater than a critical value relative to the CR-39 surface. For a boron concentration of 4%, the calculated track density shows the best agreement with measurements in the <sup>241</sup>Am-Be field, with a difference of 7.8%. The model is then used to calculate the track density for several fast neutron energies ranging from 0.1 to 14 MeV. The results reveal that as neutron energy increases, the track density per unit personal dose equivalent decreases. This indicates that the CR-39 sensitivity differs between calibration and measurement fields. Therefore, correcting the CR-39 response is necessary to ensure consistent sensitivity across different neutron energies and to reduce the uncertainty in dose measurements.</div></div>","PeriodicalId":21055,"journal":{"name":"Radiation Measurements","volume":"191 ","pages":"Article 107587"},"PeriodicalIF":2.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884061","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}
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