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The Use of Joint Models in Analysis of Aggregate Endpoints in RERF Cohort Studies. 在 RERF 队列研究的总体终点分析中使用联合模型。
IF 2.5 3区 医学
Radiation research Pub Date : 2024-04-01 DOI: 10.1667/RADE-23-00122.1
Richard Sposto, Harry M Cullings
{"title":"The Use of Joint Models in Analysis of Aggregate Endpoints in RERF Cohort Studies.","authors":"Richard Sposto, Harry M Cullings","doi":"10.1667/RADE-23-00122.1","DOIUrl":"10.1667/RADE-23-00122.1","url":null,"abstract":"<p><p>In radiation risk estimation based on the Radiation Effects Research Foundation (RERF) cohort studies, one common analysis is Poisson regression on radiation dose and background and effect modifying variables of an aggregate endpoint such as all solid cancer incidence or all non-cancer mortality. As currently performed, these analyses require selection of a surrogate radiation organ dose, (e.g., colon dose), which could conceptually be problematic since the aggregate endpoint comprises events arising from a variety of organs. We use maximum likelihood theory to compare inference from the usual aggregate endpoint analysis to analyses based on joint analysis. These two approaches are also compared in a re-analysis of RERF Life Span Study all cancer mortality. We show that, except for a trivial difference, these two analytic approaches yield identical inference with respect to radiation dose response and background and effect modification when based on a single surrogate organ radiation dose. When repeating the analysis with organ-specific doses, an interesting issue of bias in intercept parameters arises when dose estimates are undefined for one sex when sex-specific outcomes are included in the aggregate endpoint, but a simple correction will avoid this issue. Lastly, while the joint analysis formulation allows use of organ-specific doses, the interpretation of such an analysis for inference regarding an aggregate endpoint can be problematic. To the extent that analysis of radiation risk for an aggregate endpoint is of interest, the joint-analysis formulation with a single surrogate dose is an appropriate analytic approach, whereas joint analysis with organ-specific doses may only be interpretable if endpoints are considered separately for estimating dose response. However, for neither approach is inference about dose response well defined.</p>","PeriodicalId":20903,"journal":{"name":"Radiation research","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139723860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Dose Rate Effects on Hydrated Electrons, Hydrogen Peroxide, and a OH Radical Molecular Probe Under Clinical Energy Protons. 临床能量质子对水合电子、过氧化氢和 OH 自由基分子探针的剂量率影响。
IF 2.5 3区 医学
Radiation research Pub Date : 2024-04-01 DOI: 10.1667/RADE-23-00244.1
Tamon Kusumoto, Antoine Danvin, Taisei Mamiya, Aurelia Arnone, Severine Chefson, Catherine Galindo, Philippe Peaupardin, Quentin Raffy, Nagaaki Kamiguchi, Daizo Amano, Kenzo Sasai, Teruaki Konishi, Satoshi Kodaira
{"title":"Dose Rate Effects on Hydrated Electrons, Hydrogen Peroxide, and a OH Radical Molecular Probe Under Clinical Energy Protons.","authors":"Tamon Kusumoto, Antoine Danvin, Taisei Mamiya, Aurelia Arnone, Severine Chefson, Catherine Galindo, Philippe Peaupardin, Quentin Raffy, Nagaaki Kamiguchi, Daizo Amano, Kenzo Sasai, Teruaki Konishi, Satoshi Kodaira","doi":"10.1667/RADE-23-00244.1","DOIUrl":"10.1667/RADE-23-00244.1","url":null,"abstract":"<p><p>We report the dose rate dependence of radiation chemical yields (G value) of water radiolysis products under clinical energy protons (230 MeV) to understand mechanisms of the FLASH radiotherapy performed at ultra-high dose rate (>40 Gy/s). The G value of 7-hydoroxy-coumarin-3-carboxylic acid (7OH-C3CA) produced by reactions of coumarin-3-carboxylic acid (C3CA) with OH radicals and oxygen is evaluated by fluorescence method. Also, those of hydrated electrons and hydrogen peroxide are derived by absorption method using Saltzman and Ghomley techniques, respectively. Both G values of 7OH-C3CA and hydrated electrons decrease with increasing dose rate. The relative evolution of 7OH-C3CA is -39 ± 2% between 0.1 and 50 Gy/s. This value is higher than that of hydrated electrons, measured at -21 ± 4%. The G value of hydrogen peroxide in ultra-pure water also decreases with increasing dose rate. In comparison to these findings, we represent the increase of the G value of hydrogen peroxide with increasing dose rate in the mixture solution of MeOH and NaNO3, which act as scavengers of OH radicals and hydrated electrons, respectively, that decompose hydrogen peroxide. This finding indicates that a complex track structure can be expected with increasing dose rate and the reduction of OH radicals by forming hydrogen peroxide would be related to the sparing effect of healthy tissues.</p>","PeriodicalId":20903,"journal":{"name":"Radiation research","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139973295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Achieving Consistent Reporting of Radiation Dosimetry by Adoption of Compatibility in Irradiation Research Protocols Expert Roundtable (CIRPER) Recommendations. 通过采用辐照研究协议兼容性专家圆桌会议(CIRPER)的建议,实现辐射剂量测量报告的一致性。
IF 2.5 3区 医学
Radiation research Pub Date : 2024-03-01 DOI: 10.1667/RADE-23-00234.1
Warren Stern, Parham Alaei, Ross Berbeco, Larry A DeWerd, Jacob Kamen, Carolyn MacKenzie, Eduardo G Moros, Yannick Poirier, Charles A Potter, Dörthe Schaue, Ileana Silvestre Patallo, Michael Abend, Steven Swarts, François Trompier
{"title":"Achieving Consistent Reporting of Radiation Dosimetry by Adoption of Compatibility in Irradiation Research Protocols Expert Roundtable (CIRPER) Recommendations.","authors":"Warren Stern, Parham Alaei, Ross Berbeco, Larry A DeWerd, Jacob Kamen, Carolyn MacKenzie, Eduardo G Moros, Yannick Poirier, Charles A Potter, Dörthe Schaue, Ileana Silvestre Patallo, Michael Abend, Steven Swarts, François Trompier","doi":"10.1667/RADE-23-00234.1","DOIUrl":"10.1667/RADE-23-00234.1","url":null,"abstract":"","PeriodicalId":20903,"journal":{"name":"Radiation research","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139417956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
YBX1 Underwent Phase Separation into Stress Granules Stimulated by Ionizing Radiation. 在电离辐射的刺激下,YBX1 发生相分离,形成应激颗粒。
IF 2.5 3区 医学
Radiation research Pub Date : 2024-03-01 DOI: 10.1667/RADE-23-00113.1
Jiaxin Tang, Jiyuan Liu, Jing Nie, Hailong Pei, Guangming Zhou
{"title":"YBX1 Underwent Phase Separation into Stress Granules Stimulated by Ionizing Radiation.","authors":"Jiaxin Tang, Jiyuan Liu, Jing Nie, Hailong Pei, Guangming Zhou","doi":"10.1667/RADE-23-00113.1","DOIUrl":"10.1667/RADE-23-00113.1","url":null,"abstract":"<p><p>Stress granules (SGs) are formed through liquid-liquid phase separation (LLPS), in response to external stimuli. YBX1, an integral component of SGs, plays a crucial role in tumor progression and cellular stress response. This study aims to elucidate the mechanisms and specific biological implications of YBX1 in SG formation, along with the identification of key regions and interacting proteins. Our observations indicate that YBX1 rapidly undergoes liquid-liquid phase separation, leading to SG formation in response to 8 Gy X-ray irradiation within 1 h, with SGs reverting to their original state after 5 h. There was a potential interaction between ATXN2L and YBX1, persisting YBX1 within the SGs. Our data suggested a potential interaction between ATXN2L and YBX1, and it remained associated with YBX1 within the SGs. Furthermore, our subsequent studies demonstrate that targeting ATXN2L can diminish the recruitment of YBX1 to stress granules (SGs), consequently enhancing the radiosensitivity of HeLa cells.</p>","PeriodicalId":20903,"journal":{"name":"Radiation research","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139521758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Radiation-induced Bystander Effects on Glioblastoma Tumor Cells via NMDA Receptor Signaling. 辐射通过 NMDA 受体信号对胶质母细胞瘤肿瘤细胞产生的旁观者效应
IF 2.5 3区 医学
Radiation research Pub Date : 2024-03-01 DOI: 10.1667/RADE-23-00166.1
Ying-Chun Lin, Jiamin Mo, Hanyan Zeng, Yuan-Hao Lee
{"title":"Radiation-induced Bystander Effects on Glioblastoma Tumor Cells via NMDA Receptor Signaling.","authors":"Ying-Chun Lin, Jiamin Mo, Hanyan Zeng, Yuan-Hao Lee","doi":"10.1667/RADE-23-00166.1","DOIUrl":"10.1667/RADE-23-00166.1","url":null,"abstract":"<p><p>Proton therapy has been widely applied on treating inaccessible and inoperable tumors, such as tumors deep within the brain or close to the critical brain stem. Nevertheless, the damaging effect of radiation for central nervous system (CNS) tumors is difficult to be confined within the irradiated region and has led to decline of neurological function in especially children with congenital CNS tumors. Currently, the involvement of n-methyl-d-aspartate (NMDA) receptors or secretary cytokines and chemokines in proton-induced bystander effects remains unclear. To understand the modulatory effects of NMDA receptor inhibition on the survival and proliferation of glioblastoma-derived cells, mesenchymal-like U373 cells were applied along with U87 neural glioblastoma cells for single doses of proton radiation at different LET in the presence or absence of pretreatment with memantine and/or collimation. Under collimation, neuronal tumor cells that are not directly irradiated (i.e., bystander cells) encounter similar biological effects potentially through cell coupling and synaptic transmission. Furthermore, whether proton LET plays a role in the mediation of bystander effect awaits to be elucidated. From this study, synaptic transmission was found to play differential roles in the proliferation of U373 and U87 cells after exposure to collimated radiation. Also, radiation-induced cell proliferation at the late stage was more correlated with bystander cell survival than early manifested γH2AX foci, suggesting that proton-induced glutamatergic synapse may act as a more important contributor than proton-induced direct effect on DNA double-stranded breaks to the late-stage responses of glioblastoma cells.</p>","PeriodicalId":20903,"journal":{"name":"Radiation research","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139642845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Fludarabine Enhances Radiosensitivity by Promoting Ferroptosis in B-Cell Lymphoma. 氟达拉滨通过促进B细胞淋巴瘤中的铁突变增强放射敏感性
IF 2.5 3区 医学
Radiation research Pub Date : 2024-03-01 DOI: 10.1667/RADE-23-00018.1
Qingqin Long, Huimin Tao, Peipei Wang, Biwen Wu, Qinghong Zhu, Hongwen Chen, Gang Lao, Yu Yang, Guolong Liu, Sihong Liu, Yong Wu
{"title":"Fludarabine Enhances Radiosensitivity by Promoting Ferroptosis in B-Cell Lymphoma.","authors":"Qingqin Long, Huimin Tao, Peipei Wang, Biwen Wu, Qinghong Zhu, Hongwen Chen, Gang Lao, Yu Yang, Guolong Liu, Sihong Liu, Yong Wu","doi":"10.1667/RADE-23-00018.1","DOIUrl":"10.1667/RADE-23-00018.1","url":null,"abstract":"<p><p>The objective of this study is to investigate the impact of fludarabine, a signal transducer and activator of transcription-1 (STAT1) inhibitor, on the radiosensitivity of B-cell lymphoma (BCL) and to explore the underlying mechanisms. Radiotherapy is one of the primary treatments for BCL, and STAT1 plays a critical role in the transcription of cell proliferation-related genes, which are associated with radiotherapy and ferroptosis. This study aims to determine whether fludarabine can enhance the radiosensitivity of BCL and to elucidate the molecular pathways involved. Various in vitro methodologies, including CCK-8 assays, clonogenic formation assays, immunohistochemistry, immunofluorescence, flow cytometry, qRT-PCR, and Western blot analyses, were employed in B-cell lymphoma cell models to thoroughly investigate the effects of fludarabine on radiosensitivity. Subsequently, the obtained results were further validated through in vivo animal models and by examining human diffuse large B-cell lymphoma (DLBCL) cancer samples. Our findings demonstrate that the combination of fludarabine and irradiation synergistically inhibits cell viability and colony formation, while inducing apoptosis and ferroptosis in B-cell lymphoma cell lines Raji and Su-DHL-10. Moreover, fludarabine was found to enhance the ferroptosis induced by radiation, thereby synergistically impeding the growth of BCL. In vivo experiments confirmed these findings, revealing that the intraperitoneal injection of fludarabine significantly enhanced the inhibitory effects of radiation on Raji cell xenograft models, leading to an increased percentage of ferroptosis compared to models without fludarabine. Additionally, the administration of liproxstatin-1, a ferroptosis inhibitor, attenuated the inhibition of xenograft growth caused by the combination of fludarabine and irradiation. Furthermore, our analysis of clinical data revealed that increased co-expression of STAT1 and GPX4 is associated with poor overall survival in patients with diffuse large B-cell lymphoma. These results highlight the potential of fludarabine to enhance radiosensitivity and ferroptosis induction as a promising therapeutic strategy for BCL. Our results demonstrated that fludarabine promoted radiation-induced BCL death through the ferroptosis pathway. We have identified a previously unrecognized mechanism in the fludarabine and radiation combination, indicating that it is necessary to conduct prospective clinical trials to verify this new treatment regimen in BCL.</p>","PeriodicalId":20903,"journal":{"name":"Radiation research","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139486276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
LET Dependence of 8-Hydroxy-2'-deoxyguanosine (8-OHdG) Generation in Mammalian Cells under Air-Saturated and Hypoxic Conditions: A Possible Experimental Approach to the Mechanism of the Decreasing Oxygen Effect in the High-LET Region. 空气饱和和缺氧条件下哺乳动物细胞中 8-羟基-2'-脱氧鸟苷(8-OHdG)生成的 LET 依赖性:高 LET 区氧气效应递减机制的可能实验方法。
IF 2.5 3区 医学
Radiation research Pub Date : 2024-03-01 DOI: 10.1667/RADE-23-00046.1
A Ito, S Kitabatake, W Furuichi, N Takase, T Nakahara, T Akiyama, S Yoshida, Y Kusano, Y Furusawa, R Hirayama
{"title":"LET Dependence of 8-Hydroxy-2'-deoxyguanosine (8-OHdG) Generation in Mammalian Cells under Air-Saturated and Hypoxic Conditions: A Possible Experimental Approach to the Mechanism of the Decreasing Oxygen Effect in the High-LET Region.","authors":"A Ito, S Kitabatake, W Furuichi, N Takase, T Nakahara, T Akiyama, S Yoshida, Y Kusano, Y Furusawa, R Hirayama","doi":"10.1667/RADE-23-00046.1","DOIUrl":"10.1667/RADE-23-00046.1","url":null,"abstract":"<p><p>One of the most distinguished features in biological effects of heavy ions would be the decrease of oxygen effect in the high-LET region. This feature has been referred to as the radiobiological basis for the control of hypoxic fraction in cancer radiotherapy. However, mechanisms to explain this phenomenon have not been fully understood. One of the explanations was given by the oxygen in the track hypothesis, which proposes that oxygen is produced along ion tracks even in the hypoxic irradiation condition. In the present study, we designed an experimental approach to support this hypothesis by using 8-hydroxy-2'-deoxyguanosine (8-OHdG) as DNA damage requiring oxygen to produce. The LET dependence of 8-OHdG under hypoxic condition revealed that with increasing LET 8-OHdG yield seems to increase, despite that the yield of OH radical, which is also required for the production of 8-OHdG, decreases in the high-LET region. This result is consistent with the explanation that the local generation of oxygen along ion tracks contributes to the increase of 8-OHdG yield.</p>","PeriodicalId":20903,"journal":{"name":"Radiation research","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139642844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
TDP-43 was Involved in Radiation-induced Neuronal Damage and May Not Through the BDNF/TrkB Pathway. TDP-43 参与了辐射诱导的神经元损伤,但可能不是通过 BDNF/TrkB 途径。
IF 2.5 3区 医学
Radiation research Pub Date : 2024-03-01 DOI: 10.1667/RADE-23-00168.1
Rui Sun, Kedi Xi, Shengjun Ji, Xing Song, Dan Xi, Wenming Yin, Yingjie Shao, Wendong Gu, Jingting Jiang
{"title":"TDP-43 was Involved in Radiation-induced Neuronal Damage and May Not Through the BDNF/TrkB Pathway.","authors":"Rui Sun, Kedi Xi, Shengjun Ji, Xing Song, Dan Xi, Wenming Yin, Yingjie Shao, Wendong Gu, Jingting Jiang","doi":"10.1667/RADE-23-00168.1","DOIUrl":"10.1667/RADE-23-00168.1","url":null,"abstract":"<p><p>Cognitive dysfunction is the most common form of radiation-induced brain injury. TDP-43 is known to be associated with hippocampal degeneration and cognitive dysfunction, in this study we wanted to know if it also had an effect on radiation-induced hippocampus damage. At first, we found the expression of TDP-43 and p-TDP-43 was increased in the hippocampus of rats with radiation-induced cognitive dysfunction. Single-cell RNA-seq analysis of the rat hippocampus showed that TDP-43 was expressed in all cell types and was significantly upregulated in neuron cells after irradiation. Enrichment analysis of gene ontology (GO) functions and KEGG pathways showed that the differential expression genes in neuron after irradiation may be involved in synaptic plasticity. In vitro, the expression of TDP-43 was also increased in neuron cells after irradiation, while the expression of brain-derived neurotrophic factor (BDNF), TrkB, typical synaptic signature proteins (SYN, GAP43 and PSD95), β-tubulin and dendritic spines were decreased. In the irradiated neurons, the β-tubulin, dendritic and spines typical synaptic signature proteins had more severe damage in pcDNA3.1-TDP-43 plasmid transfections group, however, the damages were alleviated in the siRNA-TDP-43 plasmid transfections group. BDNF was highly expressed in the irradiated pcDNA3.1-TDP-43 plasmid transfections group, while its expression was decreased in the siRNA-TDP-43 group. The TrkB expression was significantly reduced in neurons after exposure to ionizing radiation, however, there was no significant correlation with TDP-43 expression. These data indicate that TDP-43 is involved in radiation-induced neuronal synaptic plasticity decline and developmental damage, furthermore, the BDNF/TrkB signaling pathway may not be involved in this process.</p>","PeriodicalId":20903,"journal":{"name":"Radiation research","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139486277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Reconfiguring a Plane-Parallel Transmission Ionization Chamber to Extend the Operating Range into the Ultra-High Dose-per-pulse Regime. 重新配置平面平行传输电离室,将工作范围扩展到每脉冲超高剂量区。
IF 2.5 3区 医学
Radiation research Pub Date : 2024-03-01 DOI: 10.1667/RADE-23-00177.1
Elise Konradsson, Rebecka Ericsson Szecsenyi, Pontus Wahlqvist, Andreas Thoft, Börje Blad, Sven Åj Bäck, Crister Ceberg, Kristoffer Petersson
{"title":"Reconfiguring a Plane-Parallel Transmission Ionization Chamber to Extend the Operating Range into the Ultra-High Dose-per-pulse Regime.","authors":"Elise Konradsson, Rebecka Ericsson Szecsenyi, Pontus Wahlqvist, Andreas Thoft, Börje Blad, Sven Åj Bäck, Crister Ceberg, Kristoffer Petersson","doi":"10.1667/RADE-23-00177.1","DOIUrl":"10.1667/RADE-23-00177.1","url":null,"abstract":"<p><p>This study aims to investigate the feasibility of enhancing the charge collection efficiency (CCE) of a transmission chamber by reconfiguring its design and operation. The goal was to extend the range of dose-per-pulse (DPP) values with no or minimal recombination effects up to the ultra-high dose rate (UHDR) regime. The response of two transmission chambers, with electrode distance of 1 mm and 0.6 mm, respectively, was investigated as a function of applied voltage. The chambers were mounted one-by-one in the electron applicator of a 10 MeV FLASH-modified clinical linear accelerator. The chamber signals were measured as a function of nominal DPP, which was determined at the depth of dose maximum using EBT-XD film in solid water and ranged from 0.6 mGy per pulse to 0.9 Gy per pulse, for both the standard voltage of 320 V and the highest possible safe voltage of 1,200 V. The CCE was calculated and fitted with an empirical logistic function that incorporated the electrode distance and the chamber voltage. The CCE decreased with increased DPP. The CCE at the highest achievable DPP was 24% (36%) at 320 V and 51% (82%) at 1,200 V, for chambers with 1 mm (0.6 mm) electrode distance. For the combination of 1,200 V- and 0.6-mm electrode distance, the CCE was ∼100% for average dose rate up to 70 Gy/s at the depth of dose maximum in the phantom at a source-to-surface distance of 100 cm. Our findings indicate that minor modifications to a plane-parallel transmission chamber can substantially enhance the CCE and extending the chamber's operating range to the UHDR regime. This supports the potential of using transmission chamber-based monitoring solutions for UHDR beams, which could facilitate the delivery of UHDR treatments using an approach similar to conventional clinical delivery.</p>","PeriodicalId":20903,"journal":{"name":"Radiation research","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139672540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Finite-Sample Bias of the Linear Excess Relative Risk in Cohort Studies of Computed Tomography-Related Radiation Exposure and Cancer. 计算机断层扫描相关辐射暴露与癌症队列研究中线性超额相对风险的有限样本偏差。
IF 2.5 3区 医学
Radiation research Pub Date : 2024-03-01 DOI: 10.1667/RADE-23-00187.1
L Caramenti, P L Gradowska, D Moriña, G Byrnes, E Cardis, M Hauptmann
{"title":"Finite-Sample Bias of the Linear Excess Relative Risk in Cohort Studies of Computed Tomography-Related Radiation Exposure and Cancer.","authors":"L Caramenti, P L Gradowska, D Moriña, G Byrnes, E Cardis, M Hauptmann","doi":"10.1667/RADE-23-00187.1","DOIUrl":"10.1667/RADE-23-00187.1","url":null,"abstract":"<p><p>The linear excess relative risk (ERR) is the most commonly reported measure of association in radiation epidemiological studies, when individual dose estimates are available. While the asymptotic properties of the ERR estimator are well understood, there is evidence of small sample bias in case-control studies of treatment-related radiation exposure and second cancer risk. Cohort studies of cancer risk after exposure to low doses of radiation from diagnostic procedures, e.g., computed tomography (CT) examinations, typically have small numbers of cases and risks are small. Therefore, understanding the properties of the estimated ERR is essential for interpretation and analysis of such studies. We present results of a simulation study that evaluates the finite-sample bias of the ERR estimated by time-to-event analyses and its confidence interval using simulated data, resembling a retrospective cohort study of radiation-related leukemia risk after CT examinations in childhood and adolescence. Furthermore, we evaluate how the Firth-corrected estimator reduces the finite-sample bias of the classical estimator. We show that the ERR is overestimated by about 30% for a cohort of about 150,000 individuals, with 42 leukemia cases observed on average. The bias is reduced for higher baseline incidence rates and for higher values of the true ERR. As the number of cases increases, the ERR is approximately unbiased. The Firth correction reduces the bias for all cohort sizes to generally around or under 5%. Epidemiological studies showing an association between radiation exposure from pediatric CT and cancer risk, unless very large, may overestimate the magnitude of the relationship, while there is no evidence of an increased chance for false-positive results. Conducting large studies, perhaps by pooling individual studies to increase the number of cases, should be a priority. If this is not possible, Firth correction should be applied to reduce small-sample bias.</p>","PeriodicalId":20903,"journal":{"name":"Radiation research","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139698141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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