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Robust optimization incorporating weekly predicted anatomical CTs in IMPT of nasopharyngeal cancer. 将每周预测的解剖 CT 纳入鼻咽癌 IMPT 的稳健优化。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-10-28 DOI: 10.1088/1361-6560/ad8859
Mark Ka Heng Chan, Ying Zhang

Objective.This study proposes a robust optimization (RO) strategy utilizing virtual CTs (vCTs) predicted by an anatomical model in intensity-modulated proton therapy (IMPT) for nasopharyngeal cancer (NPC).Methods and Materials.For ten NPC patients, vCTs capturing anatomical changes at different treatment weeks were generated using a population average anatomy model. Two RO strategies of a 6 beams IMPT with 3 mm setup uncertainty (SU) and 3% range uncertainty (RU) were compared: conventional robust optimization (cRO) based on a single planning CT (pCT), and anatomical RO incorporating 2 and 3 predicted anatomies (aRO2 and aRO3). The robustness of these plans was assessed by recalculating them on weekly CTs (week 2-7) and extracting the voxel wise-minimum and maximum doses with 1 mm SU and 3% RU (voxminvoxmax1mm3%).Results.The aRO plans demonstrated improved robustness in high-risk CTV1 and low-risk CTV 2 coverage compared to cRO plans. The weekly evaluation showed a lower plan adaptation rate for aRO3 (40%) vs. cRO (70%). The weekly nominal and voxmax1mm3%doses to OARs, especially spinal cord, are better controlled relative to their baseline doses at week 1 with aRO plans. The accumulated dose analysis showed that CTV1&2 had adequate coverage and serial organs (spinal cord and brainstem) were within their dose tolerances in the voxminvoxmax1mm3%, respectively.Conclusion.Incorporating predicted weekly CTs from a population based average anatomy model in RO improves week-to-week target dose coverage and reduces false plan adaptations without increasing normal tissue doses. This approach enhances IMPT plan robustness, potentially facilitating reduced SU and further lowering OAR doses.

目的: 本研究提出了一种稳健优化(RO)策略,利用解剖模型预测的虚拟 CT(vCT)进行鼻咽癌(NPC)的强度调制质子治疗(IMPT) 方法和材料: 使用群体平均解剖模型,为 10 名鼻咽癌患者生成了捕捉不同治疗周解剖变化的 vCT。比较了具有 3 毫米设置不确定性 (SU) 和 3% 范围不确定性 (RU) 的 6 束 IMPT 的两种稳健优化策略:基于单个规划 CT (pCT) 的传统稳健优化 (cRO) 和包含 2 和 3 个预测解剖结构的解剖稳健优化 (aRO2 和 aRO3)。通过在每周 CT(第 2 至第 7 周)上重新计算这些计划,并提取 1mm SU 和 3% RU 的体素明智最小剂量和最大剂量(voxmin-max1mm3%),来评估这些计划的稳健性。每周评估显示,aRO3(40%)与 cRO(70%)相比,计划适应率较低;采用 aRO 计划后,OAR(尤其是脊髓)的每周名义剂量和 voxmax1mm3% 剂量与第 1 周的基线剂量相比得到了更好的控制。累积剂量分析表明,CTV1 和 2 有足够的覆盖范围,序列器官(脊髓和脑干)的 voxmin-/max1mm3% 分别在其剂量容许范围内。这种方法增强了IMPT计划的稳健性,可能有助于减少设置的不确定性,进一步降低OAR剂量。
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引用次数: 0
Study on the impact of bowtie filter on photon-counting CT imaging. 弓形滤波器对光子计数 CT 成像影响的研究
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-10-28 DOI: 10.1088/1361-6560/ad8858
Xin Zhang, Jixiong Xie, Ting Su, Jiongtao Zhu, Dongmei Xia, Hairong Zheng, Dong Liang, Yongshuai Ge

Objective.The aim of this study was to investigate the impact of the bowtie filter on the image quality of the photon-counting detector (PCD) based CT imaging.Approach.Numerical simulations were conducted to investigate the impact of bowtie filters on image uniformity using two water phantoms, with tube potentials ranging from 60 to 140 kVp with a step of 5 kVp. Subsequently, benchtop PCD-CT imaging experiments were performed to verify the observations from the numerical simulations. Additionally, various correction methods were validated through these experiments.Main results.It was found that the use of a bowtie filter significantly alters the uniformity of PCD-CT images, depending on the size of the object and the x-ray spectrum. Two notable effects were observed: the capping effect and the flattening effect. Furthermore, it was demonstrated that the conventional beam hardening correction method could effectively mitigate such non-uniformity in PCD-CT images, provided that dedicated calibration parameters were used.Significance.It was demonstrated that the incorporation of a bowtie filter results in varied image artifacts in PCD-CT imaging under different conditions. Certain image correction methods can effectively mitigate and reduce these artifacts, thereby enhancing the overall quality of PCD-CT images.

研究目的本研究旨在探讨弓形滤波器对基于光子计数探测器(PCD)的 CT 成像质量的影响:使用两个水模型进行数值模拟,研究弓形滤波器对图像均匀性的影响,管电势范围为 60 到 140 kVp,步幅为 5 kVp。随后,进行了台式 PCD-CT 成像实验,以验证数值模拟的观察结果。此外,还通过这些实验验证了各种校正方法:研究发现,使用弓形滤光片会显著改变 PCD-CT 图像的均匀性,这取决于物体的大小和 X 射线光谱。观察到两种明显的效应:封盖效应和扁平效应。此外,研究还证明,只要使用专用的校准参数,传统的光束硬化校正方法就能有效缓解 PCD-CT 图像中的这种不均匀性:研究表明,在不同条件下,加入弓形滤波器会导致 PCD-CT 成像出现不同的图像伪影。某些图像校正方法可以有效缓解和减少这些伪影,从而提高 PCD-CT 图像的整体质量。
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引用次数: 0
Initial results of the Hyperion IIDPET insert for simultaneous PET-MRI applied to atherosclerotic plaque imaging in New-Zealand white rabbits. 应用于新西兰白兔动脉粥样硬化斑块成像的同步 PET-MRI Hyperion IIDPET 插件的初步结果。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-10-28 DOI: 10.1088/1361-6560/ad8c1f
Pierre Gebhardt, Begona Lavin, Alkystis Phinikaridou, Jane E Mackewn, Markus Henningsson, David Schug, Andre Salomon, Paul K Marsden, Volkmar Schulz, René Botnar

Objective: In preclinical research, in vivo imaging of mice and rats is more common than any other animal species, since their physiopathology is very well- known and many genetically altered disease models exist. Animal studies based on small rodents are usually performed using dedicated preclinical imaging systems with high spatial resolution. For studies that require animal models such as mini- pigs or New-Zealand White (NZW) rabbits, imaging systems with larger bore sizes are required. In case of hybrid imaging using Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI), clinical systems have to be used, as these animal models do not typically fi t in preclinical simultaneous PET-MRI scanners. Approach. In this paper, we present initial imaging results obtained with the Hyperion IID PET insert which can accommodate NZW rabbits when combined with a large volume MRI RF coil. First, we developed a rabbit-sized image quality phantom of comparable size to a NZW rabbit in order to evaluate the PET imaging performance of the insert under high count rates. For this phantom, radioactive spheres with inner diameters between 3.95 and 7.86 mm were visible in a warm background with a tracer activity ratio of 4.1 to 1 and with a total 18-F activity in the phantom of 58MBq at measurement start. Second, we performed simultaneous PET-MR imaging of atherosclerotic plaques in a rabbit in vivo using a single injection containing 18-F-FDG for detection of infl ammatory activity, and Gd-ESMA for visualization of the aortic vessel wall and plaques with MRI. Main results. The fused PET-MR images reveal 18-F-FDG uptake within an active plaques with plaque thicknesses in the sub-millimeter range. Histology showed colocalization of 18-F-FDG uptake with macrophages in the aortic vessel wall lesions. Significance. Our initial results demonstrate that this PET insert is a promising system for simultaneous high-resolution PET-MR atherosclerotic plaque imaging studies in NZW rabbits.

目的:在临床前研究中,小鼠和大鼠的体内成像比任何其他动物物种都更为常见,因为它们的生理病理非常清楚,而且存在许多基因改变的疾病模型。基于小型啮齿动物的动物研究通常使用具有高空间分辨率的专用临床前成像系统 进行。对于需要使用小型猪或新西兰白(NZW)兔等动物模型的研究,则需要使用孔径更大的成像系统。如果使用正电子发射断层扫描(PET)和磁共振成像(MRI)进行混合成像,则必须使用临床系统,因为这些动物模型通常无法使用临床前同步 PET-MRI 扫描仪。在本文中,我们介绍了使用 Hyperion IID PET 插片获得的初步成像结果,该插片与大体积 MRI 射频线圈结合使用时,可容纳 NZW 兔子。首先,我们开发了一个与 NZW 兔子大小相当的兔子大小的图像 质量模型,以评估该插件在高计数率下的 PET 成像性能。在该模型中,内径介于 3.95 毫米和 7.86 毫米之间的放射性球体在温暖的背景中清晰可见,示踪剂活度比为 4.1:1,测量开始时模型中的 18-F 总活度为 58MBq。其次,我们对兔子体内的动脉粥样硬化斑块进行了同步 PET-MR 成像,使用 18-F-FDG 单次注射检测动脉粥样硬化活动,并使用 Gd-ESMA 通过 MRI 观察主动脉血管壁和斑块。融合 PET-MR 图像显示活动斑块内摄取了 18-F-FDG,斑块厚度在亚毫米范围内。组织学 显示 18-F-FDG 摄取与主动脉血管壁病变中的巨噬细胞共定位。我们的初步研究结果表明,这种 PET 插入物 是在 NZW 兔子中同时进行高分辨率 PET-MR 动脉粥样硬化斑块成像研究的理想系统。
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引用次数: 0
Assessing suitability and stability of materials for a head and neck anthropomorphic multimodality (MRI/CT) phantoms for radiotherapy. 评估用于放射治疗的头颈部拟人多模态(MRI/CT)模型材料的适用性和稳定性。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-10-28 DOI: 10.1088/1361-6560/ad8830
Meshal Alzahrani, David A Broadbent, Irvin Teh, Bashar Al-Qaisieh, Richard Speight

Objective:This study aims to identify and evaluate suitable and stable materials for developing a head and neck anthropomorphic multimodality phantom for radiotherapy purposes. These materials must mimic human head and neck tissues in both computed tomography (CT) and magnetic resonance imaging (MRI) and maintain stable imaging properties over time and after radiation exposure, including the high levels associated with linear accelerator (linac) use.Approach:Various materials were assessed by measuring their CT numbers and T1 and T2 relaxation times. These measurements were compared to literature values to determine how closely the properties of the candidate materials resemble those of human tissues in the head and neck region. The stability of these properties was evaluated monthly over a year and after radiation exposure to doses up to 1000 Gy. Statistical analyzes were conducted to identify any significant changes over time and after radiation exposure.Main results:10% and 12.6% Polyvinyl alcohol cryogel (PVA-c) both exhibited T1 and T2 relaxation times and CT numbers within the range appropriate for brain grey matter. 14.3% PVA-c and some plastic-based materials matched the MRI properties of brain white matter, with CT numbers close to the clinical range. Additionally, some plastic-based materials showed T1 and T2 relaxation times consistent with MRI properties of fat, although their CT numbers were not suitable. Over time and after irradiation, 10% PVA-c maintained consistent properties for brain grey matter. 12.6% PVA-c's T1 relaxation time decreased beyond the range after the first month.Significance:This study identified 10% PVA-c as a substitute for brain grey matter, demonstrating stable imaging properties over a year and after radiation exposure up to 1000 Gy. However, the results highlight a need for further research to find additional materials to accurately simulate a wider range of human tissues.

目的: 本研究旨在确定和评估合适且稳定的材料,以开发用于放射治疗的头颈部拟人多模态模型。这些材料必须在计算机断层扫描(CT)和磁共振成像(MRI)中模拟人体头颈部组织,并在长时间的辐射照射(包括使用直线加速器(linac)时产生的高水平辐射)后保持稳定的成像特性。将这些测量值与文献值进行比较,以确定候选材料的特性与头颈部人体组织的特性有多接近。在一年的时间里,每月对这些特性的稳定性进行评估,并在接受剂量高达 1000 Gy 的辐射照射后进行评估。主要结果: 10% 和 12.6% 聚乙烯醇冷冻凝胶 (PVA-c) 的 T1 和 T2 弛豫时间和 CT 数值都在适合大脑灰质的范围内。14.3% 的 PVA-c 和一些塑料基材料符合脑白质的磁共振成像特性,CT 值接近临床范围。此外,一些塑料基材料显示的 T1 和 T2 驰豫时间与脂肪的磁共振成像特性一致,尽管它们的 CT 数值并不合适。随着时间的推移和照射后,10% PVA-c 对大脑灰质的特性保持一致。12.6%PVA-c的T1弛豫时间在第一个月后下降,超出了规定范围。不过,研究结果强调了进一步研究的必要性,以便找到更多材料来精确模拟更广泛的人体组织。
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引用次数: 0
Optimisation of cone beam CT radiotherapy imaging protocols using a novel 3D printed head and neck anthropomorphic phantom. 使用新型 3D 打印头颈部拟人模型优化锥形束 CT 放射治疗成像方案。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-10-28 DOI: 10.1088/1361-6560/ad88d2
Meshal Alzahrani, Christopher O'Hara, David Bird, Jack P C Baldwin, Mitchell Naisbit, Irvin Teh, David A Broadbent, Bashar Al-Qaisieh, Emily Johnstone, Richard Speight

Objective.This study aimed to optimise Cone Beam Computed Tomography (CBCT) protocols for head and neck (H&N) radiotherapy treatments using a 3D printed anthropomorphic phantom. It focused on precise patient positioning in conventional treatment and adaptive radiotherapy (ART).Approach.Ten CBCT protocols were evaluated with the 3D-printed H&N anthropomorphic phantom, including one baseline protocol currently used at our centre and nine new protocols. Adjustments were made to milliamperage and exposure time to explore their impact on radiation dose and image quality. Additionally, the effect on image quality of varying the scatter correction parameter for each of the protocols was assessed. Each protocol was compared against a reference CT scan. Usability was assessed by three Clinical Scientists using a Likert scale, and statistical validation was performed on the findings.Main results. The work revealed variability in the effectiveness of protocols. Protocols optimised for lower radiation exposure maintained sufficient image quality for patient setup in a conventional radiotherapy pathway, suggesting the potential for reducing patient radiation dose by over 50% without compromising efficacy. Optimising ART protocols involves balancing accuracy across brain, bone, and soft tissue, as no single protocol or scatter correction parameter achieves optimal results for all simultaneously.Significance.This study underscores the importance of optimising CBCT protocols in H&N radiotherapy. Our findings highlight the potential to maintain the usability of CBCT for bony registration in patient setup while significantly reducing the radiation dose, emphasizing the significance of optimising imaging protocols for the task in hand (registering to soft tissue or bone) and aligning with the as low as reasonably achievable principle. More studies are needed to assess these protocols for ART, including CBCT dose measurements and CT comparisons. Furthermore, the novel 3D printed anthropomorphic phantom demonstrated to be a useful tool when optimising CBCT protocols.

目的: 本研究旨在使用 3D 打印的拟人化模型优化头颈部 (H&N) 放射治疗的锥形束计算机断层扫描 (CBCT) 方案。方法: 使用 3D 打印的 H&N 拟人模型评估了十种 CBCT 方案,包括我们中心目前使用的一种基准方案和九种新方案。对毫安培数和曝光时间进行了调整,以探讨它们对辐射剂量和图像质量的影响。此外,还评估了改变每个方案的散射校正参数对图像质量的影响。每个方案都与参考 CT 扫描进行了比较。由三位临床科学家使用李克特量表对可用性进行评估,并对评估结果进行统计验证。为降低辐射量而优化的方案在传统放疗路径中保持了足够的图像质量,这表明在不影响疗效的情况下,有可能将患者的辐射剂量减少 50%以上。优化 ART 方案需要平衡脑、骨和软组织的精确度,因为没有一种方案或散射校正参数能同时达到所有方案的最佳效果。我们的研究结果突显了在患者设置中保持 CBCT 用于骨骼登记的可用性,同时大幅降低辐射剂量的潜力,强调了针对手头任务(登记到软组织或骨骼)优化成像方案的重要性,并符合 "尽可能低"(ALARA)的原则。需要进行更多的研究来评估这些 ART 方案,包括 CBCT 剂量测量和 CT 对比。此外,在优化 CBCT 方案时,新颖的 3D 打印拟人模型被证明是一种有用的工具。
{"title":"Optimisation of cone beam CT radiotherapy imaging protocols using a novel 3D printed head and neck anthropomorphic phantom.","authors":"Meshal Alzahrani, Christopher O'Hara, David Bird, Jack P C Baldwin, Mitchell Naisbit, Irvin Teh, David A Broadbent, Bashar Al-Qaisieh, Emily Johnstone, Richard Speight","doi":"10.1088/1361-6560/ad88d2","DOIUrl":"10.1088/1361-6560/ad88d2","url":null,"abstract":"<p><p><i>Objective.</i>This study aimed to optimise Cone Beam Computed Tomography (CBCT) protocols for head and neck (H&N) radiotherapy treatments using a 3D printed anthropomorphic phantom. It focused on precise patient positioning in conventional treatment and adaptive radiotherapy (ART).<i>Approach.</i>Ten CBCT protocols were evaluated with the 3D-printed H&N anthropomorphic phantom, including one baseline protocol currently used at our centre and nine new protocols. Adjustments were made to milliamperage and exposure time to explore their impact on radiation dose and image quality. Additionally, the effect on image quality of varying the scatter correction parameter for each of the protocols was assessed. Each protocol was compared against a reference CT scan. Usability was assessed by three Clinical Scientists using a Likert scale, and statistical validation was performed on the findings.<i>Main results</i>. The work revealed variability in the effectiveness of protocols. Protocols optimised for lower radiation exposure maintained sufficient image quality for patient setup in a conventional radiotherapy pathway, suggesting the potential for reducing patient radiation dose by over 50% without compromising efficacy. Optimising ART protocols involves balancing accuracy across brain, bone, and soft tissue, as no single protocol or scatter correction parameter achieves optimal results for all simultaneously.<i>Significance.</i>This study underscores the importance of optimising CBCT protocols in H&N radiotherapy. Our findings highlight the potential to maintain the usability of CBCT for bony registration in patient setup while significantly reducing the radiation dose, emphasizing the significance of optimising imaging protocols for the task in hand (registering to soft tissue or bone) and aligning with the as low as reasonably achievable principle. More studies are needed to assess these protocols for ART, including CBCT dose measurements and CT comparisons. Furthermore, the novel 3D printed anthropomorphic phantom demonstrated to be a useful tool when optimising CBCT protocols.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142472542","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
Deep learning-based automatic contour quality assurance for auto-segmented abdominal MR-Linac contours. 基于深度学习的自动轮廓质量保证,用于自动分割腹部 MR-Linac 轮廓。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-10-25 DOI: 10.1088/1361-6560/ad87a6
Mohammad Zarenia, Ying Zhang, Christina Sarosiek, Renae Conlin, Asma Amjad, Eric Paulson

Objective.Deep-learning auto-segmentation (DLAS) aims to streamline contouring in clinical settings. Nevertheless, achieving clinical acceptance of DLAS remains a hurdle in abdominal MRI, hindering the implementation of efficient clinical workflows for MR-guided online adaptive radiotherapy (MRgOART). Integrating automated contour quality assurance (ACQA) with automatic contour correction (ACC) techniques could optimize the performance of ACC by concentrating on inaccurate contours. Furthermore, ACQA can facilitate the contour selection process from various DLAS tools and/or deformable contour propagation from a prior treatment session. Here, we present the performance of novel DL-based 3D ACQA models for evaluating DLAS contours acquired during MRgOART.Approach.The ACQA model, based on a 3D convolutional neural network (CNN), was trained using pancreas and duodenum contours obtained from a research DLAS tool on abdominal MRIs acquired from a 1.5 T MR-Linac. The training dataset contained abdominal MR images, DL contours, and their corresponding quality ratings, from 103 datasets. The quality of DLAS contours was determined using an in-house contour classification tool, which categorizes contours as acceptable or edit-required based on the expected editing effort. The performance of the 3D ACQA model was evaluated using an independent dataset of 34 abdominal MRIs, utilizing confusion matrices for true and predicted classes.Main results.The ACQA predicted 'acceptable' and 'edit-required' contours at 72.2% (91/126) and 83.6% (726/868) accuracy for pancreas, and at 71.2% (79/111) and 89.6% (772/862) for duodenum contours, respectively. The model successfully identified false positive (extra) and false negative (missing) DLAS contours at 93.75% (15/16) and %99.7 (438/439) accuracy for pancreas, and at 95% (57/60) and 98.9% (91/99) for duodenum, respectively.Significance.We developed 3D-ACQA models capable of quickly evaluating the quality of DLAS pancreas and duodenum contours on abdominal MRI. These models can be integrated into clinical workflow, facilitating efficient and consistent contour evaluation process in MRgOART for abdominal malignancies.

目的深度学习自动分割(DLAS)旨在简化临床环境中的轮廓划分。然而,在腹部磁共振成像中,DLAS 的临床接受度仍是一个障碍,阻碍了磁共振引导下在线自适应放射治疗(MRgOART)高效临床工作流程的实施。将自动轮廓质量保证(ACQA)与自动轮廓校正(ACC)技术相结合,可以集中处理不准确的轮廓,从而优化 ACC 的性能。此外,ACQA 还能促进从各种 DLAS 工具和/或之前治疗过程中的可变形轮廓传播中选择轮廓的过程。在此,我们介绍了基于 DL 的新型 3D ACQA 模型的性能,用于评估在 MRgOART 期间获取的 DLAS 轮廓。ACQA 模型基于三维卷积神经网络 (CNN),使用研究 DLAS 工具在 1.5T MR-Linac 采集的腹部 MRI 上获得的胰腺和十二指肠轮廓进行训练。训练数据集包含来自 103 个数据集的腹部 MR 图像、DL 轮廓及其相应的质量评级。DLAS 轮廓的质量是通过内部的轮廓分类工具确定的,该工具根据预期的编辑工作量将轮廓分为可接受的和需要编辑的。利用真实和预测类别的混淆矩阵,使用 34 个腹部 MRI 的独立数据集评估了 3D ACQA 模型的性能。ACQA 预测胰腺轮廓 "可接受 "和 "需要编辑 "的准确率分别为 72.2%(91/136)和 83.6%(726/868),预测十二指肠轮廓的准确率分别为 71.2%(79/111)和 89.6%(772/862)。该模型成功识别了假阳性(额外)和假阴性(缺失)DLAS 轮廓,胰腺的准确率分别为 93.75% (15/16) 和 %99.7 (438/439),十二指肠的准确率分别为 95% (57/60) 和 98.9% (91/99)。我们开发的 3D-ACQA 模型能够快速评估腹部 MRI 上 DLAS 胰腺和十二指肠轮廓的质量。这些模型可集成到临床工作流程中,促进腹部恶性肿瘤 MRgOART 中高效、一致的轮廓评估过程。
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引用次数: 0
First test beam of the DMAPS-based proton tracker at the pMBRT facility at the Curie Institute. 居里研究所 pMBRT 设备上基于 DMAPS 的质子跟踪器的第一束试验光束。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-10-25 DOI: 10.1088/1361-6560/ad84b3
M Granado-González, T Price, L Gonella, K Moustakas, T Hirono, T Hemperek, L De Marzi, A Patriarca

Objective.Proton radiotherapy's efficacy relies on an accurate relative stopping power (RSP) map of the patient to optimise the treatment plan and minimize uncertainties. Currently, a conversion of a Hounsfield Units map obtained by a common x-ray computed tomography (CT) is used to compute the RSP. This conversion is one of the main limiting factors for proton radiotherapy. To bypass this conversion a direct RSP map could be obtained by performing a proton CT (pCT). The focal point of this article is to present a proof of concept of the potential of fast pixel technologies for proton tracking at clinical facilities.Approach.A two-layer tracker based on the TJ-Monopix1, a depleted monolithic active pixel sensor (DMAPS) chip initially designed for the ATLAS, was tested at the proton minibeam radiotherapy beamline at the Curie Institute. The chips were subjected to 100 MeV protons passing through the single slit collimator (0.4×20mm2) with fluxes up to1.3×107p s-1 cm-2. The performance of the proton tracker was evaluated with GEANT4 simulations.Main results.The beam profile and dispersion in air were characterized by an opening of 0.031 mm cm-1, and aσx=0.172mm at the position of the slit. The results of the proton tracking show how the TJ-Monopix1 chip can effectively track protons in a clinical environment, achieving a tracking purity close to 70%, and a position resolution below 0.5 mm; confirming the chip's ability to handle high proton fluxes with a competitive performance.Significance.This work suggests that DMAPS technologies can be a cost-effective alternative for proton imaging. Additionally, the study identifies areas where further optimization of chip design is required to fully leverage these technologies for clinical ion imaging applications.

textbf{Objective.}质子放疗的疗效有赖于精确的患者相对停止功率(RSP)图,以优化治疗方案并将不确定性降至最低。目前,通过普通X射线计算机断层扫描(CT)获得的霍斯菲尔德单位(HU)图转换用于计算RSP。这种转换是质子放疗的主要限制因素之一。为了绕过这种转换,可以通过质子 CT(pCT)直接获得 RSP 图。本文的重点是介绍快速像素技术在临床设施质子跟踪方面的潜力的概念验证。基于TJ-Monopix1(一种最初为ATLAS设计的贫化单片有源像素传感器(DMAPS)芯片)的双层跟踪器在居里研究所的质子迷你束射电治疗(pMBRT)光束线进行了测试。这些芯片经受了通过单缝准直器(0.4times$20 mm$^2$)的 100 MeV 质子的考验,通量高达 1.3 times 10^7$ p/s/cm$^2$。质子跟踪器的性能通过 GEANT4 仿真进行了评估。 textbf{主要结果:} 空气中的光束轮廓和弥散的特点是:开口为 0.031~mm/cm,狭缝位置的 $sigma_x=0.172$~mm。质子跟踪的结果表明,TJ-Monopix1 芯片可以在临床环境中有效地跟踪质子,跟踪纯度接近~70~$%$,位置分辨率低于 0.5 mm;证实了该芯片有能力处理高质子通量,且性能具有竞争力。这项研究表明,DMAPS 技术可以成为质子成像的一种经济有效的替代方案。此外,这项研究还确定了需要进一步优化芯片设计的领域,以便在临床离子成像应用中充分利用这些技术。
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引用次数: 0
Proton ARC based LATTICE radiation therapy: feasibility study, energy layer optimization and LET optimization. 基于质子 ARC 的 LATTICE 放射治疗:可行性研究、能量层优化和 LET 优化。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-10-25 DOI: 10.1088/1361-6560/ad8855
Ya-Nan Zhu, Weijie Zhang, Jufri Setianegara, Yuting Lin, Erik Traneus, Yong Long, Xiaoqun Zhang, Rajeev Badkul, David Akhavan, Fen Wang, Ronald C Chen, Hao Gao
<p><p><i>Objective.</i>LATTICE, a spatially fractionated radiation therapy (SFRT) modality, is a 3D generalization of GRID and delivers highly modulated peak-valley spatial dose distribution to tumor targets, characterized by peak-to-valley dose ratio (PVDR). Proton LATTICE is highly desirable, because of the potential synergy of the benefit from protons compared to photons, and the benefit from LATTICE compared to GRID. Proton LATTICE using standard proton RT via intensity modulated proton therapy (IMPT) (with a few beam angles) can be problematic with poor target dose coverage and high dose spill to organs-at-risk (OAR). This work will develop novel proton LATTICE method via proton ARC (with many beam angles) to overcome these challenges in target coverage and OAR sparing, with optimized delivery efficiency via energy layer optimization and optimized biological dose distribution via linear energy transfer (LET) optimization, to enable the clinical use of proton LATTICE.<i>Approach.</i>ARC based proton LATTICE is formulated and solved with energy layer optimization, during which plan quality and delivery efficiency are jointly optimized. In particular, the number of energy jumps (NEJ) is explicitly modelled and minimized during plan optimization for improving delivery efficiency, while target dose conformality and OAR dose objectives are optimized. The plan deliverability is ensured by considering the minimum-monitor-unit (MMU) constraint, and the plan robustness is accounted for using robust optimization. The biological dose is optimized via LET optimization. The optimization solution algorithm utilizes iterative convex relaxation method to handle the dose-volume constraint and the MMU constraint, with spot-weight optimization subproblems solved by proximal descent method.<i>Main results.</i>ARC based proton LATTCE substantially improved plan quality from IMPT based proton LATTICE, such as (1) improved conformity index (CI) from 0.47 to 0.81 for the valley target dose and from 0.62 to 0.97 for the peak target dose, (2) reduced esophagus dose from 0.68 Gy to 0.44 Gy (a 12% reduction with respect to 2 Gy valley prescription dose) and (3) improved PVDR from 4.15 to 4.28 in the lung case. Moreover, energy layer optimization improved plan delivery efficiency for ARC based proton LATTICE, such as (1) reduced NEJ from 71 to 56 and (2) reduction of energy layer switching time by 65% and plan delivery time by 52% in the lung case. The biological target and OAR dose distributions were further enhanced via LET optimization. On the other hand, proton ARC LATTCE also substantially improved plan quality from VMAT LATTICE, such as (1) improved CI from 0.45 to 0.81 for the valley target dose and from 0.63 to 0.97 for the peak target dose, (2) reduced esophagus dose from 0.59 Gy to 0.38 Gy (a 10.5% reduction with respect to 2 Gy valley prescription dose) and (3) improved PVDR from 3.88 to 4.28 in the lung case.<i>Significance.</i>The feasibility of high-plan-qu
目标:这项工作将通过质子 ARC(多射束角)开发新型质子 LATTICE 方法,以克服在靶点覆盖和 OAR 疏导方面的这些挑战,并通过能量层优化和 LET 优化来优化输送效率和生物剂量分布,从而实现质子 LATTICE 的临床应用:基于 ARC 的质子 LATTICE 是通过能量层优化来制定和求解的,在此过程中,计划质量和输送效率得到了共同优化。特别是,在计划优化过程中,对能量跳跃次数(NEJ)进行了明确建模和最小化,以提高投放效率,同时优化目标剂量符合性和 OAR 剂量目标。通过考虑最小监测单元(MMU)约束来确保计划的可投放性,并使用稳健优化来考虑计划的稳健性。生物剂量通过 LET 优化进行优化。优化求解算法采用迭代凸松弛法来处理剂量-体积约束和最小监测单元约束,并通过近似下降法解决定点重量优化子问题:与基于 IMPT 的质子 LATTICE 相比,基于 ARC 的质子 LATTCE 大幅提高了计划质量。能量层优化提高了基于 ARC 的质子 LATTICE 的计划交付效率:与 IMPT 相比,质子 ARC 大幅提高了靶剂量覆盖率和 OAR 损伤清除率,证明了通过质子 ARC 实现高质量质子 LATTICE 计划的可行性,同时可以通过能量层优化来优化基于 ARC 的质子 LATTICE 的计划传输效率。
{"title":"Proton ARC based LATTICE radiation therapy: feasibility study, energy layer optimization and LET optimization.","authors":"Ya-Nan Zhu, Weijie Zhang, Jufri Setianegara, Yuting Lin, Erik Traneus, Yong Long, Xiaoqun Zhang, Rajeev Badkul, David Akhavan, Fen Wang, Ronald C Chen, Hao Gao","doi":"10.1088/1361-6560/ad8855","DOIUrl":"10.1088/1361-6560/ad8855","url":null,"abstract":"&lt;p&gt;&lt;p&gt;&lt;i&gt;Objective.&lt;/i&gt;LATTICE, a spatially fractionated radiation therapy (SFRT) modality, is a 3D generalization of GRID and delivers highly modulated peak-valley spatial dose distribution to tumor targets, characterized by peak-to-valley dose ratio (PVDR). Proton LATTICE is highly desirable, because of the potential synergy of the benefit from protons compared to photons, and the benefit from LATTICE compared to GRID. Proton LATTICE using standard proton RT via intensity modulated proton therapy (IMPT) (with a few beam angles) can be problematic with poor target dose coverage and high dose spill to organs-at-risk (OAR). This work will develop novel proton LATTICE method via proton ARC (with many beam angles) to overcome these challenges in target coverage and OAR sparing, with optimized delivery efficiency via energy layer optimization and optimized biological dose distribution via linear energy transfer (LET) optimization, to enable the clinical use of proton LATTICE.&lt;i&gt;Approach.&lt;/i&gt;ARC based proton LATTICE is formulated and solved with energy layer optimization, during which plan quality and delivery efficiency are jointly optimized. In particular, the number of energy jumps (NEJ) is explicitly modelled and minimized during plan optimization for improving delivery efficiency, while target dose conformality and OAR dose objectives are optimized. The plan deliverability is ensured by considering the minimum-monitor-unit (MMU) constraint, and the plan robustness is accounted for using robust optimization. The biological dose is optimized via LET optimization. The optimization solution algorithm utilizes iterative convex relaxation method to handle the dose-volume constraint and the MMU constraint, with spot-weight optimization subproblems solved by proximal descent method.&lt;i&gt;Main results.&lt;/i&gt;ARC based proton LATTCE substantially improved plan quality from IMPT based proton LATTICE, such as (1) improved conformity index (CI) from 0.47 to 0.81 for the valley target dose and from 0.62 to 0.97 for the peak target dose, (2) reduced esophagus dose from 0.68 Gy to 0.44 Gy (a 12% reduction with respect to 2 Gy valley prescription dose) and (3) improved PVDR from 4.15 to 4.28 in the lung case. Moreover, energy layer optimization improved plan delivery efficiency for ARC based proton LATTICE, such as (1) reduced NEJ from 71 to 56 and (2) reduction of energy layer switching time by 65% and plan delivery time by 52% in the lung case. The biological target and OAR dose distributions were further enhanced via LET optimization. On the other hand, proton ARC LATTCE also substantially improved plan quality from VMAT LATTICE, such as (1) improved CI from 0.45 to 0.81 for the valley target dose and from 0.63 to 0.97 for the peak target dose, (2) reduced esophagus dose from 0.59 Gy to 0.38 Gy (a 10.5% reduction with respect to 2 Gy valley prescription dose) and (3) improved PVDR from 3.88 to 4.28 in the lung case.&lt;i&gt;Significance.&lt;/i&gt;The feasibility of high-plan-qu","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142472543","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
Modeling the oxygen effect in DNA strand break induced by gamma-rays with TOPAS-nBio. 利用 TOPAS-nBio 对伽马射线诱导的 DNA 链断裂中的氧效应进行建模。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-10-25 DOI: 10.1088/1361-6560/ad87a7
Naoki D-Kondo, Thongchai A M Masilela, Wook-Geun Shin, Bruce Faddegon, Jay LaVerne, Jan Schuemann, Jose Ramos-Mendez

Objective.To present and validate a method to simulate from first principles the effect of oxygen on radiation-induced double-strand breaks (DSBs) using the Monte Carlo Track-structure code TOPAS-nBio.Approach.Two chemical models based on the oxygen fixation hypothesis (OFH) were developed in TOPAS-nBio by considering an oxygen adduct state of DNA and creating a competition kinetic mechanism between oxygen and the radioprotective molecule WR-1065. We named these models 'simple' and 'detailed' due to the way they handle the hydrogen abstraction pathways. We used the simple model to obtain additional information for the •OH-DNA hydrogen abstraction pathway probability for the detailed model. These models were calibrated and compared with published experimental data of linear and supercoiling fractions obtained with R6K plasmids, suspended in dioxane as a hydroxyl scavenger, and irradiated with137Cs gamma-rays. The reaction rates for WR-1065 and O2with DNA were taken from experimental works. Single-Strand Breaks (SSBs) and DSBs as a function of the dose for a range of oxygen concentrations [O2] (0.021%-21%) were obtained. Finally, the hypoxia reduction factor (HRF) was obtained from DSBs.Main Results.Validation results followed the trend of the experimental within 12% for the supercoiled and linear plasmid fractions for both models. The HRF agreed with measurements obtained with137Cs and 200-280 kVp x-ray within experimental uncertainties. However, the HRF at an oxygen concentration of 2.1% overestimated experimental results by a factor of 1.7 ± 0.1. Increasing the concentration of WR-1065 from 1 mM to 10-100 mM resulted in a HRF difference of 0.01, within the 8% statistical uncertainty between TOPAS-nBio and experimental data. This highlights the possibility of using these chemical models to recreate experimental HRF results.Significance.Results support the OFH as a leading cause of oxygen radio-sensitization effects given a competition between oxygen and chemical DNA repair molecules like WR-1065.

提出并验证一种方法,利用蒙特卡洛轨道结构代码 TOPAS-nBio 从第一原理上模拟氧对辐射诱导的双链断裂(DSB)的影响。 在 TOPAS-nBio 中,通过考虑 DNA 的氧加成态和创建氧与辐射防护分子 WR-1065 之间的竞争动力学机制,建立了两个基于氧固定假说的化学模型。我们将这些模型命名为 "简单 "和 "详细",因为它们处理氢抽取途径的方式不同。我们使用简单模型为详细模型获取-OH-DNA 取氢途径概率的额外信息。我们对这些模型进行了校准,并与已发表的实验数据进行了比较,这些数据是用 R6K 质粒悬浮在作为羟基清除剂的二氧六环中,并用 137Cs 伽马射线照射后得到的线性和超卷曲部分的数据。WR-1065 和 O2 与 DNA 的反应速率取自实验结果。在不同的氧气浓度[O2](0.021%-21%)下,得到了单链断裂(SSB)和DSB与剂量的函数关系。 两种模型的超卷曲质粒和线性质粒部分的验证结果与实验趋势一致,误差在 12% 以内。HRF 与 137Cs 和 200-280 kVp x 射线的测量结果一致,误差在实验不确定范围内。然而,氧浓度为 2.1% 时的 HRF 高估了实验结果 1.7  0.1 倍。将 WR-1065 的浓度从 1 毫摩尔提高到 10-100 毫摩尔后,HRF 相差 0.01,在 TOPAS-nBio 和实验数据之间 0.08 的统计不确定性范围内。这凸显了使用这些化学模型重现实验 HRF 结果的可能性。 结果支持氧固定假说,认为氧和化学 DNA 修复分子(如 WR-1065)之间的竞争是氧放射增敏效应的主要原因。
{"title":"Modeling the oxygen effect in DNA strand break induced by gamma-rays with TOPAS-nBio.","authors":"Naoki D-Kondo, Thongchai A M Masilela, Wook-Geun Shin, Bruce Faddegon, Jay LaVerne, Jan Schuemann, Jose Ramos-Mendez","doi":"10.1088/1361-6560/ad87a7","DOIUrl":"10.1088/1361-6560/ad87a7","url":null,"abstract":"<p><p><i>Objective.</i>To present and validate a method to simulate from first principles the effect of oxygen on radiation-induced double-strand breaks (DSBs) using the Monte Carlo Track-structure code TOPAS-nBio.<i>Approach.</i>Two chemical models based on the oxygen fixation hypothesis (OFH) were developed in TOPAS-nBio by considering an oxygen adduct state of DNA and creating a competition kinetic mechanism between oxygen and the radioprotective molecule WR-1065. We named these models 'simple' and 'detailed' due to the way they handle the hydrogen abstraction pathways. We used the simple model to obtain additional information for the •OH-DNA hydrogen abstraction pathway probability for the detailed model. These models were calibrated and compared with published experimental data of linear and supercoiling fractions obtained with R6K plasmids, suspended in dioxane as a hydroxyl scavenger, and irradiated with<sup>137</sup>Cs gamma-rays. The reaction rates for WR-1065 and O<sub>2</sub>with DNA were taken from experimental works. Single-Strand Breaks (SSBs) and DSBs as a function of the dose for a range of oxygen concentrations [O<sub>2</sub>] (0.021%-21%) were obtained. Finally, the hypoxia reduction factor (HRF) was obtained from DSBs.<i>Main Results.</i>Validation results followed the trend of the experimental within 12% for the supercoiled and linear plasmid fractions for both models. The HRF agreed with measurements obtained with<sup>137</sup>Cs and 200-280 kVp x-ray within experimental uncertainties. However, the HRF at an oxygen concentration of 2.1% overestimated experimental results by a factor of 1.7 ± 0.1. Increasing the concentration of WR-1065 from 1 mM to 10-100 mM resulted in a HRF difference of 0.01, within the 8% statistical uncertainty between TOPAS-nBio and experimental data. This highlights the possibility of using these chemical models to recreate experimental HRF results.<i>Significance.</i>Results support the OFH as a leading cause of oxygen radio-sensitization effects given a competition between oxygen and chemical DNA repair molecules like WR-1065.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142472540","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
Automated planning of curved needle channels in 3D printed patient-tailored applicators for cervical cancer brachytherapy. 自动规划用于宫颈癌近距离治疗的 3D 打印患者定制涂抹器中的弯曲针道。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-10-24 DOI: 10.1088/1361-6560/ad8b08
Robin Straathof, Sharline M van Vliet-Pérez, Inger-Karine K Kolkman-Deurloo, Linda S G L Wauben, Remi A Nout, Ben J M Heijmen, Linda Rossi, Jenny Dankelman, Nick J van de Berg

Purpose Patient-tailored intracavitary/interstitial (IC/IS) brachytherapy (BT) applicators may increase dose conformity in cervical cancer patients. Current configuration planning methods in these custom applicators rely on manual specification or a small set of (straight) needles. This work introduces and validates a two-stage approach for establishing channel configurations in the 3D printed patient-tailored ARCHITECT applicator. Methods For each patient, the patient-tailored applicator shape was based on the first BT application with a commercial applicator and integrated connectors to a commercial (Geneva) intrauterine tube and two lunar ring channels. First, a large candidate set was generated of channels that steer the needle to desired poses in the target region and are contained in the applicator. The channels' centrelines were represented by Bézier curves. Channels running between straight target segments and entry points were optimised and refined to ensure (dynamic) feasibility. Second, channel configurations were selected using geometric coverage optimisation. This workflow was applied to establish patient-tailored geometries for twenty-two patients previously treated using the Venezia applicator. Treatment plans were automatically generated using the in-house developed algorithm BiCycle. Plans for the clinically used configuration, TPclin, and patient-tailored configuration, TParch, were compared. Results Channel configurations could be generated in clinically feasible time (median: 2651s, range 1826-3812s). All TParchand TPclinplans were acceptable, but planning aims were more frequently attained with patient-tailored configurations (115/132 versus 100/132 instances). Median CTVIRD98and bladderD2cm3doses significantly improved (p< 0.001 andp< 0.01 respectively) in TParchplans in comparison with TPclinplans, and in approximately half of the patients dosimetric indices improved. Conclusion Automated patient-tailored BT channel configuration planning for 3D printed applicators is clinically feasible. A treatment planning study showed that all plans met planning limits for the patient-tailored configurations, and in selected cases improved the plan quality in comparison with commercial applicator configurations. .

目的 为患者量身定制的腔内/间质(IC/IS)近距离放射治疗(BT)应用器可提高宫颈癌患者的剂量一致性。目前这些定制涂抹器的配置规划方法依赖于手动规范或一小套(直)针。这项工作介绍并验证了一种两阶段方法,用于在 3D 打印的患者定制的 ARCHITECT 应用器中建立通道配置。 对于每位患者,患者定制的应用器形状是基于首次使用商用应用器进行的 BT 应用,以及与商用(日内瓦)宫内管和两个月环通道的集成连接器。首先,我们生成了一个庞大的候选通道集,这些通道可将针引导至目标区域的理想位置,并包含在涂抹器中。这些通道的中心线由贝塞尔曲线表示。对直线目标段和入口点之间的通道进行了优化和细化,以确保(动态)可行性。其次,使用几何覆盖优化来选择通道配置。这一工作流程被用于为之前使用 Venezia 治疗仪治疗过的 22 名患者建立适合患者的几何图形。治疗计划通过内部开发的 BiCycle 算法自动生成。对临床常用配置 TPclin 和患者定制配置 TParch 的计划进行了比较。所有 TParch 和 TPclin 计划均可接受,但患者定制的配置更能达到计划目标(115/132 对 100/132)。与 TPclin 计划相比,TParch 计划的中位 CTVIRD98 和膀胱 D2cm3 剂量明显提高(分别为 p< 0.001 和 p< 0.01),约有一半患者的剂量指数得到改善。治疗计划研究表明,所有计划都符合患者定制配置的计划限制,在某些情况下,与商用涂抹器配置相比,计划质量有所提高。
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Physics in medicine and biology
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