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Contrast and quantum noise in single-exposure dual-energy thoracic imaging with photon-counting x-ray detectors. 使用光子计数 X 射线探测器进行单次曝光双能量胸部成像时的对比度和量子噪声。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-09-25 DOI: 10.1088/1361-6560/ad75df
Jeffrey Dhari, Jesse Tanguay

Objective.Photon-counting x-ray detectors (PCDs) can produce dual-energy (DE) x-ray images of lung cancer in a single x-ray exposure. It is important to understand the factors that affect contrast, noise and the contrast-to-noise ratio (CNR). This study quantifies the dependence of CNR on tube voltage, energy threshold and patient thickness in single exposure, DE, bone-suppressed thoracic imaging with PCDs, and elucidates how the fundamental processes inherent in x-ray detection by PCDs contribute to CNR degradation.Approach.We modeled the DE CNR for five theoretical PCDs, ranging from an ideal PCD that detects every primary photon in the correct energy bin while rejecting all scattered radiation to a non-ideal PCD that suffers from charge-sharing and electronic noise, and detects scatter. CNR was computed as a function of tube voltage and high energy threshold for average and larger-than-average patients. Model predictions were compared with experimental data extracted from images acquired using a cadmium telluride (CdTe) PCD with two energy bins and analog charge summing for charge-sharing suppression. The imaging phantom simulated attenuation, scatter and contrast in lung nodule imaging. We quantified CNR improvements achievable with anti-correlated noise reduction (ACNR) and measured the range of exposure rates over which pulse pile-up is negligible.Main Results.The realistic model predicted overall trends observed in the experimental data. CNR improvements with ACNR were approximately five-fold, and modeled CNR-enhancements were on average within 10% of experiment. CNR increased modestly (i.e.<20%) when increasing the tube voltage from 90 kV to 130 kV. Optimal energy thresholds ranged from 50 keV to 70 keV across all tube voltages and patient thicknesses with and without ACNR. Quantum efficiency, electronic noise, charge sharing and scatter degraded CNR by ~50%. Charge sharing and scatter had the largest effect on CNR, degrading it by ~30% and ~15% respectively. Dead-time losses were less than 5% for patient exposure rates within the range of clinical exposure rates.Significance.In this study, we (1) employed analytical and computational models to assess the impact of different factors on CNR in single-exposure DE imaging with PCDs, (2) evaluated the accuracy of these models in predicting experimental trends, (3) quantified improvements in CNR achievable through ACNR and (4) determined the range of patient exposure rates at which pulse pile-up can be considered negligible. To the best of our knowledge, this study represents the first systematic investigation of single-exposure DE imaging of lung nodules with PCDs.

目的:光子计数 X 射线探测器(PCD)可在一次 X 射线曝光中生成肺癌的双能量(DE)X 射线图像。本研究量化了使用 PCD 进行单次曝光、双能量、骨抑制胸部成像时对比度-噪声比(CNR)与管电压、能量阈值和患者厚度的关系,并阐明了 PCD 检测 X 射线的固有过程如何导致 CNR 下降:我们对五种理论 PCD 的 DE CNR 进行了建模,这些 PCD 既有在正确的能量区间检测到每个光子并拒绝散射的理想 PCD,也有受电荷共享和电子噪声影响并检测到散射的非理想 PCD。模型预测结果与使用碲化镉 PCD 采集的图像实验数据进行了比较。成像模型模拟了肺结节成像中的衰减、散射和对比度。我们量化了反相关降噪(AcNR)可实现的 CNR 改进,并测量了脉冲堆积可忽略不计的曝光率范围:在最佳能量阈值下,使用或不使用 ACNR 的模型 CNR 与实验 CNR 的差距在 10%以内。使用 ACNR 时,CNR 提高了约五倍。CNR 增加
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引用次数: 0
Investigating deep learning strategies for fast denoising of 5D cardiac photon-counting micro-CT images. 研究用于 5D 心脏光子计数显微 CT 图像快速去噪的深度学习策略。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-09-25 DOI: 10.1088/1361-6560/ad7fc6
Rohan Nadkarni, Darin P Clark, Alex Jeffrey Allphin, Cristian T Badea

Objective: Photon-counting detectors (PCDs) for CT imaging use energy thresholds to simultaneously acquire projections at multiple energies, making them suitable for spectral imaging and material decomposition. Unfortunately, setting multiple energy thresholds results in noisy analytical reconstructions due to low photon counts in high-energy bins. Iterative reconstruction provides high quality photon-counting CT (PCCT) images but requires enormous computation time for 5D (3D + energy + time) in vivo cardiac imaging. Approach. We recently introduced UnetU, a deep learning (DL) approach that accurately denoises axial slices from 4D (3D + energy) PCCT reconstructions at various acquisition settings. In this study, we explore UnetU configurations for 5D cardiac PCCT denoising, focusing on singular value decomposition (SVD) modifications along the energy and time dimensions and alternate network architectures such as 3D U-net, FastDVDNet, and Swin Transformer UNet. We compare our networks to multi-energy non-local means (ME NLM), an established PCCT denoising algorithm. Main results. Our evaluation, using real mouse data and the digital MOBY phantom, revealed that all DL methods were more than 16 times faster than iterative reconstruction. DL denoising with SVD along the energy dimension was most effective, consistently providing low root mean square error and spatio-temporal reduced reference entropic difference, alongside strong qualitative agreement with iterative reconstruction. This superiority was attributed to lower effective rank along the energy dimension than the time dimension in 5D cardiac PCCT reconstructions. ME NLM sometimes outperformed DL with time SVD or time and energy SVD, but lagged behind iterative reconstruction and DL with energy SVD. Among alternate DL architectures with energy SVD, none consistently outperformed UnetU Energy (2D). Significance. Our study establishes UnetU Energy as an accurate and efficient method for 5D cardiac PCCT denoising, offering a 32-fold speed increase from iterative reconstruction. This advancement sets a new benchmark for DL applications in cardiovascular imaging.

目的: 用于 CT 成像的光子计数探测器(PCD)利用能量阈值同时获取多个能量的投影,使其适用于光谱成像和材料分解。遗憾的是,设置多个能量阈值会导致分析重建时出现噪声,原因是高能量区的光子计数较低。迭代重建可提供高质量的光子计数 CT(PCCT)图像,但对于 5D(3D + 能量 + 时间)活体心脏成像来说,需要耗费大量的计算时间。 方法。 我们最近推出了一种深度学习(DL)方法 UnetU,它能在各种采集设置下对 4D(3D + 能量)PCCT 重建的轴切片进行精确去噪。在本研究中,我们探索了用于 5D 心脏 PCCT 去噪的 UnetU 配置,重点是沿能量和时间维度的奇异值分解 (SVD) 修正,以及 3D U-net、FastDVDNet 和 Swin Transformer UNet 等替代网络架构。 主要结果。 我们使用真实小鼠数据和数字 MOBY 幻影进行评估,结果显示所有 DL 方法都比迭代重建快 16 倍以上。使用 SVD 对能量维度进行去噪的 DL 方法最为有效,其均方根误差和参考熵差的时空缩小率都很低,而且与迭代重建的定性一致。在 5D 心脏 PCCT 重构中,能量维度的有效秩比时间维度的有效秩低,因此具有这种优势。ME NLM 的表现有时优于采用时间 SVD 或时间和能量 SVD 的 DL,但落后于采用能量 SVD 的迭代重建和 DL。 Significance. Our study establishes UnetU Energy as an accurate and efficient method for 5D cardiac PCCT denoication, providing a 32-fold speed increase from iterative reconstruction.这一进步为心血管成像中的 DL 应用树立了新的标杆。
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引用次数: 0
Performance evaluation of image co-registration methods in photoacoustic mesoscopy of the vasculature. 血管光声中视镜图像共聚方法的性能评估。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-09-25 DOI: 10.1088/1361-6560/ad7fc7
Thierry L Lefebvre, Paul W Sweeney, Janek Grohl, Lina Hacker, Emma L Brown, Thomas R Else, Mariam-Eleni Oraiopoulou, Algernon Bloom, David Y Lewis, Sarah E Bohndiek

Objective:The formation of functional vasculature in solid tumours enables delivery of oxygen and nutrients, and is vital for effective treatment with chemotherapeutic agents. Longitudinal characterisation of vascular networks can be enabled using mesoscopic photoacoustic imaging, but requires accurate image co-registration to precisely assess local changes across disease development or in response to therapy. Co-registration in photoacoustic imaging is challenging due to the complex nature of the generated signal, including the sparsity of data, artefacts related to the illumination/detection geometry, scan-to-scan technical variability, and biological variability, such as transient changes in perfusion. To better inform the choice of co-registration algorithms, we compared five open-source methods, in physiological and pathological tissues, with the aim of aligning evolving vascular networks in tumours imaged over growth at different time-points.Approach:Co-registration techniques were applied to 3D vascular images acquired with photoacoustic mesoscopy from murine ears and breast cancer patient-derived xenografts, at a fixed time-point and longitudinally. Images were pre-processed and segmented using an unsupervised generative adversarial network. To compare co-registration quality in different settings, pairs of fixed and moving intensity images and/or segmentations were fed into five methods split into the following categories: affine intensity-based using 1)mutual information (MI) or 2)normalised cross-correlation (NCC) as optimisation metrics, affine shape-based using 3)NCC applied to distance-transformed segmentations or 4)iterative closest point algorithm, and deformable weakly supervised deep learning-based using 5)LocalNet co-registration. Percent-changes in Dice coefficients, surface distances, MI, structural similarity index measure and target registration errors were evaluated.Main results:Co-registration using MI or NCC provided similar alignment performance, better than shape-based methods. LocalNet provided accurate co-registration of substructures by optimising subfield deformation throughout the volumes, outperforming other methods, especially in the longitudinal breast cancer xenograft dataset by minimising target registration errors.Significance:We showed the feasibility of co-registering repeatedly or longitudinally imaged vascular networks in photoacoustic mesoscopy, taking a step towards longitudinal quantitative characterisation of these complex structures. These tools open new outlooks for monitoring tumour angiogenesis at the meso-scale and for quantifying treatment-induced co-localised alterations in the vasculature.

目的:实体瘤中功能性血管的形成有助于氧气和营养物质的输送,对化疗药物的有效治疗至关重要。血管网络的纵向特征可通过介观光声成像来实现,但需要精确的图像配准,才能准确评估疾病发展过程中或治疗反应中的局部变化。由于生成信号的复杂性,包括数据的稀疏性、与照明/检测几何形状有关的伪影、扫描与扫描之间的技术变异性以及生物变异性(如灌注的瞬时变化),光声成像中的共配准具有挑战性。为了更好地选择联合注册算法,我们在生理和病理组织中比较了五种开源方法,目的是在不同的时间点对肿瘤生长过程中成像的不断变化的血管网络进行对齐。方法:联合注册技术应用于鼠耳和乳腺癌患者异种移植物的光声介孔镜获取的三维血管图像,在固定时间点纵向进行。使用无监督生成对抗网络对图像进行预处理和分割。为了比较不同设置下的协同注册质量,固定和移动强度图像和/或分割对被输入到五种方法中,这些方法分为以下几类:基于仿射强度的方法,使用 1)互信息(MI)或 2)归一化交叉相关(NCC)作为优化指标;基于仿射形状的方法,使用 3)应用于距离变换分割的 NCC 或 4)迭代最近点算法;以及基于可变形弱监督深度学习的方法,使用 5)LocalNet 协同注册。主要结果:使用 MI 或 NCC 的协同注册提供了相似的配准性能,优于基于形状的方法。重要意义:我们展示了在光声介孔镜中对重复或纵向成像的血管网络进行共配准的可行性,为这些复杂结构的纵向定量特征描述迈出了一步。这些工具为在中尺度上监测肿瘤血管生成和量化治疗引起的血管共定位改变开辟了新的前景。
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引用次数: 0
Linear energy transfer dependent variation in viability and proliferation along the Bragg peak curve in sarcoma and normal tissue cells. 肉瘤和正常组织细胞的活力和增殖沿布拉格峰曲线的线性能量转移变化。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-09-25 DOI: 10.1088/1361-6560/ad6edc
Teresa Bernardo, Lena Heuchel, Feline Heinzelmann, Johannes Esser, Lutz Lüdemann, Beate Timmermann, Armin Lühr, Cläre von Neubeck

Objective.The energy deposition of photons and protons differs. It depends on the position in the proton Bragg peak (BP) and the linear energy transfer (LET) leading to a variable relative biological effectiveness (RBE). Here, we investigate LET dependent alterations on metabolic viability and proliferation of sarcoma and endothelium cell lines following proton irradiation in comparison to photon exposure.Approach.Using a multi-step range shifter, each column of a 96-well plate was positioned in a different depth along four BP curves with increasing intensities. The high-throughput experimental setup covers dose, LET, and RBE changes seen in a treatment field. Photon irradiation was performed to calculate the RBE along the BP curve. Two biological information out of one experiment were extracted allowing a correlation between metabolic viability and proliferation of the cells.Main results.The metabolic viability and cellular proliferation were column-wise altered showing a depth-dose profile. Endothelium cell viability recovers within 96 h post BP irradiation while sarcoma cell viability remains reduced. Highest RBE values were observed at the BP distal fall-off regarding proliferation of the sarcoma and endothelial cells.Significance.The high-throughput experimental setup introduced here (I) covers dose, LET, and RBE changes seen in a treatment field, (II) measures short-term effects within 48 h to 96 h post irradiation, and (III) can additionally be transferred to various cell types without time consuming experimental adaptations. Traditionally, RBE values are calculated from clonogenic cell survival. Measured RBE profiles strongly depend on physical characteristics such as dose and LET and biological characteristics for example cell type and time point. Metabolic viability and proliferation proofed to be in a similar effect range compared to clonogenic survival results. Based on limited data of combined irradiation with doxorubicin, future experiments will test combined treatment with systemic therapies applied in clinics e.g. cyclin-dependent inhibitors.

目的:光子和质子的能量沉积各不相同。它取决于质子布拉格峰(BP)的位置和线性能量传递(LET),从而导致不同的相对生物效应(RBE)。在此,我们研究了质子辐照与光子辐照相比,对肉瘤和内皮细胞系的代谢活力和增殖所产生的 LET 依赖性变化:使用多级范围转换器(MSRS),将 96 孔板中的每一列沿强度递增的四条 BP 曲线放置在不同深度。高通量实验装置涵盖了治疗场中的剂量、LET 和 RBE 变化。通过光子辐照计算 BP 曲线上的 RBE。从一次实验中提取了两个生物信息,从而将细胞的代谢活力和增殖联系起来:代谢活力和细胞增殖呈柱状变化,显示出深度-剂量曲线。内皮细胞的活力在 BP 照射后 96 小时内恢复,而肉瘤细胞的活力仍然下降。在肉瘤和内皮细胞增殖的 BP 远端落差处观察到了最高的 RBE 值:这里介绍的高通量实验装置 I) 涵盖了治疗场中的剂量、LET 和 RBE 变化;II) 可测量辐照后 48 至 96 小时内的短期效应;III) 还可用于各种细胞类型,而无需耗时的实验调整。传统上,RBE 值是通过克隆细胞存活率计算得出的。测得的 RBE 曲线在很大程度上取决于物理特性(如剂量和 LET)和生物特性(如细胞类型和时间点)。事实证明,代谢活力和增殖与克隆存活结果的影响范围相似。基于联合辐照与多柔比星的有限数据,未来的实验将测试与临床应用的系统疗法(如细胞周期蛋白依赖性抑制剂)联合治疗的效果。
{"title":"Linear energy transfer dependent variation in viability and proliferation along the Bragg peak curve in sarcoma and normal tissue cells.","authors":"Teresa Bernardo, Lena Heuchel, Feline Heinzelmann, Johannes Esser, Lutz Lüdemann, Beate Timmermann, Armin Lühr, Cläre von Neubeck","doi":"10.1088/1361-6560/ad6edc","DOIUrl":"10.1088/1361-6560/ad6edc","url":null,"abstract":"<p><p><i>Objective.</i>The energy deposition of photons and protons differs. It depends on the position in the proton Bragg peak (BP) and the linear energy transfer (LET) leading to a variable relative biological effectiveness (RBE). Here, we investigate LET dependent alterations on metabolic viability and proliferation of sarcoma and endothelium cell lines following proton irradiation in comparison to photon exposure.<i>Approach.</i>Using a multi-step range shifter, each column of a 96-well plate was positioned in a different depth along four BP curves with increasing intensities. The high-throughput experimental setup covers dose, LET, and RBE changes seen in a treatment field. Photon irradiation was performed to calculate the RBE along the BP curve. Two biological information out of one experiment were extracted allowing a correlation between metabolic viability and proliferation of the cells.<i>Main results.</i>The metabolic viability and cellular proliferation were column-wise altered showing a depth-dose profile. Endothelium cell viability recovers within 96 h post BP irradiation while sarcoma cell viability remains reduced. Highest RBE values were observed at the BP distal fall-off regarding proliferation of the sarcoma and endothelial cells.<i>Significance.</i>The high-throughput experimental setup introduced here (I) covers dose, LET, and RBE changes seen in a treatment field, (II) measures short-term effects within 48 h to 96 h post irradiation, and (III) can additionally be transferred to various cell types without time consuming experimental adaptations. Traditionally, RBE values are calculated from clonogenic cell survival. Measured RBE profiles strongly depend on physical characteristics such as dose and LET and biological characteristics for example cell type and time point. Metabolic viability and proliferation proofed to be in a similar effect range compared to clonogenic survival results. Based on limited data of combined irradiation with doxorubicin, future experiments will test combined treatment with systemic therapies applied in clinics e.g. cyclin-dependent inhibitors.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141976366","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
Quantitative evaluation of anti-biofilm cavitation activity seeded from microbubbles or protein cavitation nuclei by passive acoustic mapping. 通过被动声学图谱定量评估由微气泡或蛋白质空化核产生的抗生物膜空化活性。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-09-24 DOI: 10.1088/1361-6560/ad7f1a
Sara Keller, Gareth LuTheryn, Michael Gray, Brian Lyons, Robin O Cleveland, Eleanor Stride, Constantin C Coussios

Objective: Bacterial biofilms represent a major challenge for effective antibiotic therapy as they confer physical and functional changes that protect bacteria from their surrounding environment. In this work, focused ultrasound in combination with cavitation nuclei was used to disrupt biofilms of Staphylococcus aureus and Pseudomonas aeruginosa, both of which are on the World Health Organization's priority list for new antimicrobial research. Approach: Single species biofilms were exposed to ultrasound (0.5 MHz centre frequency, 0.5-1.5 MPa peak rarefactional pressure, 200 cycle pulses, 5 Hz repetition frequency, 30 s duration), in the presence of two different types of cavitation nuclei. Quantitative passive acoustic mapping (PAM) was used to monitor cavitation emissions during treatment using a calibrated linear array. Main Results: It was observed that the cumulative energy of acoustic emissions during treatment was positively correlated with biofilm disruption, with differences between bacterial species attributed to differences in biofilm morphology. PCaN provided increased biofilm reduction compared to microbubbles due in large part to their persistence over the duration of ultrasound exposure. There was also good correlation between the spatial distribution of cavitation as characterized by PAM and the extent of biofilm disruption observed with microscopy. Significance: Collectively, the results from this work indicate the potential broad applicability of cavitation for eliminating biofilms of priority pathogens and the opportunity presented by Passive Acoustic Mapping for real-time monitoring of antimicrobial processes.

目的:细菌生物膜是有效抗生素疗法面临的一大挑战,因为生物膜会产生物理和功能变化,保护细菌免受周围环境的侵害。在这项研究中,聚焦超声与空化核相结合,用于破坏金黄色葡萄球菌和铜绿假单胞菌的生物膜:在两种不同类型的空化核存在的情况下,将单种生物膜暴露于超声波(中心频率为 0.5 MHz,峰值稀释压力为 0.5-1.5 MPa,脉冲周期为 200 个,重复频率为 5 Hz,持续时间为 30 秒)中。使用校准线性阵列对治疗过程中的空化发射进行了定量被动声学绘图(PAM)监测:观察发现,治疗期间声发射的累积能量与生物膜破坏呈正相关,细菌种类之间的差异归因于生物膜形态的不同。与微气泡相比,PCaN能更有效地减少生物膜,这在很大程度上是由于PCaN在超声暴露持续时间内具有持久性。用 PAM 表征的空化空间分布与显微镜观察到的生物膜破坏程度之间也有很好的相关性:总之,这项工作的结果表明,空化技术在消除重点病原体的生物膜方面具有潜在的广泛适用性,而被动声学绘图技术则为实时监控抗菌过程提供了机会。
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引用次数: 0
Deep learning-based statistical robustness evaluation of intensity-modulated proton therapy for head and neck cancer. 基于深度学习的头颈癌强度调制质子疗法统计鲁棒性评估
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-09-20 DOI: 10.1088/1361-6560/ad780b
Danfu Liang, Ivan Vazquez, Mary P Gronberg, Xiaodong Zhang, X Ronald Zhu, Steven J Frank, Laurence E Court, Mary K Martel, Ming Yang

Objective. Previous methods for robustness evaluation rely on dose calculation for a number of uncertainty scenarios, which either fails to provide statistical meaning when the number is too small (e.g., ∼8) or becomes unfeasible in daily clinical practice when the number is sufficiently large (e.g., >100). Our proposed deep learning (DL)-based method addressed this issue by avoiding the intermediate dose calculation step and instead directly predicting the percentile dose distribution from the nominal dose distribution using a DL model. In this study, we sought to validate this DL-based statistical robustness evaluation method for efficient and accurate robustness quantification in head and neck (H&N) intensity-modulated proton therapy with diverse beam configurations and multifield optimization.Approach. A dense, dilated 3D U-net was trained to predict the 5th and 95th percentile dose distributions of uncertainty scenarios using the nominal dose and planning CT images. The data set comprised proton therapy plans for 582 H&N cancer patients. Ground truth percentile values were estimated for each patient through 600 dose recalculations, representing randomly sampled uncertainty scenarios. The comprehensive comparisons of different models were conducted for H&N cancer patients, considering those with and without a beam mask and diverse beam configurations, including varying beam angles, couch angles, and beam numbers. The performance of our model trained based on a mixture of patients with H&N and prostate cancer was also assessed in contrast with models trained based on data specific for patients with cancer at either site.Results. The DL-based model's predictions of percentile dose distributions exhibited excellent agreement with the ground truth dose distributions. The average gamma index with 2 mm/2%, consistently exceeded 97% for both 5th and 95th percentile dose volumes. Mean dose-volume histogram error analysis revealed that predictions from the combined training set yielded mean errors and standard deviations that were generally similar to those in the specific patient training data sets.Significance. Our proposed DL-based method for evaluation of the robustness of proton therapy plans provides precise, rapid predictions of percentile dose for a given confidence level regardless of the beam arrangement and cancer site. This versatility positions our model as a valuable tool for evaluating the robustness of proton therapy across various cancer sites.

以往的稳健性评估方法依赖于对一些不确定情况进行剂量计算,当数量太小时(如~8),这种方法无法提供统计意义;当数量足够大时(如>100),这种方法在日常临床实践中变得不可行。我们提出的基于深度学习的方法避免了中间剂量计算步骤,而是使用深度学习(DL)模型直接从名义剂量分布预测百分位数剂量分布,从而解决了这一问题。在本研究中,我们试图验证这种基于深度学习(DL)的统计鲁棒性评估(SRE)方法,以在头颈部(H&N)强度调制质子治疗中使用不同的射束配置和多场优化进行高效、准确的鲁棒性量化:方法:使用标称剂量和计划 CT 图像训练密集、扩张的三维 U 网,以预测计划剂量计划的第 5 百分位数和第 95 百分位数分布。数据集包括 582 名 H&N 癌症患者的质子治疗计划。每个患者的地面真实百分位值是通过 600 次剂量重新计算估算得出的,代表随机抽样的不确定情况。针对 H&N 癌症患者对不同模型进行了综合比较,考虑到了有无光束掩膜 (BM) 的患者以及不同的光束配置,包括不同的光束角、坐榻角和光束数。我们还评估了根据 H&N 和前列腺癌患者混合数据训练的模型的性能,并与根据任一部位癌症患者的特定数据训练的模型进行了对比:结果:基于 DL 的模型对百分位数剂量分布的预测与地面实况剂量分布非常吻合。第 5 和第 95 百分位数剂量体积的平均伽马指数(2 毫米/2%)始终超过 97%。平均剂量-体积直方图误差分析表明,综合训练集预测的平均误差和标准偏差与特定患者训练数据集的误差和标准偏差基本相似:我们提出的基于 DL 的质子治疗计划稳健性评估方法,可以在给定置信度下精确、快速地预测百分位数剂量,而不受射束排列和癌症部位的影响。这种多功能性使我们的模型成为评估不同癌症部位质子治疗稳健性的重要工具。
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引用次数: 0
Simultaneous iodine and barium imaging with photon-counting CT. 利用光子计数 CT 同时进行碘和钡成像。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-09-20 DOI: 10.1088/1361-6560/ad7775
Xinchen Deng, Devon Richtsmeier, Pierre-Antoine Rodesch, Kris Iniewski, Magdalena Bazalova-Carter

Objective.The objective of this study is to explore the capabilities of photon-counting computed tomography (PCCT) in simultaneously imaging and differentiating materials with close atomic numbers, specifically barium (Z= 56) and iodine (Z= 53), which is challenging for conventional computed tomography (CT).Approach.Experiments were conducted using a bench-top PCCT system equipped with a cadmium zinc telluride detector. Various phantom setups and contrast agent concentrations (1%-5%) were employed, along with a biological sample. Energy thresholds were tuned to the K-edge absorption energies of barium (37.4 keV) and iodine (33.2 keV) to capture multi-energy CT images. K-edge decomposition was performed using K-edge subtraction and principal component analysis (PCA) techniques to differentiate and quantify the contrast agents.Main results.The PCCT system successfully differentiated and accurately quantified barium and iodine in both phantom combinations and a biological sample, achieving high correlations (R2≈1) between true and reconstructed concentrations. PCA outperformed K-edge subtraction, particularly in the presence of calcium, by providing superior differentiation between barium and iodine.Significance.This study demonstrates the potential of PCCT for reliable, detailed imaging in both clinical and research settings, particularly for contrast agents with similar atomic numbers. The results suggest that PCCT could offer significant improvements in imaging quality over conventional CT, especially in applications requiring precise material differentiation.

与传统 CT 相比,光子计数计算机断层扫描 (PCCT) 有可能显著提高图像质量。本研究利用光子计数计算机断层扫描技术实现了钡(Z=56)和碘(Z=53)的同步多对比成像,解决了传统 CT 在区分原子序数相似的材料方面的局限性。利用带有碲化镉锌(CZT)探测器的台式 PCCT 系统,使用各种模型设置和 1-5% 的对比剂浓度,并在生物样本中进行了实验。能量阈值根据钡(37.4 keV)和碘(33.2 keV)的 K 边吸收能量进行了调整,以捕捉多能量 CT 图像。利用 K 边减法和主成分分析 (PCA) 技术对 K 边进行分解,结果表明,模型组合和生物样本中的造影剂均能得到清晰的区分和准确的量化。PCCT 系统成功地区分并量化了钡和碘,真实浓度和重建浓度之间具有很高的相关性(R^2 约为 1)。PCA 在区分钡和碘方面的能力优于 K 边减法,尤其是在扫描对象中存在钙的情况下。这些发现凸显了 PCCT 在临床和研究应用中进行可靠、详细成像的潜力,特别是对于原子序数接近的造影剂。
{"title":"Simultaneous iodine and barium imaging with photon-counting CT.","authors":"Xinchen Deng, Devon Richtsmeier, Pierre-Antoine Rodesch, Kris Iniewski, Magdalena Bazalova-Carter","doi":"10.1088/1361-6560/ad7775","DOIUrl":"10.1088/1361-6560/ad7775","url":null,"abstract":"<p><p><i>Objective.</i>The objective of this study is to explore the capabilities of photon-counting computed tomography (PCCT) in simultaneously imaging and differentiating materials with close atomic numbers, specifically barium (<i>Z</i>= 56) and iodine (<i>Z</i>= 53), which is challenging for conventional computed tomography (CT).<i>Approach.</i>Experiments were conducted using a bench-top PCCT system equipped with a cadmium zinc telluride detector. Various phantom setups and contrast agent concentrations (1%-5%) were employed, along with a biological sample. Energy thresholds were tuned to the K-edge absorption energies of barium (37.4 keV) and iodine (33.2 keV) to capture multi-energy CT images. K-edge decomposition was performed using K-edge subtraction and principal component analysis (PCA) techniques to differentiate and quantify the contrast agents.<i>Main results.</i>The PCCT system successfully differentiated and accurately quantified barium and iodine in both phantom combinations and a biological sample, achieving high correlations (R2≈1) between true and reconstructed concentrations. PCA outperformed K-edge subtraction, particularly in the presence of calcium, by providing superior differentiation between barium and iodine.<i>Significance.</i>This study demonstrates the potential of PCCT for reliable, detailed imaging in both clinical and research settings, particularly for contrast agents with similar atomic numbers. The results suggest that PCCT could offer significant improvements in imaging quality over conventional CT, especially in applications requiring precise material differentiation.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142133467","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
Fractionation dose optimization facilities the implementation of transmission proton FLASH-RT. 实施透射质子 FLASH-RT 的分馏剂量优化设施。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-09-19 DOI: 10.1088/1361-6560/ad75e3
Yiling Zeng, Qi Zhang, Bo Pang, Muyu Liu, Yu Chang, Ye Wang, Hong Quan, Zhiyong Yang

Objective.The beam switching time and fractional dose influence the FLASH effect. A single-beam-per-fraction (SBPF) scheme using uniform fractional dose (UFD) has been proposed for FLASH- radiotherapy (FLASH-RT) to eliminate the beam switching time. Based on SBPF schemes, a fractionation dose optimization algorithm is proposed to optimize non-UFD plans to maximize the fractionation effect and dose-dependent FLASH effect.Approach.The UFD plan, containing five 236 MeV transmission proton beams, was optimized for 11 patients with peripheral lung cancer, with each beam delivering a uniform dose of 11 Gy to the target. Meanwhile, the non-UFD plan was optimized using fractionation dose optimization. To compare the two plans, the equivalent dose to 2 Gy (EQD2) for the target and normal tissues was calculated with anα/βratio of 10 and 3, respectively. Both UFD and non-UFD plans ensured that the target received an EQD2 of 96.3 Gy. To investigate the overall improvement in normal tissue sparing with the non-UFD plan, the FLASH-enhanced EQD2 was calculated.Main results.The fractional doses in non-UFD plans ranged between 5.0 Gy and 24.2 Gy. No significant differences were found in EQD22%and EQD298%of targets between UFD and non-UFD plans. However, theD95%of the target in non-UFD plans was significantly reduced by 15.1%. The sparing effect in non-UFD plans was significantly improved. The FLASH-enhanced EQD2meanin normal tissue and ipsilateral lung was significantly reduced by 3.5% and 10.4%, respectively, in non-UFD plans. The overall improvement is attributed to both the FLASH and fractionation effects.Significance.The fractionation dose optimization can address the limitation of multiple-beam FLASH-RT and utilize the relationship between fractional dose and FLASH effect. Consequently, the non-UFD scheme results in further improvements in normal tissue sparing compared to the UFD scheme, attributed to enhanced fractionation and FLASH effects.

目的:光束切换时间和分数剂量会影响 FLASH 效果。针对 FLASH-RT 提出了一种使用均匀分数剂量(UFD)的单束每分数(SBPF)方案,以消除束切换时间。在 SBPF 方案的基础上,提出了一种分馏剂量优化算法,用于优化非均匀分馏剂量(non-UFD)计划,以最大限度地提高分馏效果和剂量相关的 FLASH 效果:为11名周围型肺癌患者优化了包含5束236MeV透射质子束的UFD计划,每束质子束向靶点提供11Gy的均匀剂量。与此同时,还采用了分次剂量优化法对非 UFD 方案进行了优化。为了比较这两种方案,计算了靶组织和正常组织的2 Gy当量剂量(EQD2),α/β比值分别为10和3。UFD 和非 UFD 计划都确保了靶组织获得 96.3 Gy 的 EQD2。为了研究非 UFD 方案在疏通正常组织方面的整体改善情况,计算了 FLASH 增强 EQD2:非 UFD 计划的部分剂量介于 5.0 Gy 和 24.2 Gy 之间。在 UFD 和非 UFD 计划中,目标的 EQD22% 和 EQD298% 没有发现明显差异。但是,非超常脱发计划的目标 D95% 显著降低了 15.1%。非 UFD 计划的疏导效果明显改善。在非 UFD 计划中,正常组织和同侧肺的 FLASH 增强 EQD2 平均值分别显著降低了 3.5% 和 10.4%。总体改善归因于 FLASH 和分馏效应:分馏剂量优化可以解决多束 FLASH-RT 的局限性,并利用分馏剂量与 FLASH 效应之间的关系。因此,与 UFD 方案相比,非 UFD 方案由于增强了分馏和 FLASH 效应,进一步改善了对正常组织的保护。
{"title":"Fractionation dose optimization facilities the implementation of transmission proton FLASH-RT.","authors":"Yiling Zeng, Qi Zhang, Bo Pang, Muyu Liu, Yu Chang, Ye Wang, Hong Quan, Zhiyong Yang","doi":"10.1088/1361-6560/ad75e3","DOIUrl":"10.1088/1361-6560/ad75e3","url":null,"abstract":"<p><p><i>Objective.</i>The beam switching time and fractional dose influence the FLASH effect. A single-beam-per-fraction (SBPF) scheme using uniform fractional dose (UFD) has been proposed for FLASH- radiotherapy (FLASH-RT) to eliminate the beam switching time. Based on SBPF schemes, a fractionation dose optimization algorithm is proposed to optimize non-UFD plans to maximize the fractionation effect and dose-dependent FLASH effect.<i>Approach.</i>The UFD plan, containing five 236 MeV transmission proton beams, was optimized for 11 patients with peripheral lung cancer, with each beam delivering a uniform dose of 11 Gy to the target. Meanwhile, the non-UFD plan was optimized using fractionation dose optimization. To compare the two plans, the equivalent dose to 2 Gy (EQD2) for the target and normal tissues was calculated with an<i>α</i>/<i>β</i>ratio of 10 and 3, respectively. Both UFD and non-UFD plans ensured that the target received an EQD2 of 96.3 Gy. To investigate the overall improvement in normal tissue sparing with the non-UFD plan, the FLASH-enhanced EQD2 was calculated.<i>Main results.</i>The fractional doses in non-UFD plans ranged between 5.0 Gy and 24.2 Gy. No significant differences were found in EQD2<sub>2%</sub>and EQD2<sub>98%</sub>of targets between UFD and non-UFD plans. However, the<i>D</i><sub>95%</sub>of the target in non-UFD plans was significantly reduced by 15.1%. The sparing effect in non-UFD plans was significantly improved. The FLASH-enhanced EQD2<sub>mean</sub>in normal tissue and ipsilateral lung was significantly reduced by 3.5% and 10.4%, respectively, in non-UFD plans. The overall improvement is attributed to both the FLASH and fractionation effects.<i>Significance.</i>The fractionation dose optimization can address the limitation of multiple-beam FLASH-RT and utilize the relationship between fractional dose and FLASH effect. Consequently, the non-UFD scheme results in further improvements in normal tissue sparing compared to the UFD scheme, attributed to enhanced fractionation and FLASH effects.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142110919","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
A wideband model to evaluate the dielectric properties of biological tissues from magnetic resonance acquisitions. 通过磁共振采集评估生物组织介电特性的宽带模型。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-09-18 DOI: 10.1088/1361-6560/ad708b
Flavia Liporace, Marta Cavagnaro

Objective. Aim of this work is to illustrate and experimentally validate a model to evaluate the dielectric properties of biological tissues on a wide frequency band using the magnetic resonance imaging (MRI) technique.Approach. The dielectric behaviour of biological tissues depends on frequency, according to the so-called relaxation mechanisms. The adopted model derives the dielectric properties of biological tissues in the frequency range 10 MHz-20 GHz considering the presence of two relaxation mechanisms whose parameters are determined from quantities derived from MRI acquisitions. In particular, the MRI derived quantities are the water content and the dielectric properties of the tissue under study at the frequency of the MR scanner.Main results.The model was first theoretically validated on muscle and fat using literature data in the frequency range 10 MHz-20 GHz. Results showed capabilities of reconstructing dielectric properties with errors within 16%. Then the model was applied to ex vivo muscle and liver tissues, comparing the MRI-derived properties with data measured by the open probe technique in the frequency range 10 MHz-3 GHz, showing promising results.Significance. The use of medical techniques based on the application of electromagnetic fields (EMFs) is significantly increasing. To provide safe and effective treatments, it is necessary to know how human tissues react to the applied EMF. Since this information is embedded in the dielectric properties of biological tissues, an accurate and precise dielectric characterization is needed. Biological tissues are heterogenous, and their characteristics depend on several factors. Consequently, it is necessary to characterize dielectric propertiesin vivofor each specific patient. While this aim cannot be reached with traditional measurement techniques, through the adopted model these properties can be reconstructedin vivoon a wide frequency band from non-invasive MRI acquisitions.

目的:这项工作的目的是说明和实验验证一个模型,利用磁共振成像(MRI)技术评估生物组织在宽频带的介电特性:这项工作的目的是利用磁共振成像(MRI)技术,说明并通过实验验证一个用于评估宽频带生物组织介电特性的模型:方法:根据所谓的弛豫机制,生物组织的介电性能取决于频率。所采用的模型考虑到两种弛豫机制的存在,推导出生物组织在 10 MHz - 20 GHz 频率范围内的介电特性。特别是,核磁共振成像的导出量是所研究组织在核磁共振扫描仪频率下的含水量和介电特性:该模型首先利用 10 MHz - 20 GHz 频率范围内的文献数据对肌肉和脂肪进行了理论验证。结果表明,该模型能够重建介电特性,误差在 16% 以内。然后,该模型被应用于体外肌肉和肝脏组织,将核磁共振成像得出的属性与开放探针技术在 10 MHz - 3 GHz 频率范围内测得的数据进行比较,结果显示效果良好:基于电磁场应用的医疗技术的使用正在显著增加。为了提供安全有效的治疗,有必要了解人体组织对应用电磁场的反应。由于这一信息蕴含在生物组织的介电特性中,因此需要准确和精确的介电表征。生物组织是异质的,其特性取决于多种因素。因此,有必要对每个特定患者的体内介电特性进行表征。虽然传统的测量技术无法实现这一目标,但通过所采用的模型,这些特性可以在体内通过无创磁共振成像采集在宽频带上重建。
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引用次数: 0
Radial dependence of ionization clustering around a gold nanoparticle irradiated by X-rays under charged particle equilibrium. 带电粒子平衡状态下 X 射线辐照金纳米粒子周围电离聚类的径向依赖性。
IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL Pub Date : 2024-09-13 DOI: 10.1088/1361-6560/ad6e4f
Leo Thomas, Miriam Schwarze, Hans Rabus

Objective.This work explores the enhancement of ionization clustering and its radial dependence around a gold nanoparticle (NP), indicative of the induction of DNA lesions, a potential trigger for cell-death.Approach.Monte Carlo track structure simulations were performed to determine (a) the spectral fluence of incident photons and electrons in water around a gold NP under charged particle equilibrium conditions and (b) the density of ionization clusters produced on average as well as conditional on the occurrence of at least one interaction in the NP using Associated Volume Clustering. Absorbed dose was determined for comparison with a recent benchmark intercomparison. Reported quantities are normalized to primary fluence, allowing to establish a connection to macroscopic dosimetric quantities.Main results.The modification of the electron spectral fluence by the gold NP is minor and mainly occurs at low energies. The net fluence of electrons emitted from the NP is dominated by electrons resulting from photon interactions. Similar to the known dose enhancement, increased ionization clustering is limited to a distance from the NP surface of up to200nm. The number of clusters per energy imparted is increased at distances of up to150nm, and accordingly the enhancement in clustering notably surpasses that of dose enhancement. Smaller NPs cause noticeable peaks in the conditional frequency of clusters between50nm-100nmfrom the NP surface.Significance.This work shows that low energy electrons emitted by NPs lead to an increase of ionization clustering in their vicinity exceeding that of energy imparted. While the electron component of the radiation field plays an important role in determining the background contribution to ionization clustering and energy imparted, the dosimetric effects of NPs are governed by the interplay of secondary electron production by photon interaction and their ability to leave the NP.

目的:这项研究探索了金纳米粒子(NP)周围电离聚类的增强及其径向依赖性,这表明 DNA 病变的诱导,而 DNA 病变是细胞死亡的潜在诱因:进行蒙特卡罗轨道结构模拟以确定:(a) 在带电粒子平衡条件下,金纳米粒子周围水中入射光子和电子的光谱通量;(b) 平均产生的电离簇密度,以及利用关联体积聚类(Associated Volume Clustering)在纳米粒子中发生至少一次相互作用的条件下产生的电离簇密度。测定吸收剂量是为了与最近的基准相互比较进行比较。报告中的数据均归一化为原始通量,以便与宏观剂量学数据建立联系:金 NP 对电子光谱通量的改变很小,而且主要发生在低能量时。NP 发出的电子净通量主要是光子相互作用产生的电子。与已知的剂量增强类似,电离簇的增加仅限于与 NP 表面的距离不超过 200 纳米的范围。在距离达 150 nm 时,每传导一个能量所产生的电离簇数量会增加,因此电离簇的增强明显超过了剂量的增强。较小的 NP 在距离 NP 表面 50 nm 到 100 nm 的范围内会使集群的条件频率出现明显的峰值:这项工作表明,纳米粒子发射的低能电子导致其附近电离簇的增加超过了能量传递的增加。 虽然辐射场中的电子成分在决定电离簇和能量传递的背景贡献方面起着重要作用,但纳米粒子的剂量学效应受光子相互作用产生的二次电子及其离开纳米粒子的能力的相互作用的支配。
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引用次数: 0
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Physics in medicine and biology
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