Physica Medica-European Journal of Medical Physics最新文献

英文中文

Comparison of two biologically effective dose calculation models applied to single fraction stereotactic radiosurgery 两种生物有效剂量计算模型在单次分次立体定向放射手术中的应用比较

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2024-09-27 DOI: 10.1016/j.ejmp.2024.104820

Background

Recent studies suggest strong correlations between Biologically Effective Doses (BED) and single fraction stereotactic radiosurgery treatment outcomes, as demonstrated for vestibular schwannomas (VS), arterio-venous malformations and pituitary adenomas. The BEDs calculated in these studies consider an uniform dose delivery where the spatio-temporal aspects of dose delivery were neglected.

Purpose

The aim of the study is to quantify the discrepancies between the BED values calculated with a simplified model of uniform dose delivery against the more complex model that incorporates the temporo-spatial incrementation of dose delivery and the bi-exponential effect of the sub-lethal damage repair.

Methods

A software tool that computes the BED distributions based on individual isocenter dose matrices extracted from the GammaPlan (Elekta) treatment planning was developed. Two cohorts 5 VS and 5 jugular foramen schwannoma cases of various tumor volumes and isocenter number were utilized to benchmark the method. Their BEDs covering 98% of tumor volumes were compared against those determined with the uniform delivery model.

Results

The BEDs covering 98% of the tumor volumes as calculated with both models show an approximately linear dependency with the treatment time. For all studied cases, the uniform delivery model overestimates the BEDs calculated with the full spatio-temporal delivery model. This discrepancy seems to accentuate with the tumor volume and treatment complexity.

Conclusions

Despite their resemblance, the BED distributions provide a plethora of BED measures more suitable to characterize clinical outcomes than the unique peripheral BED value calculated with the simplified model of uniform dose delivery.

背景最近的研究表明，生物有效剂量（BED）与单次分量立体定向放射外科治疗效果之间存在密切联系，前庭裂隙瘤（VS）、动静脉畸形和垂体腺瘤的治疗效果就证明了这一点。目的本研究的目的是量化均匀剂量投放简化模型与包含剂量投放的时空递增和亚致死损伤修复的双指数效应的更复杂模型所计算出的 BED 值之间的差异。方法开发了一种软件工具，可根据从 GammaPlan（Elekta）治疗计划中提取的单个等中心剂量矩阵计算 BED 分布。利用两组不同肿瘤体积和等中心数的 5 个 VS 和 5 个颈静脉裂孔型耳鸣瘤病例来对该方法进行基准测试。结果两种模型计算出的覆盖 98% 肿瘤体积的 BED 与治疗时间呈近似线性关系。在所有研究病例中，均匀给药模型都高估了全时空给药模型计算出的 BED。结论尽管 BED 分布与均匀剂量给药简化模型相似，但它们提供的大量 BED 测量值比用均匀剂量给药简化模型计算的唯一外围 BED 值更适合描述临床结果。

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引用次数: 0

LatticeOpt: An automatic tool for planning optimisation of spatially fractionated stereotactic body radiotherapy LatticeOpt：空间分割立体定向体放射治疗规划优化自动工具

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2024-09-26 DOI: 10.1016/j.ejmp.2024.104823

Purpose

Lattice radiotherapy (LRT) is a three dimensional (3D) implementation of spatially fractionated radiation therapy, based on regular spatial distribution of high dose spheres (vertices) inside the target. Due to tumour shape heterogeneity, finding the best lattice arrangement is not trivial.

The aim of this study was to develop the LatticeOpt tool to generate the best lattice structures on clinical cases for treatment planning.

Methods

Developed in MATLAB, LatticeOpt finds the 3D-spatial configurations that maximize the number of vertices within the gross target volume (GTV). If organs at risk (OARs) are considered, it chooses the solution that minimizes the overlapping volume histograms (OVH). Otherwise, the lattice structure with the minimum Hausdorff distance between vertices and GTV boundary is chosen to avoid unpopulated regions.

Different lattice structures were created for 20 patients, with (OVHopt) and without (OVHunopt) OVH minimization. Imported into TPS (Eclipse, Varian), corresponding plans were generated and evaluated in terms of OAR mean and maximum doses, GTV vertex coverage and dose gradients, as well as pre-clinical plan dosimetry.

Results

Plans based on an optimized lattice structure (OVHopt, OVHunopt) had similar dose distributions in terms of vertex coverage and gradient index score. OAR sparing was observed in all patients, with a 4 % and 9 % difference for mean and max dose (both p-values <0.01), respectively. The best vertices dimensions and their relative distances were patient dependent.

Conclusions

LatticeOpt was able to reduce the time-consuming procedures of LRT, as well as to achieve standardized and reproducible results, useful for multicentre studies.

目的网格放射治疗（LRT）是一种三维（3D）空间分割放射治疗方法，基于靶体内高剂量球体（顶点）的规则空间分布。本研究的目的是开发 LatticeOpt 工具，以便在临床病例中生成最佳的格子结构，用于制定治疗计划。方法 LatticeOpt 是在 MATLAB 中开发的，它能找到使总靶体积（GTV）内顶点数量最大化的三维空间配置。如果考虑到危险器官（OAR），则选择重叠体积直方图（OVH）最小的解决方案。否则，将选择顶点与 GTV 边界之间 Hausdorff 距离最小的晶格结构，以避免出现未填充区域。我们为 20 名患者创建了不同的晶格结构，包括（OVHopt）和（OVHunopt）OVH 最小化。结果基于优化晶格结构（OVHopt、OVHunopt）的计划在顶点覆盖和梯度指数评分方面具有相似的剂量分布。所有患者都观察到了OAR疏散，平均剂量和最大剂量分别相差4%和9%（p值均为0.01）。结论LatticeOpt能够减少LRT的耗时过程，并获得标准化和可重复的结果，对多中心研究非常有用。

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引用次数: 0

Advanced mathematical modeling for preciseestimation of CT energy spectrum using a calibration phantom 利用校准模型精确估算 CT 能谱的高级数学模型

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2024-09-26 DOI: 10.1016/j.ejmp.2024.104819

Purpose

This research aims to develop an advanced mathematical model using a CT calibration phantom to accurately estimate the CT energy spectrum in clinical settings, enhancing imaging quality and patient dose management.

Methods

Data were collected from a CT scanner using a CT calibration phantom at various energy levels (80, 100, 120, and 135 kVp). The data was optimized to refine the energy spectrum model, followed by cross-validation with Monte Carlo simulations.

Results

The developed model demonstrated high precision in estimating the CT energy spectrum at all tested energy levels, with R-squared values above 0.9738 and an R-squared value of 0.9829 at 100 kVp. The model also showed low Normalized Root Mean Square Deviation (NRMSD) ranging from 0.6698 % to 1.8745 %. The Mean Energy Difference (ΔE) between the estimated and simulated spectrum consistently remained under 0.01 keV. These results were comparable to recent studies, which reported higher NRMSD and ΔE.

Conclusions

This study presents a significantly improved model for estimating the CT energy spectrum, offering greater accuracy than existing models. Its strengths include high precision and the use of standard equipment and algorithmic values. While the current use of 13 plugs is adequate, incorporating plugs with varied densities could enhance accuracy. This model has potential for improving imaging quality and optimizing patient dosing in clinical applications. Future trends may include extending energy spectrum estimation to megavoltage domains and integrating technologies like EPID and MVCT for better dose distribution prediction in high-energy photon beam therapy.

目的本研究旨在利用 CT 校准模型开发一种先进的数学模型，以准确估计临床环境中的 CT 能量谱，从而提高成像质量和患者剂量管理水平。结果所开发的模型在所有测试能级下都能高精度地估计 CT 能谱，R 方值超过 0.9738，在 100 kVp 时 R 方值为 0.9829。该模型还显示出较低的归一化均方根偏差（NRMSD），从 0.6698 % 到 1.8745 % 不等。估计光谱和模拟光谱之间的平均能量差（ΔE）始终保持在 0.01 千伏以下。这些结果与最近的研究结果相当，后者报告了更高的 NRMSD 和 ΔE。它的优点包括精度高、使用标准设备和算法值。虽然目前使用 13 个塞子已经足够，但加入不同密度的塞子可以提高精确度。该模型具有提高成像质量和优化临床应用中患者剂量的潜力。未来的趋势可能包括将能谱估算扩展到兆伏域，并整合 EPID 和 MVCT 等技术，以更好地预测高能光子束治疗中的剂量分布。

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引用次数: 0

Investigate potential clinical benefits and linear energy transfer sparing utilizing proton arc therapy for hepatocellular carcinoma 研究利用质子弧疗法治疗肝细胞癌的潜在临床优势和线性能量转移间隔

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2024-09-25 DOI: 10.1016/j.ejmp.2024.104816

Purpose

To investigate the potential clinical benefits and dose-averaged Linear Energy Transfer (LET_d) sparing, utilizing proton arc plan for hepatocellular carcinoma (HCC) patients in comparison with Intensity Modulated Proton Therapy (IMPT).

Methods

Ten HCC patients have been retrospectively selected. Two planning groups were created: Proton Arc plans using Monaco ver. 6 and the clinical IMPT plan. Both planning groups used the same robustness parameters. The prescription dose is 67.5 Gy (RBE) in 15 fractions of the Clinical Target Volume (CTV). Robustness evaluations were performed to ensure dose coverage. Normal Tissue Complicated Probability (NTCP) model was utilized to predict the possibility of Radiation-Induced Liver Disease (RILD) and evaluate the potential benefit of proton arc therapy. LET_d calculation and evaluation were performed as well.

Results

Proton arc plan has shown better dosimetric improvements of most Organ-At-Risks (OARs). More specifically, the liver mean dose has been significantly reduced from 14.7 GyE to 10.62 GyE compared to the IMPT plan. The predicted possibility of RILD has also been significantly reduced for cases with a large and deep liver target where healthy liver tissue sparing is a challenge. Additionally, proton arc therapy could increase the average LET_d in the target and reduce LET_d in adjacent OARs.

Conclusions

The potential clinical benefit of utilizing proton arc therapy HCC varies depending on the patient-specific geometry. With more freedom, proton arc therapy can offer a better dosimetric plan quality in the challenge cases, which might not be feasible using the current IMPT technique.

目的研究利用质子弧计划治疗肝细胞癌（HCC）患者与调强质子疗法（IMPT）相比的潜在临床益处和剂量平均线性能量转移（LETd）疏导。建立了两组计划：使用 Monaco ver.6 版本的质子弧计划和临床 IMPT 计划。两组计划均使用相同的稳健性参数。处方剂量为 67.5 Gy (RBE)，临床靶体积 (CTV) 为 15 分。为确保剂量覆盖范围，进行了稳健性评估。正常组织并发症概率（NTCP）模型用于预测辐射诱发肝病（RILD）的可能性，并评估质子弧治疗的潜在益处。结果质子弧计划对大多数器官风险（OAR）的剂量学改善更好。更具体地说，与 IMPT 方案相比，肝脏的平均剂量从 14.7 GyE 大幅降至 10.62 GyE。对于肝脏靶点较大且较深的病例，预计发生 RILD 的可能性也大大降低，因为在这种情况下，保留健康的肝脏组织是一项挑战。此外，质子弧治疗可提高靶区的平均 LETd，降低邻近 OAR 的 LETd。质子弧治疗具有更大的自由度，可以为挑战病例提供更好的剂量测定计划质量，而目前的 IMPT 技术可能无法实现这一点。

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引用次数: 0

Development of a Monte Carlo simulation platform for the systematic evaluation of photon-counting detector-based micro-CT 开发蒙特卡洛模拟平台，用于系统评估基于光子计数探测器的微型计算机断层显微技术

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2024-09-25 DOI: 10.1016/j.ejmp.2024.104824

Purpose

This study aimed to develop a photon-counting detector (PCD) based micro-CT simulation platform for assessing the performance of three different PCD sensor materials: cadmium telluride (CdTe), gallium arsenide (GaAs), and silicon (Si). The evaluation encompasses the components of primary and scatter signals, performance of imaging contrast agents, and detector efficiency.

Methods

Simulations were performed using the Geant4 Monte Carlo toolkit, and a micro-PCD-CT system was meticulously modeled based on realistic geometric parameters. Results.

The simulation can obtain HU values consistent with measured results for iodine and calcium hydroxyapatite contrast agents. The two major components of scatter signals for CdTe and GaAs based PCD are fluorescent X-ray photons and photoelectrons, whereas for Si, the components are photoelectrons and Compton electrons. Scattering counts of CdTe and GaAs sensors can be effectively reduced by using energy thresholds, whereas those of Si sensor are insensitive to the applied threshold. The optimal threshold values for CdTe and GaAs are 30 and 15 keV, respectively. For contrast agent imaging, GaAs exhibits enhanced sensitivity to low photon energies compared to CdTe, while it’s contrast-to-noise ratio (CNR) values are slightly lower than those of CdTe at the same contrast agent concentration. Among the three sensor materials, Si has the lowest CNR and detector efficiency; CdTe exhibits the highest efficiency, except in low-energy ranges (< 45 keV), where GaAs has superior efficiency.

Conclusions

The proposed methods are expected to benefit PCD optimization and applications, including energy threshold selection, scattering correction, and may reduce the need for large-scale experiments.

目的本研究旨在开发一个基于光子计数探测器（PCD）的微型计算机断层扫描模拟平台，用于评估三种不同的PCD传感器材料：碲化镉（CdTe）、砷化镓（GaAs）和硅（Si）的性能。评估内容包括主信号和散射信号的成分、成像造影剂的性能以及探测器的效率。方法：使用 Geant4 Monte Carlo 工具包进行模拟，并根据现实的几何参数对微型 PCD-CT 系统进行了细致的建模。结果：模拟可获得与碘和羟基磷灰石钙造影剂测量结果一致的 HU 值。基于碲化镉和砷化镓的 PCD 散射信号的两个主要成分是荧光 X 射线光子和光电子，而对于硅，其成分是光电子和康普顿电子。使用能量阈值可以有效减少碲化镉和砷化镓传感器的散射计数，而硅传感器的散射计数对所使用的阈值不敏感。碲化镉和砷化镓的最佳阈值分别为 30 和 15 千伏。在造影剂成像方面，与碲化镉相比，砷化镓对低光子能量的灵敏度更高，但在相同的造影剂浓度下，其对比度-噪声比（CNR）值略低于碲化镉。在三种传感器材料中，硅的 CNR 和探测器效率最低；碲化镉的效率最高，但在低能量范围（45 keV）内，砷化镓的效率更高。

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引用次数: 0

Open LEARN: Open access linear accelerator education and augmented reality Navigator 开放 LEARN：开放式直线加速器教育和增强现实导航仪

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2024-09-13 DOI: 10.1016/j.ejmp.2024.104515

Purpose

To create an open-access Linear Accelerator Education and Augmented Reality Navigator (Open LEARN) via 3D printable objects and interactive augmented reality assets.

Methods

This study describes an augmented reality linear accelerator (linac) model accessible through a QR code and a smartphone to address the challenges of medical physics and radiation oncology trainees in low-to-middle-income countries.

Results

Major components of a generic linear accelerator are modeled as individual objects. These objects can be 3D printed for hands-on learning and used as interactive 3D assets within the augmented reality app. In the AR app, descriptions are displayed to navigate the components spatially and textually. Items modeled include the treatment couch, klystron, circulator, RF waveguides, electron gun, waveguide, beam steering assemblies, target, collimators, multi-leaf collimators, and imaging systems. The linear accelerator is rendered at nearly 100% of its actual size, allowing users to change magnification and view objects from different angles.

Conclusions

The augmented reality linear accelerators and 3D-printed objects make these complex machines easily accessible with smartphones and 3D-printing technologies, facilitating education and training through physical and virtual interaction.

目的通过三维打印对象和交互式增强现实资产，创建一个可开放访问的线性加速器教育和增强现实导航器（Open LEARN）。方法本研究描述了一个可通过二维码和智能手机访问的增强现实线性加速器（linac）模型，以解决中低收入国家医学物理和放射肿瘤学学员面临的挑战。这些物体可通过三维打印进行实践学习，并在增强现实应用程序中用作交互式三维资产。在增强现实应用程序中，将显示相关说明，以便在空间和文字上对组件进行导航。建模项目包括治疗床、速调管、循环器、射频波导、电子枪、波导、光束转向组件、靶、准直器、多叶准直器和成像系统。增强现实直线加速器和三维打印对象使这些复杂的机器可以通过智能手机和三维打印技术轻松访问，通过物理和虚拟互动促进教育和培训。

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引用次数: 0

SC14.04 ISODOSE-CONSTRAINED AUTOMATIC TREATMENT PLANNING WITH MULTICRITERIA RATING BASED ON PHYSICAL EVALUATION OF PREDICTED DOSE FOR NASOPHARYNGEAL CANCER SC14.04 基于物理评估鼻咽癌预测剂量的多标准评级的等剂量约束自动治疗规划

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2024-09-01 DOI: 10.1016/j.ejmp.2024.103484

引用次数: 0

SC22.03 COMPARISON OF BREAST POPULATION DOSE ESTIMATION BETWEEN OLD AND NEW DOSIMETRY FOR DIGITAL MAMMOGRAPHY (DM) AND DIGITAL BREAST TOMOSYNTHESIS (DBT) SC22.03 数字乳腺 X 射线照相术（DM）和数字乳腺断层合成术（DBT）新旧剂量测量法对乳腺群体剂量估算的比较

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2024-09-01 DOI: 10.1016/j.ejmp.2024.103513

引用次数: 0

SC20.07 STATUS OF DIAGNOSTIC RADIOLOGY MEDICAL PHYSICIST RECOGNITION: RESULTS OF A EUROPEAN SURVEY SC20.07 放射诊断医学物理学家的认可状况：欧洲调查的结果

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2024-09-01 DOI: 10.1016/j.ejmp.2024.103504

引用次数: 0

SC21.05 NOVEL SPHERICAL IN-BEAM PET SCANNER FOR ONLINE RANGE MONITORING IN SMALL ANIMAL RADIATION RESEARCH sc21.05 用于小动物辐射研究在线范围监测的新型球形束内宠物扫描仪

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2024-09-01 DOI: 10.1016/j.ejmp.2024.103509

引用次数: 0

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