Zeitschrift fur Medizinische Physik最新文献_第4页

Assessment of resolution and noise in magnetic resonance images reconstructed by data driven approaches 用数据驱动方法重建磁共振图像的分辨率和噪声评估

IF 4.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Zeitschrift fur Medizinische Physik

Pub Date : 2025-08-01 DOI: 10.1016/j.zemedi.2023.08.007

Jonas Kleineisel , Katja Lauer , Alfio Borzì , Thorsten A. Bley , Herbert Köstler , Tobias Wech

Introduction

Deep learning-based approaches are increasingly being used for the reconstruction of accelerated MRI scans. However, presented analyses are frequently lacking in-detail evaluation of basal measures like resolution or signal-to-noise ratio. To help closing this gap, spatially resolved maps of image resolution and noise enhancement (g-factor) are determined and assessed for typical model- and data-driven MR reconstruction methods in this paper.

Methods

MR data from a routine brain scan of a patient were undersampled in retrospect at R = 4 and reconstructed using two data-driven (variational network (VN), U-Net) and two model based reconstructions methods (GRAPPA, TV-constrained compressed sensing). Local resolution was estimated by the width of the main-lobe of a local point-spread function, which was determined for every single pixel by reconstructing images with an additional small perturbation. G-factor maps were determined using a multiple replica method.

Results

GRAPPA showed good spatial resolution, but increased g-factors (1.43–1.84, 75% quartile) over all other methods. The images delivered from compressed sensing suffered most from low local resolution, in particular in homogeneous areas of the image. VN and U-Net show similar resolution with mostly moderate local blurring, slightly better for U-Net. For all methods except GRAPPA the resolution as well as the g-factors depend on the anatomy and the direction of undersampling.

Conclusion

Objective image quality parameters, local resolution and g-factors have been determined. The examined data driven methods show less local blurring than compressed sensing. The noise enhancement for reconstructions using CS, VN and U-Net is elevated at anatomical contours but is drastically reduced with respect to GRAPPA. Overall, the applied framework provides the possibility for more detailed analysis of novel reconstruction approaches incorporating non-linear and non-stationary transformations.

基于深度学习的方法越来越多地被用于加速MRI扫描的重建。然而，目前的分析往往缺乏对分辨率或信噪比等基本指标的详细评估。为了帮助缩小这一差距，本文确定并评估了典型模型和数据驱动的MR重建方法的图像分辨率和噪声增强（g因子）的空间分辨图。方法对1例患者常规脑扫描的磁共振数据进行R = 4的欠采样，采用两种数据驱动（变分网络（VN）、U-Net）和两种基于模型的重构方法（GRAPPA、电视约束压缩感知）进行重构。局部分辨率是通过局部点扩散函数的主瓣宽度来估计的，该主瓣宽度是通过附加小扰动重建图像来确定的。使用多重复制方法确定g因子图。结果grappa具有良好的空间分辨率，但g因子（1.43 ~ 1.84,75%四分位数）高于其他三种方法。压缩感知传递的图像最容易受到低局部分辨率的影响，特别是在图像的均匀区域。VN和U-Net显示出相似的分辨率，大多是适度的局部模糊，U-Net稍微好一点。对于除GRAPPA外的所有方法，分辨率和g因子取决于解剖结构和欠采样方向。结论确定了客观的图像质量参数、局部分辨率和g因子。所研究的数据驱动方法比压缩感知显示更少的局部模糊。使用CS， VN和U-Net重建的噪声增强在解剖轮廓处升高，但相对于GRAPPA则大大降低。总的来说，应用框架为更详细地分析包含非线性和非平稳变换的新型重建方法提供了可能性。

{"title":"Assessment of resolution and noise in magnetic resonance images reconstructed by data driven approaches","authors":"Jonas Kleineisel , Katja Lauer , Alfio Borzì , Thorsten A. Bley , Herbert Köstler , Tobias Wech","doi":"10.1016/j.zemedi.2023.08.007","DOIUrl":"10.1016/j.zemedi.2023.08.007","url":null,"abstract":"<div><h3>Introduction</h3><div>Deep learning-based approaches are increasingly being used for the reconstruction of accelerated MRI scans. However, presented analyses are frequently lacking in-detail evaluation of basal measures like resolution or signal-to-noise ratio. To help closing this gap, spatially resolved maps of image resolution and noise enhancement (g-factor) are determined and assessed for typical model- and data-driven MR reconstruction methods in this paper.</div></div><div><h3>Methods</h3><div>MR data from a routine brain scan of a patient were undersampled in retrospect at R = 4 and reconstructed using two data-driven (variational network (VN), U-Net) and two model based reconstructions methods (GRAPPA, TV-constrained compressed sensing). Local resolution was estimated by the width of the main-lobe of a local point-spread function, which was determined for every single pixel by reconstructing images with an additional small perturbation. G-factor maps were determined using a multiple replica method.</div></div><div><h3>Results</h3><div>GRAPPA showed good spatial resolution, but increased g-factors (1.43–1.84, 75% quartile) over all other methods. The images delivered from compressed sensing suffered most from low local resolution, in particular in homogeneous areas of the image. VN and U-Net show similar resolution with mostly moderate local blurring, slightly better for U-Net. For all methods except GRAPPA the resolution as well as the g-factors depend on the anatomy and the direction of undersampling.</div></div><div><h3>Conclusion</h3><div>Objective image quality parameters, local resolution and g-factors have been determined. The examined data driven methods show less local blurring than compressed sensing. The noise enhancement for reconstructions using CS, VN and U-Net is elevated at anatomical contours but is drastically reduced with respect to GRAPPA. Overall, the applied framework provides the possibility for more detailed analysis of novel reconstruction approaches incorporating non-linear and non-stationary transformations.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 343-356"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10243559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Evaluation of 2D ion chamber arrays for patient specific quality assurance using a static phantom at a 0.35 T MR-Linac 在 0.35 T MR-Linac 上使用静态模型对二维离子室阵列进行患者特定质量保证评估。

IF 4.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Zeitschrift fur Medizinische Physik

Pub Date : 2025-08-01 DOI: 10.1016/j.zemedi.2023.12.003

C. Katharina Renkamp , Daniela Eulenstein , Moritz Sebald , Fabian Schlüter , Carolin Buchele , Carolin Rippke , Jürgen P. Debus , Sebastian Klüter

Introduction

Patient specific quality assurance (QA) in MR-Linacs can be performed with MR-compatible ion chamber arrays. However, the presence of a static magnetic field can alter the angular response of such arrays substantially. This works investigates the suitability of two ion chamber arrays, an air-filled and a liquid-filled array, for patient specific QA at a 0.35 T MR-Linac using a static phantom.

Methods

In order to study the angular response, the two arrays were placed in a static, solid phantom and irradiated with 9.96 × 9.96 cm² fields every 10° beam angle at a 0.35 T MR-Linac. Measurements were compared to the TPS calculated dose in terms of gamma passing rate and relative dose to the central chamber. 20 patient specific quality assurance plans were measured using the liquid-filled array.

Results

The air-filled array showed asymmetric angular response changes of central chamber dose of up to 18% and down to local 3 mm / 3% gamma rates of 20%, while only minor differences within 3% (excluding parallel irradiation and beams through the couch edges) were found for the liquid-filled ion chamber array without rotating the phantom. Patient plan QA using the liquid-filled array yielded a median local 3 mm / 3% 3D gamma passing rate of 99.8% (range 96.9%–100%).

Conclusion

A liquid-filled ionization chamber array in combination with a static phantom can be used for efficient patient specific plan QA in a single measurement set-up in a 0.35 T MR-Linac, while the air-filled ion chamber array phantom shows large angular response changes and has its limitations regarding patient specific QA measurements.

简介：MR-Linacs 中的患者特定质量保证（QA）可通过与 MR 兼容的离子室阵列来执行。然而，静态磁场的存在会大大改变此类阵列的角度响应。本研究利用静态模型研究了两种离子室阵列（充气和充液阵列）在 0.35 T MR-Linac 上进行患者特定 QA 的适用性：为了研究角度响应，将两个阵列置于静态实体模型中，在 0.35 T MR-Linac 上以每 10° 波束角照射 9.96 × 9.96 平方厘米的磁场。测量结果与 TPS 计算出的伽马通过率和中心腔相对剂量进行了比较。使用充液阵列测量了20个特定患者的质量保证计划：结果：充液阵列显示，中心腔剂量的不对称角度响应变化高达18%，局部3毫米/3%的伽马通过率为20%，而充液离子室阵列在不旋转模型的情况下，仅发现3%以内的微小差异（不包括平行照射和通过沙发边缘的光束）。使用充液阵列进行患者计划质量保证，局部 3 毫米/3%三维伽马通过率的中值为 99.8%（范围为 96.9%-100%）：充满液体的电离室阵列与静态模型相结合，可在 0.35 T MR-Linac 的单一测量装置中高效地进行特定患者计划 QA，而充满空气的电离室阵列模型会出现较大的角度响应变化，在特定患者 QA 测量方面有其局限性。

{"title":"Evaluation of 2D ion chamber arrays for patient specific quality assurance using a static phantom at a 0.35 T MR-Linac","authors":"C. Katharina Renkamp , Daniela Eulenstein , Moritz Sebald , Fabian Schlüter , Carolin Buchele , Carolin Rippke , Jürgen P. Debus , Sebastian Klüter","doi":"10.1016/j.zemedi.2023.12.003","DOIUrl":"10.1016/j.zemedi.2023.12.003","url":null,"abstract":"<div><h3>Introduction</h3><div>Patient specific quality assurance (QA) in MR-Linacs can be performed with MR-compatible ion chamber arrays. However, the presence of a static magnetic field can alter the angular response of such arrays substantially. This works investigates the suitability of two ion chamber arrays, an air-filled and a liquid-filled array, for patient specific QA at a 0.35 T MR-Linac using a static phantom.</div></div><div><h3>Methods</h3><div>In order to study the angular response, the two arrays were placed in a static, solid phantom and irradiated with 9.96 × 9.96 cm<sup>2</sup> fields every 10° beam angle at a 0.35 T MR-Linac. Measurements were compared to the TPS calculated dose in terms of gamma passing rate and relative dose to the central chamber. 20 patient specific quality assurance plans were measured using the liquid-filled array.</div></div><div><h3>Results</h3><div>The air-filled array showed asymmetric angular response changes of central chamber dose of up to 18% and down to local 3 mm / 3% gamma rates of 20%, while only minor differences within 3% (excluding parallel irradiation and beams through the couch edges) were found for the liquid-filled ion chamber array without rotating the phantom. Patient plan QA using the liquid-filled array yielded a median local 3 mm / 3% 3D gamma passing rate of 99.8% (range 96.9%–100%).</div></div><div><h3>Conclusion</h3><div>A liquid-filled ionization chamber array in combination with a static phantom can be used for efficient patient specific plan QA in a single measurement set-up in a 0.35 T MR-Linac, while the air-filled ion chamber array phantom shows large angular response changes and has its limitations regarding patient specific QA measurements.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 375-384"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139111420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Implementation and validation of 2-D-array based tests in routine linac quality assurance 在常规直列加速器质量保证中实施和验证基于二维阵列的测试。

IF 4.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Zeitschrift fur Medizinische Physik

Pub Date : 2025-08-01 DOI: 10.1016/j.zemedi.2024.01.006

Jiří Valenta, Manfred Schmidt, Christoph Bert

Purpose

In medical linac quality assurance (QA), to replace film dosimetry with low-resolution 2-D ionization chamber array measurements, to validate the procedures, and to perform a comprehensive sensitivity analysis.

Methods

A 2-D ionization chamber array with a spatial resolution of 7.62 mm was deployed to perform the following tests: Junction tests, MLC transmission test, beam profile constancy vs. gantry angle test, beam profile constancy vs. low dose delivery test, and beam energy constancy vs. low dose delivery test. Test validation and sensitivity analyses based on short- and long-term statistics of the test results were performed.

Results

All selected mechanical and dosimetry tests could be successfully performed with a 2-D array. Considering the tolerance limits recommended by the AAPM Task Group 142 report (2009), sensitivities of 99.0% or better and specificities ranging from 99.5% to 99.9% could be achieved in all tests when the proper metrics were chosen.

Conclusions

The results showed that a low-resolution 2-D ionization chamber array could replace film dosimetry without having to sacrifice high test sensitivity. Its implementation in the routine clinical linac QA program may involve considerable QA time savings.

目的：在医用直列加速器质量保证（QA）中，用低分辨率二维电离室阵列测量取代胶片剂量测定，验证程序，并进行全面的灵敏度分析：方法：使用空间分辨率为 7.62 毫米的二维电离室阵列进行以下测试：方法：部署了一个空间分辨率为 7.62 毫米的二维电离室阵列，进行了以下测试：结点测试、MLC 传输测试、光束剖面恒定性与龙门架角度测试、光束剖面恒定性与低剂量传输测试，以及光束能量恒定性与低剂量传输测试。根据测试结果的短期和长期统计数据，进行了测试验证和敏感性分析：结果：所有选定的机械和剂量测定测试都能通过二维阵列成功完成。考虑到 AAPM 第 142 工作组报告（2009 年）建议的容差限制，如果选择了适当的指标，所有测试的灵敏度都能达到 99.0% 或更高，特异度从 99.5% 到 99.9% 不等：结果表明，低分辨率二维电离室阵列可以取代胶片剂量测定，而无需牺牲高测试灵敏度。将其应用于常规临床直列加速器质量保证计划可能会大大节省质量保证时间。

{"title":"Implementation and validation of 2-D-array based tests in routine linac quality assurance","authors":"Jiří Valenta, Manfred Schmidt, Christoph Bert","doi":"10.1016/j.zemedi.2024.01.006","DOIUrl":"10.1016/j.zemedi.2024.01.006","url":null,"abstract":"<div><h3>Purpose</h3><div>In medical linac quality assurance (QA), to replace film dosimetry with low-resolution 2-D ionization chamber array measurements, to validate the procedures, and to perform a comprehensive sensitivity analysis.</div></div><div><h3>Methods</h3><div>A 2-D ionization chamber array with a spatial resolution of 7.62 mm was deployed to perform the following tests: Junction tests, MLC transmission test, beam profile constancy vs. gantry angle test, beam profile constancy vs. low dose delivery test, and beam energy constancy vs. low dose delivery test. Test validation and sensitivity analyses based on short- and long-term statistics of the test results were performed.</div></div><div><h3>Results</h3><div>All selected mechanical and dosimetry tests could be successfully performed with a 2-D array. Considering the tolerance limits recommended by the AAPM Task Group 142 report (2009), sensitivities of 99.0% or better and specificities ranging from 99.5% to 99.9% could be achieved in all tests when the proper metrics were chosen.</div></div><div><h3>Conclusions</h3><div>The results showed that a low-resolution 2-D ionization chamber array could replace film dosimetry without having to sacrifice high test sensitivity. Its implementation in the routine clinical linac QA program may involve considerable QA time savings.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 270-281"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139898425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Evaluation of RADIANCE Monte Carlo algorithm for treatment planning in electron based Intraoperative Radiotherapy (IOERT) 评估 RADIANCE 蒙地卡罗算法在基于电子的术中放疗（IOERT）中的治疗计划。

IF 4.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Zeitschrift fur Medizinische Physik

Pub Date : 2025-08-01 DOI: 10.1016/j.zemedi.2023.12.002

Charoula Iliaskou, Giulio Rossi, Ilias Sachpazidis, Vasilios Boronikolas, Mark Gainey, Dimos Baltas

Purpose

To perform experimental as well as independent Monte Carlo (MC) evaluation of the MC algorithm implemented in RADIANCE version 4.0.8, a dedicated treatment planning system (TPS) for 3D electron dose calculations in intraoperative radiation therapy (IOERT).

Methods and materials

The MOBETRON 2000 (IntraOp Medical Corporation, Sunnyvale, CA) IOERT accelerator was employed. PDD and profiles for five cylindrical plastic applicators with 50–90 mm diameter and 0°, 30° beveling were measured in a water phantom, at nominal energies of 6, 9 and 12 MeV. Additional PDD measurements were performed for all the energies without applicator. MC modeling of the MOBETRON was performed with the user code BEAMnrc and egs_chamber of the MC simulation toolkit EGSnrc. The generated phase space files of the two 0°-bevel applicators (50 mm, 80 mm) and three energies in both RADIANCE and BEAMnrc, were used to determine PDD and profiles in various set-ups of virtual water phantoms with air and bone inhomogeneities. 3D dose distributions were also calculated in image data sets of an anthropomorphic tissue-equivalent pelvis phantom. Image acquisitions were realized with a CT scanner (Philips Big Bore CT, Netherlands). Gamma analysis was applied to quantify the deviations of the RADIANCE calculations to the measurements and EGSnrc calculations. Gamma criteria normalized to the global maximum were investigated between 2%, 2 mm and 3%, 3 mm.

Results

RADIANCE MC calculations satisfied the gamma criteria of 3%, 3 mm with a tolerance limit of 85% passing rate compared to in- water phantom measurements, except for the dose profiles of the 30° beveled applicators. Mismatches lay in surface doses, in umbra regions and in the beveled end of the 30° applicators. A very good agreement to the EGSnrc calculations in heterogeneous media was observed. Deviations were more pronounced for the larger applicator diameter and higher electron energy. In 3D dose comparisons in the anthropomorphic phantom, gamma passing rates were higher than 96 % for both simulated applicators.

Conclusions

RADIANCE MC algorithm agrees within 3%, 3 mm criteria with in-water phantom measurements and EGSnrc MC dose distributions in heterogeneous media for 0°-bevel applicators. The user should be aware of missing scattering components and the 30° beveled applicators should be used with attention.

目的：对用于术中放射治疗（IOERT）三维电子剂量计算的专用治疗计划系统（TPS）RADIANCE 4.0.8版中实施的MC算法进行实验和独立蒙特卡洛（MC）评估：采用 MOBETRON 2000（IntraOp Medical Corporation，加利福尼亚州桑尼维尔市）IOERT 加速器。在标称能量为 6、9 和 12 MeV 时，在水模型中测量了直径为 50-90 毫米、斜角为 0°、30° 的五个圆柱形塑料涂抹器的 PDD 和轮廓。在不使用涂抹器的情况下，还对所有能量进行了额外的 PDD 测量。使用 MC 仿真工具包 EGSnrc 的用户代码 BEAMnrc 和 egs_chamber 对 MOBETRON 进行了 MC 建模。在 RADIANCE 和 BEAMnrc 中生成的两个 0° 斜面涂抹器（50 毫米和 80 毫米）和三种能量的相空间文件，被用于确定具有空气和骨骼不均匀性的虚拟水模型的各种设置中的 PDD 和剖面。此外，还计算了拟人组织等效骨盆模型图像数据集的三维剂量分布。图像采集是通过 CT 扫描仪（荷兰飞利浦大孔径 CT）实现的。伽马分析用于量化 RADIANCE 计算与测量和 EGSnrc 计算的偏差。伽马标准归一化为全局最大值，在 2%(2 mm)和 3%(3 mm)之间进行了研究：结果：RADIANCE MC 计算符合 3%, 3 mm 的伽马标准，与水模型测量结果相比，通过率误差限制在 85%，但 30° 斜面涂抹器的剂量曲线除外。在表面剂量、本影区域和 30° 斜面涂抹器的斜面端存在不匹配现象。在异质介质中，与 EGSnrc 计算结果的一致性非常好。当涂抹器直径越大、电子能量越高时，偏差越明显。在人体模型的三维剂量比较中，两种模拟涂抹器的伽马通过率均高于96%：结论：RADIANCE MC算法在3%、3 mm标准范围内与水中模型测量结果以及0°斜面施药器在异质介质中的EGSnrc MC剂量分布相吻合。用户应注意散射成分的缺失，并在使用 30° 斜面涂抹器时加以注意。

{"title":"Evaluation of RADIANCE Monte Carlo algorithm for treatment planning in electron based Intraoperative Radiotherapy (IOERT)","authors":"Charoula Iliaskou, Giulio Rossi, Ilias Sachpazidis, Vasilios Boronikolas, Mark Gainey, Dimos Baltas","doi":"10.1016/j.zemedi.2023.12.002","DOIUrl":"10.1016/j.zemedi.2023.12.002","url":null,"abstract":"<div><h3>Purpose</h3><div>To perform experimental as well as independent Monte Carlo (MC) evaluation of the MC algorithm implemented in RADIANCE version 4.0.8, a dedicated treatment planning system (TPS) for 3D electron dose calculations in intraoperative radiation therapy (IOERT).</div></div><div><h3>Methods and materials</h3><div>The MOBETRON 2000 (IntraOp Medical Corporation, Sunnyvale, CA) IOERT accelerator was employed. PDD and profiles for five cylindrical plastic applicators with 50–90 mm diameter and 0°, 30° beveling were measured in a water phantom, at nominal energies of 6, 9 and 12 MeV. Additional PDD measurements were performed for all the energies without applicator. MC modeling of the MOBETRON was performed with the user code BEAMnrc and egs_chamber of the MC simulation toolkit EGSnrc. The generated phase space files of the two 0°-bevel applicators (50 mm, 80 mm) and three energies in both RADIANCE and BEAMnrc, were used to determine PDD and profiles in various set-ups of virtual water phantoms with air and bone inhomogeneities. 3D dose distributions were also calculated in image data sets of an anthropomorphic tissue-equivalent pelvis phantom. Image acquisitions were realized with a CT scanner (Philips Big Bore CT, Netherlands). Gamma analysis was applied to quantify the deviations of the RADIANCE calculations to the measurements and EGSnrc calculations. Gamma criteria normalized to the global maximum were investigated between 2%, 2 mm and 3%, 3 mm.</div></div><div><h3>Results</h3><div>RADIANCE MC calculations satisfied the gamma criteria of 3%, 3 mm with a tolerance limit of 85% passing rate compared to in- water phantom measurements, except for the dose profiles of the 30° beveled applicators. Mismatches lay in surface doses, in umbra regions and in the beveled end of the 30° applicators. A very good agreement to the EGSnrc calculations in heterogeneous media was observed. Deviations were more pronounced for the larger applicator diameter and higher electron energy. In 3D dose comparisons in the anthropomorphic phantom, gamma passing rates were higher than 96 % for both simulated applicators.</div></div><div><h3>Conclusions</h3><div>RADIANCE MC algorithm agrees within 3%, 3 mm criteria with in-water phantom measurements and EGSnrc MC dose distributions in heterogeneous media for 0°-bevel applicators. The user should be aware of missing scattering components and the 30° beveled applicators should be used with attention.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 282-291"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139107067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Application of NEMA protocols to verify GATE models based on the Digital Biograph Vision and the Biograph Vision Quadra scanners 应用 NEMA 协议验证基于 Digital Biograph Vision 和 Biograph Vision Quadra 扫描仪的 GATE 模型。

IF 4.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Zeitschrift fur Medizinische Physik

Pub Date : 2025-08-01 DOI: 10.1016/j.zemedi.2024.01.005

Miriam Magela Peña-Acosta, Sergio Gallardo, María Lorduy-Alós, Gumersindo Verdú

Purpose

The Monte Carlo method is an effective tool to simulate and verify PET systems. Furthermore, it can help in the design and optimization of new medical imaging devices and algorithms. In this framework, the goal of this work is to verify the GATE toolkit performance when applied to simulate two Siemens Healthineers PET scanners: a standard axial field-of-view Biograph Vision scanner and the new long axial field-of-view Biograph Vision Quadra scanner.

Methods

The simulation toolkit GATE is based on GEANT4, comprising its main functionalities and a set of domain-specific features in the field of medical physics. To accomplish our purpose, the guidelines described in the NEMA NU 2-2018 protocol are reproduced. Then the simulated results are compared to experimental data available in the literature for both PET scanners. The assessment of the models includes different studies of sensitivity, count rate performances, spatial resolution and image quality. These tests are intended to evaluate the image quality of PET devices.

Results

In the spatial resolution test, relative errors lower than 8% are obtained between the experiments and GATE models. The sensitivity is 17.2 cps/kBq (Vision) and 175.9 cps/kBq (Quadra), representing relative differences with the experiment of 6% and 0.3%, respectively. Deviations from peak NECR are less than 9%. In the Image Quality test, the contrast recovery coefficient for hot spheres, with 8 iterations and 5 subsets, ranges between 57–83% for Vision and 54–86% for Quadra. These values represent a maximum deviation between the simulations and the experiments of 10% for the Quadra scanner. In the case of the Vision scanner, the highest difference is observed for the 10 mm sphere (∼38%) due to the higher contrast recovery of the experiment caused by the Gibbs artifact from the use of PSF reconstruction.

Conclusions

The results of the simulations have provided evidence of a good agreement between the experimental data and the results obtained with GATE. Thus, this work supports the capability of this MC toolkit to accurately simulate the models of the Vision and Quadra scanners. This study has laid the basis for further research in this field and has identified several areas that could be explored.

目的：蒙特卡罗方法是模拟和验证 PET 系统的有效工具。此外，它还有助于设计和优化新的医疗成像设备和算法。在此框架下，这项工作的目标是验证 GATE 工具包在模拟两台西门子医疗 PET 扫描仪时的性能：标准轴向视场 Biograph Vision 扫描仪和新型长轴向视场 Biograph Vision Quadra 扫描仪：模拟工具包 GATE 基于 GEANT4，包括其主要功能和一系列医学物理领域的特定功能。为了达到我们的目的，我们复制了 NEMA NU 2-2018 协议中描述的指南。然后将模拟结果与文献中关于这两种 PET 扫描仪的实验数据进行比较。对模型的评估包括对灵敏度、计数率性能、空间分辨率和图像质量的不同研究。这些测试旨在评估 PET 设备的图像质量：在空间分辨率测试中，实验与 GATE 模型之间的相对误差低于 8%。灵敏度为 17.2 cps/kBq（Vision）和 175.9 cps/kBq（Quadra），与实验的相对误差分别为 6% 和 0.3%。与 NECR 峰值的偏差小于 9%。在图像质量测试中，热球的对比度恢复系数在 8 次迭代和 5 个子集之间，Vision 为 57-83%，Quadra 为 54-86%。就 Quadra 扫描仪而言，这些数值代表模拟与实验之间的最大偏差为 10%。在 Vision 扫描仪中，10 毫米球体的差异最大（38%），原因是使用 PSF 重建时产生的 Gibbs 伪影导致实验对比度恢复较高：模拟结果证明，实验数据与使用 GATE 得出的结果非常吻合。因此，这项工作支持 MC 工具包准确模拟 Vision 和 Quadra 扫描仪模型的能力。这项研究为这一领域的进一步研究奠定了基础，并确定了几个可以探索的领域。

{"title":"Application of NEMA protocols to verify GATE models based on the Digital Biograph Vision and the Biograph Vision Quadra scanners","authors":"Miriam Magela Peña-Acosta, Sergio Gallardo, María Lorduy-Alós, Gumersindo Verdú","doi":"10.1016/j.zemedi.2024.01.005","DOIUrl":"10.1016/j.zemedi.2024.01.005","url":null,"abstract":"<div><h3>Purpose</h3><div>The Monte Carlo method is an effective tool to simulate and verify PET systems. Furthermore, it can help in the design and optimization of new medical imaging devices and algorithms. In this framework, the goal of this work is to verify the GATE toolkit performance when applied to simulate two Siemens Healthineers PET scanners: a standard axial field-of-view Biograph Vision scanner and the new long axial field-of-view Biograph Vision Quadra scanner.</div></div><div><h3>Methods</h3><div>The simulation toolkit GATE is based on GEANT4, comprising its main functionalities and a set of domain-specific features in the field of medical physics. To accomplish our purpose, the guidelines described in the NEMA NU 2-2018 protocol are reproduced. Then the simulated results are compared to experimental data available in the literature for both PET scanners. The assessment of the models includes different studies of sensitivity, count rate performances, spatial resolution and image quality. These tests are intended to evaluate the image quality of PET devices.</div></div><div><h3>Results</h3><div>In the spatial resolution test, relative errors lower than 8% are obtained between the experiments and GATE models. The sensitivity is 17.2 cps/kBq (Vision) and 175.9 cps/kBq (Quadra), representing relative differences with the experiment of 6% and 0.3%, respectively. Deviations from peak NECR are less than 9%. In the Image Quality test, the contrast recovery coefficient for hot spheres, with 8 iterations and 5 subsets, ranges between 57–83% for Vision and 54–86% for Quadra. These values represent a maximum deviation between the simulations and the experiments of 10% for the Quadra scanner. In the case of the Vision scanner, the highest difference is observed for the 10 mm sphere (∼38%) due to the higher contrast recovery of the experiment caused by the Gibbs artifact from the use of PSF reconstruction.</div></div><div><h3>Conclusions</h3><div>The results of the simulations have provided evidence of a good agreement between the experimental data and the results obtained with GATE. Thus, this work supports the capability of this MC toolkit to accurately simulate the models of the Vision and Quadra scanners. This study has laid the basis for further research in this field and has identified several areas that could be explored.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 318-330"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139716810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Impact of the maximum ring difference on image quality and noise characteristics of a total-body PET/CT scanner 最大环差对全身PET/CT扫描仪的图像质量和噪声特性的影响。

IF 4.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Zeitschrift fur Medizinische Physik

Pub Date : 2025-08-01 DOI: 10.1016/j.zemedi.2023.09.001

Fabian P. Schmidt , Julia G. Mannheim , Pia M. Linder , P. Will , Lena Sophie Kiefer , Maurizio M. Conti , Christian la Fougère , Ivo F. Rausch

The sensitivity of a PET system highly depends on the axial acceptance angle or maximum ring difference (MRD), which can be particularly high for total-body scanners due to their larger axial field of views (aFOVs). This study aims to evaluate the impact on image quality (IQ) and noise performance when MRD85 (18°), the current standard for clinical use, is increased to MRD322 (52°) for the Biograph Vision Quadra (Siemens Healthineers).

Methods

Studies with a cylindrical phantom covering the 106 cm aFOV and an IEC phantom filled with ¹⁸F, ⁶⁸Ga and ⁸⁹Zr were performed for acquisition times from 60 to 1800 s and activity concentrations from 0.4 to 3 kBq/ml to assess uniformity, contrast recovery coefficients (CRCs) and to characterize noise by coefficient of variation (CV). Spatial resolution was compared for both MRDs by sampling a quadrant of the FOV with a point source. Further IQ, CV, liver SUV_mean and SUV_max were compared for a cohort of 5 patients scanned with [¹⁸F]FDG (3 MBq/kg, 1 h p.i.) from 30 to 300 s.

Results

CV was improved by a factor of up to 1.49 and is highest for short acquisition times, peaks at the center field of view and mitigates parabolic in axial direction with no difference to MRD85 beyond the central 80 cm. No substantial differences between the two evaluated MRDs in regards to uniformity, SUV_mean or CRC for the different isotopes were observed. A degradation of the average spatial resolution of 0.9 ± 0.2 mm in the central 40 cm FOV was determined with MRD322. Depending on the acquisition time MRD322 resulted in a decrease of SUV_max between 23.8% (30 s) and 9.0% (300 s).

Conclusion

Patient and phantom studies revealed that scan time could be lowered by approximately a factor of two with MRD322 while maintaining similar noise performance. The moderate degradation in spatial resolution for MRD322 is worth to exploit the full potential of the Quadra by either shorten scan times or leverage noise performance in particular for low count scenarios such as ultra-late imaging or dynamic studies with high temporal resolution.

PET系统的灵敏度在很大程度上取决于轴向接受角或最大环差（MRD），由于其较大的轴向视场（aFOV），这对于全身扫描仪来说可能特别高。本研究旨在评估当前临床使用标准MRD85（18°）提高到Biograph-Vision Quadra（Siemens Healthineers）的MRD322（52°）时对图像质量（IQ）和噪声性能的影响 cm aFOV和填充18F、68Ga和89Zr的IEC体模的采集时间为60至1800 s和0.4-3的活性浓度 kBq/ml以评估均匀性、对比度恢复系数（CRC）并通过变异系数（CV）表征噪声。通过用点源对FOV的象限进行采样，比较了两种MRD的空间分辨率。进一步比较了5名接受[18F]FDG扫描的患者的IQ、CV、肝脏SUVmean和SUVmax（3 MBq/kg，1 h p.i.）从30到300 结果：CV提高了1.49倍，在短采集时间内最高，在中心视场处达到峰值，并缓解了轴向抛物线，与MRD85在中心80以外没有差异 在不同同位素的均匀性、SUVmean或CRC方面，两个评估的MRD之间没有观察到实质性差异。0.9的平均空间分辨率下降 ± 0.2 中心40毫米 cm FOV用MRD322测定。根据采集时间，MRD322导致SUVmax下降23.8%（30 s）和9.0%（300 s）结论：患者和体模研究表明，使用MRD322可以将扫描时间降低约两倍，同时保持类似的噪声性能。MRD322空间分辨率的适度降低值得通过缩短扫描时间或利用噪声性能来充分利用Quadra的潜力，特别是在低计数场景中，如超晚期成像或具有高时间分辨率的动态研究。

{"title":"Impact of the maximum ring difference on image quality and noise characteristics of a total-body PET/CT scanner","authors":"Fabian P. Schmidt , Julia G. Mannheim , Pia M. Linder , P. Will , Lena Sophie Kiefer , Maurizio M. Conti , Christian la Fougère , Ivo F. Rausch","doi":"10.1016/j.zemedi.2023.09.001","DOIUrl":"10.1016/j.zemedi.2023.09.001","url":null,"abstract":"<div><div>The sensitivity of a PET system highly depends on the axial acceptance angle or maximum ring difference (MRD), which can be particularly high for total-body scanners due to their larger axial field of views (aFOVs). This study aims to evaluate the impact on image quality (IQ) and noise performance when MRD85 (18°), the current standard for clinical use, is increased to MRD322 (52°) for the Biograph Vision Quadra (Siemens Healthineers).</div></div><div><h3>Methods</h3><div>Studies with a cylindrical phantom covering the 106 cm aFOV and an IEC phantom filled with <sup>18</sup>F, <sup>68</sup>Ga and <sup>89</sup>Zr were performed for acquisition times from 60 to 1800 s and activity concentrations from 0.4 to 3 kBq/ml to assess uniformity, contrast recovery coefficients (CRCs) and to characterize noise by coefficient of variation (CV). Spatial resolution was compared for both MRDs by sampling a quadrant of the FOV with a point source. Further IQ, CV, liver SUV<sub>mean</sub> and SUV<sub>max</sub> were compared for a cohort of 5 patients scanned with [<sup>18</sup>F]FDG (3 MBq/kg, 1 h p.i.) from 30 to 300 s.</div></div><div><h3>Results</h3><div>CV was improved by a factor of up to 1.49 and is highest for short acquisition times, peaks at the center field of view and mitigates parabolic in axial direction with no difference to MRD85 beyond the central 80 cm. No substantial differences between the two evaluated MRDs in regards to uniformity, SUV<sub>mean</sub> or CRC for the different isotopes were observed. A degradation of the average spatial resolution of 0.9 ± 0.2 mm in the central 40 cm FOV was determined with MRD322. Depending on the acquisition time MRD322 resulted in a decrease of SUV<sub>max</sub> between 23.8% (30 s) and 9.0% (300 s).</div></div><div><h3>Conclusion</h3><div>Patient and phantom studies revealed that scan time could be lowered by approximately a factor of two with MRD322 while maintaining similar noise performance. The moderate degradation in spatial resolution for MRD322 is worth to exploit the full potential of the Quadra by either shorten scan times or leverage noise performance in particular for low count scenarios such as ultra-late imaging or dynamic studies with high temporal resolution.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 292-303"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49695836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Radiation-induced double-strand breaks by internal ex vivo irradiation of lymphocytes: Validation of a Monte Carlo simulation model using GATE and Geant4-DNA 淋巴细胞体内外照射引起的辐射诱导双链断裂：使用GATE和Geant4-DNA的蒙特卡罗模拟模型的验证

IF 4.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Zeitschrift fur Medizinische Physik

Pub Date : 2025-08-01 DOI: 10.1016/j.zemedi.2023.07.007

Maikol Salas-Ramirez , Lydia Maigne , Giovanna Fois , Harry Scherthan , Michael Lassmann , Uta Eberlein

<div><div>This study describes a method to validate a radiation transport model that quantifies the number of DNA double-strand breaks (DSB) produced in the lymphocyte nucleus by internal <em>ex vivo</em> irradiation of whole blood with the radionuclides <sup>90</sup>Y, <sup>99m</sup>Tc, <sup>123</sup>I, <sup>131</sup>I, <sup>177</sup>Lu, <sup>223</sup>Ra, and <sup>225</sup>Ac in a test vial using the GATE/Geant4 code at the macroscopic level and the Geant4-DNA code at the microscopic level.</div></div><div><h3>Methods</h3><div>The simulation at the macroscopic level reproduces an 8 mL cylindrical water-equivalent medium contained in a vial that mimics the geometry for internal <em>ex vivo</em> blood irradiation. The lymphocytes were simulated as spheres of 3.75 µm radius randomly distributed, with a concentration of 125 spheres/mL. A phase-space actor was attached to each sphere to register all the entering particles. The simulation at the microscopic level for each radionuclide was performed using the Geant4-DNA tool kit, which includes the <em>clustering</em> example centered on a density-based spatial clustering of applications with noise (DBSCAN) algorithm. The irradiation source was constructed by generating a single phase space from the sum of all phase spaces. The lymphocyte nucleus was defined as a water sphere of a 3.1 µm radius. The absorbed dose coefficients for lymphocyte nuclei (d<sub>Lymph</sub>) were calculated and compared with macroscopic whole blood absorbed dose coefficients (d<sub>Blood</sub>). The DBSCAN algorithm was used to calculate the number of DSBs. Lastly, the number of DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (simulation) was compared with the number of radiation-induced foci per cell and absorbed dose (RIF∙cell<sup>−1</sup>∙mGy<sup>−1</sup>) provided by experimental data for gamma and beta emitting radionuclides. For alpha emitters, d<sub>Lymph</sub> and the number of α-tracks∙100 cell<sup>−1</sup>∙mGy<sup>−1</sup> and DSBs∙µm<sup>−1</sup> were calculated using experiment-based thresholds for the α-track lengths and DSBs/track values. The results were compared with the results of an <em>ex vivo</em> study with <sup>223</sup>Ra.</div></div><div><h3>Results</h3><div>The d<sub>Lymph</sub> values differed from the d<sub>Blood</sub> values by −1.0% (<sup>90</sup>Y), −5.2% (<sup>99m</sup>Tc), −22.3% (<sup>123</sup>I), 0.35% (<sup>131</sup>I), 2.4% (<sup>177</sup>Lu), −5.6% (<sup>223</sup>Ra) and −6.1% (<sup>225</sup>Ac). The number of DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> for each radionuclide was 0.014 DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (<sup>90</sup>Y), 0.016 DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (<sup>99m</sup>Tc), 0.013DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (<sup>123</sup>I), 0.012 DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (<sup>131</sup>I), and 0.012 DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (<sup>177</sup>Lu). These values agree very well with experimental data. The number of α-tracks∙100 cells<sup>−1</sup>

本研究描述了一种验证辐射传输模型的方法，该模型通过在测试瓶中使用GATE/Geant4编码宏观水平和Geant4-DNA编码，用放射性核素90Y、99mTc、123I、131I、177Lu、223Ra和225Ac对全血进行体外照射，量化淋巴细胞核中产生的DNA双链断裂（DSB）的数量。方法在宏观水平模拟8 mL圆柱形水当量介质，模拟体外血液辐照的几何形状。将淋巴细胞模拟成半径为3.75 µm的球体，随机分布，浓度为125 球/mL。在每个球体上附加一个相空间actor来记录所有进入的粒子。使用Geant4-DNA工具包对每种放射性核素进行微观水平的模拟，其中包括以基于密度的空间聚类应用噪声（DBSCAN）算法为中心的聚类示例。辐照源是由所有相空间的和生成一个单相空间构成的。淋巴细胞核定义为3.1 µm半径的水球。计算淋巴细胞核吸收剂量系数（dLymph），并与宏观全血吸收剂量系数（dBlood）进行比较。采用DBSCAN算法计算dsb个数。最后，将DSB∙cell−1∙mGy−1的数量（模拟）与实验数据提供的每个细胞的辐射诱导焦点数量和吸收剂量（RIF∙cell−1∙mGy−1）进行比较。对于α发射器，采用α-径长度和dsb /径值的实验阈值计算dLymph和α-径∙100 cell−1∙mGy−1和dsb∙µm−1的数量。结果与223Ra的离体研究结果进行了比较。结果dLymph值与dBlood值的差异分别为- 1.0% （90Y）、- 5.2% （99mTc）、- 22.3% （123I）、0.35% （131I）、2.4% （177Lu）、- 5.6% （223Ra）和- 6.1% （225Ac）。每种放射性核素的DSB∙cell - 1∙mGy - 1的数量分别为0.014 DSB∙cell - 1∙mGy - 1 （90Y）、0.016 DSB∙cell - 1∙mGy - 1 （99mTc）、0.013 DSB∙cell - 1∙mGy - 1 （123I）、0.012 DSB∙cell - 1∙mGy - 1 （131I）和0.012 DSB∙cell - 1∙mGy - 1 （177Lu）。这些数值与实验数据吻合得很好。223Ra和225Ac的α-tracks∙100 细胞−1∙mGy−1的数量分别为0.144个α-tracks∙100 细胞−1∙mGy−1和0.151个α-tracks∙100 细胞−1∙mGy−1。这些数值与实验数据吻合得很好。在223Ra和225Ac条件下，每微米α-径长DSB的线密度分别为11.13 ± 0.04 DSB/µm和10.86 ± 0.06 DSB/µm。结论本研究建立了一个模拟淋巴细胞核DNA DSB损伤的模型，并通过核医学诊断和治疗过程中常用的放射性核素对体外血液照射的实验数据进行了验证。

{"title":"Radiation-induced double-strand breaks by internal ex vivo irradiation of lymphocytes: Validation of a Monte Carlo simulation model using GATE and Geant4-DNA","authors":"Maikol Salas-Ramirez , Lydia Maigne , Giovanna Fois , Harry Scherthan , Michael Lassmann , Uta Eberlein","doi":"10.1016/j.zemedi.2023.07.007","DOIUrl":"10.1016/j.zemedi.2023.07.007","url":null,"abstract":"<div><div>This study describes a method to validate a radiation transport model that quantifies the number of DNA double-strand breaks (DSB) produced in the lymphocyte nucleus by internal <em>ex vivo</em> irradiation of whole blood with the radionuclides <sup>90</sup>Y, <sup>99m</sup>Tc, <sup>123</sup>I, <sup>131</sup>I, <sup>177</sup>Lu, <sup>223</sup>Ra, and <sup>225</sup>Ac in a test vial using the GATE/Geant4 code at the macroscopic level and the Geant4-DNA code at the microscopic level.</div></div><div><h3>Methods</h3><div>The simulation at the macroscopic level reproduces an 8 mL cylindrical water-equivalent medium contained in a vial that mimics the geometry for internal <em>ex vivo</em> blood irradiation. The lymphocytes were simulated as spheres of 3.75 µm radius randomly distributed, with a concentration of 125 spheres/mL. A phase-space actor was attached to each sphere to register all the entering particles. The simulation at the microscopic level for each radionuclide was performed using the Geant4-DNA tool kit, which includes the <em>clustering</em> example centered on a density-based spatial clustering of applications with noise (DBSCAN) algorithm. The irradiation source was constructed by generating a single phase space from the sum of all phase spaces. The lymphocyte nucleus was defined as a water sphere of a 3.1 µm radius. The absorbed dose coefficients for lymphocyte nuclei (d<sub>Lymph</sub>) were calculated and compared with macroscopic whole blood absorbed dose coefficients (d<sub>Blood</sub>). The DBSCAN algorithm was used to calculate the number of DSBs. Lastly, the number of DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (simulation) was compared with the number of radiation-induced foci per cell and absorbed dose (RIF∙cell<sup>−1</sup>∙mGy<sup>−1</sup>) provided by experimental data for gamma and beta emitting radionuclides. For alpha emitters, d<sub>Lymph</sub> and the number of α-tracks∙100 cell<sup>−1</sup>∙mGy<sup>−1</sup> and DSBs∙µm<sup>−1</sup> were calculated using experiment-based thresholds for the α-track lengths and DSBs/track values. The results were compared with the results of an <em>ex vivo</em> study with <sup>223</sup>Ra.</div></div><div><h3>Results</h3><div>The d<sub>Lymph</sub> values differed from the d<sub>Blood</sub> values by −1.0% (<sup>90</sup>Y), −5.2% (<sup>99m</sup>Tc), −22.3% (<sup>123</sup>I), 0.35% (<sup>131</sup>I), 2.4% (<sup>177</sup>Lu), −5.6% (<sup>223</sup>Ra) and −6.1% (<sup>225</sup>Ac). The number of DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> for each radionuclide was 0.014 DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (<sup>90</sup>Y), 0.016 DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (<sup>99m</sup>Tc), 0.013DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (<sup>123</sup>I), 0.012 DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (<sup>131</sup>I), and 0.012 DSB∙cell<sup>−1</sup>∙mGy<sup>−1</sup> (<sup>177</sup>Lu). These values agree very well with experimental data. The number of α-tracks∙100 cells<sup>−1</sup>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 235-247"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10088978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

MPE training in Germany – Perspectives of the next generation 德国的MPE培训——对下一代的展望。

IF 4.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Zeitschrift fur Medizinische Physik

Pub Date : 2025-08-01 DOI: 10.1016/j.zemedi.2025.07.001

Tim Felgenhauer, Laura Garajová, Jonas Meyer, Andre Karius

引用次数: 0

Generation, validation, and benchmarking of a commercial independent Monte Carlo calculation beam model for multi-target SRS 多目标SRS的商业独立蒙特卡罗计算光束模型的生成、验证和基准测试

IF 4.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Zeitschrift fur Medizinische Physik

Pub Date : 2025-08-01 DOI: 10.1016/j.zemedi.2023.08.004

Justus Adamson , Brett G. Erickson , Chunhao Wang , Yunfeng Cui , Markus Alber , John Kirkpatrick , Fang-Fang Yin

Background

Dosimetric validation of single isocenter multi-target radiosurgery plans is difficult due to conditions of electronic disequilibrium and the simultaneous irradiation of multiple off-axis lesions dispersed throughout the volume. Here we report the benchmarking of a customizable Monte Carlo secondary dose calculation algorithm specific for multi-target radiosurgery which future users may use to guide their commissioning and clinical implementation.

Purpose

To report the generation, validation, and clinical benchmarking of a volumetric Monte Carlo (MC) dose calculation beam model for single isocenter radiosurgery of intracranial multi-focal disease.

Methods

The beam model was prepared within SciMoCa (ScientificRT, Munich Germany), a commercial independent dose calculation software, with the aim of broad availability via the commercial software for use with single isocenter radiosurgery. The process included (1) definition & acquisition of measurement data required for beam modeling, (2) tuning model parameters to match measurements, (3) validation of the beam model via independent measurements and end-to-end testing, and finally, (4) clinical benchmarking and validation of beam model utility in a patient specific QA setting. We utilized a 6X Flattening-Filter-Free photon beam from a TrueBeam STX linear accelerator (Siemens Healthineers, Munich Germany).

Results

In addition to the measured data required for standard IMRT/VMAT (depth dose, central axis profiles & output factors, leaf gap), beam modeling and validation for single-isocenter SRS required central axis and off axis (5 cm & 9 cm) small field output factors and comparison between measurement and simulation of backscatter with aperture for jaw much greater than MLCs. Validation end-to-end measurements included SRS MapCHECK in StereoPHAN geometry (2%/1 mm Gamma = 99.2% ± 2.2%), and OSL & scintillator measurements in anthropomorphic STEEV phantom (6 targets, volume = 0.1–4.1cc, distance from isocenter = 1.2–7.9 cm) for which mean difference was −1.9% ± 2.2%. For 10 patient cases, MC for individual PTVs was −0.8% ± 1.5%, −1.3% ± 1.7%, and −0.5% ± 1.8% for mean dose, D_95%, and D_1%, respectively. This corresponded to custom passing rates action limits per AAPM TG-218 guidelines of ±5.2%, ±6.4%, and ±6.3%, respectively.

Conclusions

The beam modeling, validation, and clinical action criteria outlined here serves as a benchmark for future users of the customized beam model within SciMoCa for single isocenter radiosurgery of multi-focal disease.

背景：由于电子不平衡和分散在整个体积内的多个离轴病变同时照射的条件，单个等中心多靶点放射手术计划的剂量学验证是困难的。在这里，我们报告了针对多靶点放射手术的可定制蒙特卡罗二次剂量计算算法的基准测试，未来的用户可以使用该算法来指导他们的调试和临床实施。目的报道颅内多灶性疾病单次等中心放射治疗的体积蒙特卡罗（MC）剂量计算束模型的建立、验证和临床基准。方法使用商业独立剂量计算软件SciMoCa （ScientificRT, Munich Germany）制备光束模型，目的是通过商业软件广泛应用于单等中心放射手术。该过程包括(1)定义和获取光束建模所需的测量数据，(2)调整模型参数以匹配测量结果，(3)通过独立测量和端到端测试验证光束模型，最后，(4)临床基准测试和验证光束模型在患者特定QA设置中的实用性。我们使用了来自TrueBeam STX线性加速器（Siemens Healthineers, Munich Germany）的6倍无平坦滤波光子束。结果除了标准IMRT/VMAT所需的测量数据（深度剂量、中心轴轮廓和输出因子、叶片间隙）外，单等中心SRS的光束建模和验证还需要中心轴和离轴（5 cm和9 cm）小场输出因子以及下颌孔径远大于MLCs的后向散射的测量和模拟比较。验证端到端测量包括SRS MapCHECK StereoPHAN几何(2% / 1 mm伽马 = 99.2% ± 2.2%),和OSL,闪烁体测量拟人化STEEV幻影(6个目标,体积 = 0.1 - -4.1 cc,距离等深点 = 1.2 -7.9 厘米)的平均差 −1.9%± 2.2%。在10例患者中，平均剂量、D95%和D1%中，单个PTVs的MC分别为- 0.8% ± 1.5%、- 1.3% ± 1.7%和- 0.5% ± 1.8%。这与AAPM TG-218指南规定的自定义合格率行动限制分别为±5.2%，±6.4%和±6.3%相对应。结论本文概述的光束建模、验证和临床作用标准为未来使用SciMoCa内的定制光束模型进行多灶性疾病的单中心放射手术提供了基准。

{"title":"Generation, validation, and benchmarking of a commercial independent Monte Carlo calculation beam model for multi-target SRS","authors":"Justus Adamson , Brett G. Erickson , Chunhao Wang , Yunfeng Cui , Markus Alber , John Kirkpatrick , Fang-Fang Yin","doi":"10.1016/j.zemedi.2023.08.004","DOIUrl":"10.1016/j.zemedi.2023.08.004","url":null,"abstract":"<div><h3>Background</h3><div>Dosimetric validation of single isocenter multi-target radiosurgery plans is difficult due to conditions of electronic disequilibrium and the simultaneous irradiation of multiple off-axis lesions dispersed throughout the volume. Here we report the benchmarking of a customizable Monte Carlo secondary dose calculation algorithm specific for multi-target radiosurgery which future users may use to guide their commissioning and clinical implementation.</div></div><div><h3>Purpose</h3><div>To report the generation, validation, and clinical benchmarking of a volumetric Monte Carlo (MC) dose calculation beam model for single isocenter radiosurgery of intracranial multi-focal disease.</div></div><div><h3>Methods</h3><div>The beam model was prepared within SciMoCa (ScientificRT, Munich Germany), a commercial independent dose calculation software, with the aim of broad availability via the commercial software for use with single isocenter radiosurgery. The process included (1) definition & acquisition of measurement data required for beam modeling, (2) tuning model parameters to match measurements, (3) validation of the beam model via independent measurements and end-to-end testing, and finally, (4) clinical benchmarking and validation of beam model utility in a patient specific QA setting. We utilized a 6X Flattening-Filter-Free photon beam from a TrueBeam STX linear accelerator (Siemens Healthineers, Munich Germany).</div></div><div><h3>Results</h3><div>In addition to the measured data required for standard IMRT/VMAT (depth dose, central axis profiles & output factors, leaf gap), beam modeling and validation for single-isocenter SRS required central axis and off axis (5 cm & 9 cm) small field output factors and comparison between measurement and simulation of backscatter with aperture for jaw much greater than MLCs. Validation end-to-end measurements included SRS MapCHECK in StereoPHAN geometry (2%/1 mm Gamma = 99.2% ± 2.2%), and OSL & scintillator measurements in anthropomorphic STEEV phantom (6 targets, volume = 0.1–4.1cc, distance from isocenter = 1.2–7.9 cm) for which mean difference was −1.9% ± 2.2%. For 10 patient cases, MC for individual PTVs was −0.8% ± 1.5%, −1.3% ± 1.7%, and −0.5% ± 1.8% for mean dose, D<sub>95%</sub>, and D<sub>1%</sub>, respectively. This corresponded to custom passing rates action limits per AAPM TG-218 guidelines of ±5.2%, ±6.4%, and ±6.3%, respectively.</div></div><div><h3>Conclusions</h3><div>The beam modeling, validation, and clinical action criteria outlined here serves as a benchmark for future users of the customized beam model within SciMoCa for single isocenter radiosurgery of multi-focal disease.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 3","pages":"Pages 248-258"},"PeriodicalIF":4.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10192034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Editorial Board + Consulting Editorial Board 编辑委员会+咨询编辑委员会

IF 4.2 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Zeitschrift fur Medizinische Physik

Pub Date : 2025-08-01 DOI: 10.1016/S0939-3889(25)00095-9

引用次数: 0