Journal of Applied Clinical Medical Physics最新文献_第9页

Impact of acquisition and reconstruction parameters on quantitative accuracy in dual-layer spectral CT: A phantom study 采集和重建参数对双层光谱CT定量准确性的影响：一项幻象研究。

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics

Pub Date : 2025-12-15 DOI: 10.1002/acm2.70423

Lingxuan Leng, Qizhen Zhu, HuiYing Qu, Bing Zhou, Wenbo Li, Fuquan Zhang, Bo Yang, Jie Qiu

Purpose

This study aims to systematically evaluate the impact of different CT acquisition and reconstruction parameters on the accuracy of dual-layer spectral CT-based functional imaging, including effective atomic number (Z_eff) maps, relative electron density (RED) maps, and virtual monochromatic images (VMIs).

Methods

A standardized phantom equipped with various material inserts, including air, soft-tissue–equivalent, polymer, and bone-equivalent materials, was scanned using a dual-layer spectral CT system. The investigated acquisition and reconstruction parameters included tube voltage, tube current–time product (mAs), reconstruction thickness, pitch, and reconstruction filter. Quantitative accuracy was assessed for RED and Z_eff by comparison with manufacturer-provided reference values, using Bland–Altman analysis. Comparative analyses were performed between VMIs at 40, 70, and 100 keV and conventional CT (120 kVp single-energy reconstruction from the dual-layer system) by calculating the mean and standard deviation of Hounsfield units (HU) differences, to evaluate the dependence of CT number stability on acquisition and reconstruction parameters.

Results

Across all acquisition and reconstruction parameters, RED and Z_eff measurements remained accurate, with signed differences within 2.4% and 0.4%, respectively. Compared with conventional CT, VMIs demonstrated greater robustness to parameter change. At 70 keV, HU variations did not exceed 8 HU, whereas conventional CT exhibited deviations up to 118 HU. Low-energy VMIs (40 keV) showed greater variability, with a maximum difference of 27 HU. Among the investigated parameters, tube voltage exerted the most evident influence.

Conclusion

Dual-layer spectral CT demonstrated quantitative accuracy in functional imaging (ED, Z_eff, and VMIs) across diverse acquisition and reconstruction parameters.

目的：本研究旨在系统评估不同CT采集和重建参数对双层光谱CT功能成像精度的影响，包括有效原子序数（Zeff）图、相对电子密度（RED）图和虚拟单色图像（VMIs）。方法：采用双层光谱CT系统扫描一个标准化的假体，植入各种材料，包括空气、软组织等效材料、聚合物和骨等效材料。研究的采集和重构参数包括管电压、管电流时间积（mAs）、重构厚度、节距和重构滤波器。通过与制造商提供的参考值进行比较，使用Bland-Altman分析来评估RED和Zeff的定量准确性。通过计算Hounsfield单位（HU）差值的均值和标准差，将40、70和100 keV下的VMIs与常规CT （120 kVp双层系统单能量重建）进行对比分析，以评估CT数稳定性对采集和重建参数的依赖性。结果：在所有采集和重建参数中，RED和Zeff测量值保持准确，其符号差异分别在2.4%和0.4%以内。与常规CT相比，VMIs对参数变化具有更强的鲁棒性。在70 keV下，HU变化不超过8 HU，而常规CT的偏差可达118 HU。低能量vmi （40 keV）表现出更大的变异性，最大差异为27 HU。在研究的参数中，管电压的影响最为明显。结论：双层光谱CT在不同采集和重建参数的功能成像（ED、Zeff和VMIs）中表现出定量准确性。

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引用次数: 0

Correction to: “Quantitative patient-specific quality assurance prediction using MLC mean leaf gap and PTV volume” 修正：“使用MLC平均叶间隙和PTV体积定量预测患者特异性质量保证”

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics

Pub Date : 2025-12-15 DOI: 10.1002/acm2.70412

Mills MD. Quantitative patient-specific quality assurance prediction using MLC mean leaf gap and PTV volume. J Appl Clin Med Phys. 2025;e70412. https://doi.org/10.1002/acm2.70146

The original article was incorrectly published as an Announcement. The article should have been published as a Research Article. The online version of this article has been corrected accordingly.

使用MLC平均叶间隙和PTV体积定量的患者特异性质量保证预测。中华临床医学杂志，2015;e70412。https://doi.org/10.1002/acm2.70146The原文被错误地作为公告发布。这篇文章应该作为研究论文发表。本文的在线版本已进行了相应的更正。

引用次数: 0

Adult brain T1 and T2 values measured at 3 T using magnetic resonance fingerprinting with phantom validation 成人大脑T1和T2值测量在3t时使用磁共振指纹与幻影验证。

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics

Pub Date : 2025-12-15 DOI: 10.1002/acm2.70289

Kalina V. Jordanova, Stephen E. Ogier, Stephen E. Russek, Cassandra M. Stoffer, Karl F. Stupic, Guido Buonincontri, Mathias Nittka, Kathryn E. Keenan

Background

For clinical implementation of quantitative MRI methods, it is necessary to understand the expected range of nominally healthy tissue properties. Additionally, to compare measurements across MRI systems or provide guidance for clinically meaningful change, these nominally healthy measurements should be completed with phantom validation of the measurement system and method.

Purpose

To measure T1 and T2 relaxation times on 20 participants using magnetic resonance fingerprinting (MRF) concurrently with phantom measurements for validation.

Methods

T1 and T2 relaxation times were measured at 3 T using MRF on 20 participants. To assess longitudinal reproducibility, a phantom was scanned in the same session as each in vivo measurement, which resulted in 11 phantom measurements over the 99-day study duration. At each imaging session, phantom and in vivo test-retest measurements were made. Phantom test-retest repeatability was evaluated along with longitudinal reproducibility. Additionally, in vivo test-retest repeatability was evaluated for brain regions of various sizes, and mean in vivo measurements for cerebrospinal fluid (CSF), gray matter (GM), and white matter (WM) are presented.

Results

Over the study duration, phantom measurements were repeatable and reproducible, and no changes were detected in the MRF measurement of T1 and T2 relaxation times on this system. For in vivo measurements, test-retest variation for CSF, GM, and WM was 2.3%, 0.31%, 0.57% for T1 and 8.3%, 1.9%, 1.3% for T2. We observed that the test-retest variation of T1 and T2 measurements increased as the segmented volume fell below 1 cm³. Mean and standard deviation of T1 and T2 were calculated over all participants for CSF, GM, and WM.

Conclusions

Phantom measurements characterized the measurement accuracy, repeatability, and reproducibility throughout the study. The MRF T1 and T2 measurements of normal brain tissues at 3 T are validated through concurrent phantom measurements, and mean values were reported for each tissue. This study provides one data point to answer the question of how often phantom quality assessment must be done in tandem with in vivo measurements.

背景：为了临床实施定量MRI方法，有必要了解名义上健康组织特性的预期范围。此外，为了比较不同MRI系统的测量结果或为临床有意义的变化提供指导，这些名义上健康的测量应该通过对测量系统和方法的虚幻验证来完成。目的：对20名被试的T1和T2弛豫时间进行磁共振指纹识别（MRF）和幻像测量相结合的验证。方法：采用磁共振成像技术测量20例被试在3 T时T1和T2的弛豫时间。为了评估纵向再现性，在每次体内测量的同一时间扫描一个幻体，在99天的研究期间进行了11次幻体测量。在每个成像阶段，进行幻体和体内测试-重测测量。幻影测试-重测重复性与纵向重复性一起进行评估。此外，对不同大小的脑区域进行了体内测试-重复测试的可重复性评估，并给出了脑脊液（CSF）、灰质（GM）和白质（WM）的体内平均测量值。结果：在研究期间，幻像测量是可重复和可再现的，并且在该系统上测量的T1和T2弛豫时间没有变化。对于体内测量，T1时CSF、GM和WM的重测变异为2.3%、0.31%、0.57%，T2时为8.3%、1.9%、1.3%。我们观察到T1和T2测量的重测变异随着分割体积低于1 cm3而增加。计算所有受试者的CSF、GM和WM的T1和T2的均值和标准差。结论：在整个研究过程中，幻影测量具有测量准确性、可重复性和再现性的特点。正常脑组织在3t时的MRF T1和T2测量通过并发幻像测量进行验证，并报告每个组织的平均值。这项研究提供了一个数据点来回答幽灵质量评估必须与体内测量同时进行的频率问题。

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引用次数: 0

Establishing a global medical physics graduate clinical training and development program in Ghana: A model for global health international education and collaboration 在加纳建立全球医学物理研究生临床培训和发展计划：全球卫生国际教育和合作的典范。

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics

Pub Date : 2025-12-15 DOI: 10.1002/acm2.70410

Shannon E. O'Reilly, Stephen Avery, Lyna Dinh, Andrew Friberg, Ayoola Okuribido, Eric K. Addison, Stephen Inkoom, Alhassan Mohammed Baidoo, Samuel Nii Tagoe, Elsie Effah Kaufmann, Sonya Gwak, Megan L. Doherty, Edem Sosu, Beatrice Wiafe Addai, Francis Hasford

Purpose

The Global Medical Physics Training and Development Program (GMPTDP) is a novel initiative that provides United States (US)-based graduate students in medical physics with structured, immersive clinical training in Ghana.

Methods

The five-week program begins with a cultural and clinical orientation in the US, followed by 4 weeks of clinical rotations across leading Ghanaian medical institutions. During rotations, students gain experience with teletherapy (LINACs and cobalt-60), brachytherapy, treatment planning, imaging, and more. Trainees participate in clinical activities, conduct collaborative projects, and engage in community outreach and cultural immersion. The program culminates in a symposium highlighting student experiences and future directions with speakers including physicists, oncologists, engineers, and policymakers.

Results

The pilot year of the program was successfully completed by three students from May 28 2024–July 2 2024. This article outlines the development, structure, and implementation of GMPTDP as a replicable model for global health training in medical physics, emphasizing sustainable partnerships between high-income and low- and middle-income countries. Educational objectives include demonstrating effective cross-border training models, fostering collaborative research, and expanding global clinical experience in the field of medical physics.

Conclusions

A model for a global medical physics training program was developed and successfully implemented.

目的：全球医学物理学培训和发展计划（GMPTDP）是一项新颖的倡议，为美国医学物理学研究生在加纳提供结构化的沉浸式临床培训。方法：为期五周的项目从美国的文化和临床导向开始，随后在加纳领先的医疗机构进行为期四周的临床轮岗。在轮岗期间，学生获得远程治疗（LINACs和钴-60）、近距离治疗、治疗计划、成像等方面的经验。学员参加临床活动，开展合作项目，并参与社区外展和文化沉浸。该计划的高潮是一个研讨会，突出学生的经历和未来的方向，演讲者包括物理学家、肿瘤学家、工程师和政策制定者。结果：从2024年5月28日至2024年7月2日，三名学生成功完成了该计划的试点年。本文概述了GMPTDP的发展、结构和实施，将其作为医学物理学全球卫生培训的可复制模式，强调高收入国家与中低收入国家之间的可持续伙伴关系。教育目标包括展示有效的跨境培训模式，促进合作研究，扩大医学物理领域的全球临床经验。结论：开发并成功实施了一个全球医学物理培训项目模型。

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引用次数: 0

Clinical application of cone beam CT in intensity-modulated radiotherapy for the moderate to severe thyroid-associated ophthalmopathy 锥束CT在中重度甲状腺相关性眼病调强放疗中的临床应用

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics

Pub Date : 2025-12-12 DOI: 10.1002/acm2.70416

Dan Kang, Hao Hu, Shuyun Ma, Shizhen Bin

<div> <section> <h3> Background</h3> <p>Cone beam CT (CBCT) has been reported for intensity-modulated radiation therapy (IMRT) of various cancers due to its real-time imaging capabilities, but studies on its application in orbital diseases, particularly moderate to severe thyroid-associated ophthalmopathy (TAO), remain limited.</p> </section> <section> <h3> Purpose</h3> <p>To investigate the clinical applications of CBCT in IMRT for TAO, with a focus on setup accuracy, dosimetric impact, and short-term changes in eye prominence.</p> </section> <section> <h3> Methods</h3> <p>A total of 115 CBCT scans from 17 TAO patients were analyzed. Pretreatment CBCT scans were registered to the planning CT using bony anatomy. The resulting setup errors were quantified in three translational directions. Residual shifts after online correction were tracked to assess interfractional variation and trends throughout the treatment course. Dose-volume histogram from plans recalculated with simulated setup errors (mean and maximum values) were compared to the original plan. Eye prominence was measured on serial CBCT scans, and its correlation with cumulative dose was analyzed.</p> </section> <section> <h3> Results</h3> <p>Mean setup errors were (–0.16 ± 1.09) mm, (–0.19 ± 1.18) mm, and (–0.55 ± 1.05) mm in X, Y, and Z directions. Errors significantly decreased planning target volume (PTV) conformity (<i>p</i> < 0.05) and increased <i>D</i><sub>mean</sub>, <i>D</i><sub>max</sub>, <i>D</i><sub>2%,</sub> and <i>D</i><sub>50%</sub> (<i>p</i> < 0.05). For organs at risk (OARs), maximum and mean doses increased, with left lens <i>D</i><sub>max</sub> increasing by 21.3%, 32.7%, 33.8%, and 13.2% for mean setup errors and X, Y, and Z maximum errors. Right lens showed similar increases. A correlation between CBCT-measured eye prominence and total radiotherapy dose was observed, with the binomial fit: y = 22.43 <b>+</b> 0.12x − (9.94 × 10<sup>−3</sup>) x<sup>2</sup> (<i>R<sup>2</sup></i> = 0.96). Mean eye prominence decreased significantly from (21.74 ± 1.74) mm pre-treatment to (20.94 ± 1.73) mm after 18 Gy of IMRT (<i>p</i> < 0.05).</p> </section> <section> <h3> Conclusion</h3> <p>CBCT image guidance for IMRT in moderate to severe TAO improves target conformity and coverage while reducing OAR doses, particularly for lenses. CBCT also shows promise for short-term efficacy assessment of eye prominence in radiotherapy patients which may alleviate patient anxiety with preli

由于其实时成像能力，锥束CT （CBCT）已被报道用于各种癌症的调强放射治疗（IMRT），但其在眼眶疾病，特别是中重度甲状腺相关性眼病（TAO）中的应用研究仍然有限。目的探讨CBCT在TAO的IMRT中的临床应用，重点关注设置准确性、剂量学影响和眼突出的短期变化。方法对17例TAO患者115例CBCT扫描结果进行分析。使用骨解剖将预处理CBCT扫描记录到计划CT上。由此产生的设置误差在三个平移方向上量化。跟踪在线校正后的剩余位移，以评估整个治疗过程中分数间的变化和趋势。通过模拟设置误差（平均值和最大值）重新计算的计划的剂量-体积直方图与原始计划进行比较。通过连续CBCT扫描测量眼突出，并分析其与累积剂量的相关性。结果X、Y、Z方向平均设置误差分别为（-0.16±1.09）mm、（-0.19±1.18）mm和（-0.55±1.05）mm。误差显著降低了计划目标体积（PTV）符合性（p < 0.05），提高了Dmean、Dmax、D2%和D50% （p < 0.05）。对于危险器官（OARs），最大和平均剂量增加，平均设置误差和X， Y和Z最大误差的左晶状体Dmax分别增加21.3%,32.7%，33.8%和13.2%。右晶状体也有类似的增加。观察到cbct测量的眼突出与放射治疗总剂量之间的相关性，二项拟合：y = 22.43 + 0.12x−(9.94 × 10−3)x2 （R2 = 0.96）。平均眼突由治疗前的（21.74±1.74）mm显著降低至18 Gy IMRT后的（20.94±1.73）mm （p < 0.05）。结论CBCT图像引导在中重度TAO的IMRT中提高了靶的符合性和覆盖率，同时减少了OAR的剂量，特别是透镜。CBCT也有望用于放疗患者眼突出的短期疗效评估，可以缓解患者的焦虑，从而提高患者对放疗的依从性。

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引用次数: 0

An all-in-one workflow for emergency hippocampal-avoidance whole-brain radiotherapy in brain metastases, with optional online adaptive extension 一个一体化的工作流程，用于脑转移的紧急海马回避全脑放疗，具有可选的在线自适应扩展

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics

Pub Date : 2025-12-12 DOI: 10.1002/acm2.70405

Haibo Peng, Yangang Zhou, Min Xie, Xuegui Ju, Ningyue Xu, Dong Gao, Lecheng Jia, Chunyan Dai, Huigang Tan, Tao Ren

<div> <section> <h3> Background</h3> <p>Brain metastases (BMs), among the most prevalent intracranial malignant tumors, frequently induce acute symptoms such as headaches and motor deficits due to elevated intracranial pressure. Although hippocampal-avoidance whole brain radiotherapy (HA-WBRT) has demonstrated superior preservation of cognitive function compared to standard WBRT—despite comparable intracranial progression-free survival and overall survival outcomes—its clinical application remains restricted by the complexity and time-intensive nature of conventional planning and delivery protocols. These limitations hinder its utility as an emergent intervention for patients requiring urgent symptom relief.</p> </section> <section> <h3> Purpose</h3> <p>To address this challenge, we developed a novel HA-WBRT-specific all-in-one (AIO) radiotherapy integrated with online adaptive techniques, and systematically evaluated its operational feasibility, dosimetric precision, and therapeutic effectiveness for emergency HA-WBRT in patients with BMs through preliminary clinical outcomes and related findings.</p> </section> <section> <h3> Methods</h3> <p>The HA-WBRT-specific AIO workflow featured by rapid auto-segmentation of the target and hippocampal, HA-constrained planning using volumetric modulated arc therapy (VMAT) with three coplanar lock-field full arcs ache ensuring a high first-pass success rate for treatment plans, and real-time in vivo quality assurance (QA) enabling safe beam delivery without delay was applied to the eleven emergency patients with BMs receiving HA-WBRT during their initial treatment fraction. Rotational setup errors in subsequent fractions were documented. For these fractions, online adaptive radiotherapy (ART) was implemented using the AIO-generated plan as the baseline. Time requirements for each workflow step and in vivo 3D gamma passing rates were analyzed to evaluate efficiency and dosimetric accuracy. Dosimetric differences between the ART-optimized plan (ART-Plan) and the image-guided radiotherapy plan (IGRT-Plan) were compared to quantify the impact of rotational deviations on dose distribution. Cognitive function (via the Mini-Mental State Examination [MMSE]) and functional independence (via the Basic Activities of Daily Living, BADL) were assessed before and after radiotherapy.</p> </section> <section> <h3> Results</h3> <p>The average duration of the AIO radiotherapy was 24.3 ± 0.6 min. The majority of AIO-Plan parameters satisfied RTOG 0933 criteria. For the AIO-Plans, in vivo 3D γ pass rates exceeded 94% (3 mm/3% gam

脑转移瘤（Brain metastasis, BMs）是最常见的颅内恶性肿瘤之一，常因颅内压升高而引起急性症状，如头痛和运动障碍。尽管海马回避全脑放疗（HA-WBRT）与标准的全脑放疗相比，在认知功能的保存方面表现出了更好的优势——尽管颅内无进展生存期和总生存期结果相当——但其临床应用仍然受到传统计划和交付方案的复杂性和时间密集性的限制。这些限制阻碍了其作为需要紧急症状缓解的患者的紧急干预的效用。为了应对这一挑战，我们开发了一种新型HA-WBRT特异性all-in-one （AIO）放疗，结合在线自适应技术，并通过初步临床结果和相关发现，系统评估了其在脑转移患者急诊HA-WBRT治疗中的操作可行性、剂量学精度和治疗效果。方法ha - wbrt特异性AIO工作流程具有快速自动分割目标和海马的特点，ha约束计划使用体积调制电弧治疗（VMAT），具有三个共面锁场全电弧，确保治疗计划的高首次通过成功率；实时体内质量保证（QA）使11名在初始治疗期间接受HA-WBRT治疗的脑转移患者能够无延迟地安全输送光束。记录了随后分数的旋转设置误差。对于这些部分，使用aio生成的计划作为基线实施在线适应性放疗（ART）。分析了每个工作步骤的时间要求和体内3D伽马通过率，以评估效率和剂量学准确性。比较art优化方案（ART-Plan）和影像引导放疗方案（IGRT-Plan）的剂量学差异，量化旋转偏差对剂量分布的影响。放疗前后分别评估患者的认知功能（通过迷你精神状态检查[MMSE]）和功能独立性（通过日常生活基本活动，BADL）。结果AIO放疗时间平均为24.3±0.6 min。大多数AIO-Plan参数满足RTOG 0933标准。对于AIO-Plans，体内3D γ通过率超过94% （3mm /3% γ标准，10%剂量阈值）。急诊患者记录的轮转错误表现出不规则和巨大的变化，突出了在线适应的必要性。值得注意的是，94%的馏分需要适应以满足NRG CC001规定的目标覆盖（TC）标准。所有ART-Plans显示3D γ通过率超过93% （3mm /3% γ标准，剂量阈值为10%）。ART平均持续时间为22.9±1.6 min。放疗后MMSE和BADL评分均有明显改善，急性症状得到有效控制和缓解。结论急诊脑转移患者的AIO工作流程是可行和安全的，有助于在第一次治疗期间迅速启动高效放疗，消除延误。随后的在线ART有效地纠正旋转偏差，确保足够的处方剂量覆盖目标体积，同时优化正常组织的剂量分配。HA-WBRT将AIO工作流程与在线适应相结合，显示了及时控制和缓解急性症状的潜力。

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引用次数: 0

Online adaptive MR-guided SBRT versus CT-based planning in pancreatic cancer: A single-center dosimetric comparative study 在线自适应磁共振引导的SBRT与基于ct的胰腺癌计划：单中心剂量学比较研究

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics

Pub Date : 2025-12-11 DOI: 10.1002/acm2.70391

Randa Kamel, Thierry Gevaert, Dirk Van den Berge, Mark De Ridder

Background

Stereotactic body radiotherapy (SBRT) for pancreatic cancer is limited by the proximity of tumors to gastrointestinal (GI) organs, increasing the risk of toxicity. Magnetic resonance-guided radiotherapy (MRgRT) offers potential advantages through superior soft tissue visualization, real-time tumor tracking, and online adaptive planning. This study aimed to quantitatively compare dosimetric outcomes of pancreatic cancer SBRT using online adaptive MRgRT versus conventional computed tomography-based image-guided radiotherapy (CT-IGRT).

Methods

A retrospective dosimetric analysis was conducted on 100 plans from 10 patients with primary (n = 3) or recurrent (n = 7) pancreatic adenocarcinoma treated between July 2021 and December 2022 at UZ Brussel. Treatment included 80 adaptive MRgRT fractions, 10 initial MR plans, and 10 CT-based volumetric-modulated arc therapy (VMAT) plans using an internal target volume (ITV) approach. All patients were treated on the MRIdian system with daily online adaptation and real-time beam gating. Dosimetric endpoints included target coverage, plan quality metrics, and organ-at-risk (OAR) doses. Statistical comparisons were performed using Wilcoxon signed-rank tests.

Results

MRgRT significantly reduced target volumes compared to CT-IGRT (median gross tumor volume (GTV): 40.65 cc vs. 62.56 cc; p = 0.005; median planning target volume (PTV): 64.4 cc vs. 94.4 cc; p = 0.005) and improved dose coverage of both GTV and PTV. Intermediate dose spillage (R50%) was also lower with MRgRT (5.18 vs. 6.56, p = 0.04). MRgRT plans provided superior sparing of critical GI OARs, with median D_5cc relative dose reductions of 42% to the small bowel (p = 0.02), 23% to the duodenum (p = 0.02), and 13% to the stomach (p = 0.01). No significant differences were observed for the liver, kidneys, or large bowel. Treatment was well tolerated, with only grade I–II toxicities reported.

Conclusions

MR-guided adaptive SBRT demonstrated dosimetric superiority over CT-IGRT in pancreatic cancer, with improved target coverage and enhanced GI OAR sparing. These findings support the use of MRgRT to expand the therapeutic window for safe dose escalation. Prospective studies are warranted to confirm clinical benefits.

背景：胰腺癌的立体定向放射治疗（SBRT）由于肿瘤靠近胃肠道（GI）器官而受到限制，增加了毒性的风险。磁共振引导放射治疗（MRgRT）通过优越的软组织可视化、实时肿瘤跟踪和在线自适应规划提供了潜在的优势。本研究旨在定量比较使用在线自适应MRgRT和传统基于计算机断层扫描的图像引导放疗（CT-IGRT）的胰腺癌SBRT的剂量学结果。方法：对2021年7月至2022年12月期间在布鲁塞尔UZ治疗的10例原发性（n = 3）或复发性（n = 7）胰腺腺癌患者的100例计划进行回顾性剂量学分析。治疗包括80个自适应MRgRT分数，10个初始MR计划和10个基于ct的体积调节弧治疗（VMAT）计划，使用内部靶体积（ITV）方法。所有患者均在MRIdian系统上进行每日在线适应和实时光束门控治疗。剂量学终点包括目标覆盖率、计划质量指标和器官风险（OAR）剂量。采用Wilcoxon符号秩检验进行统计学比较。结果：与CT-IGRT相比，MRgRT显著减少了靶体积(中位总肿瘤体积（GTV）： 40.65 cc vs. 62.56 cc；p = 0.005；中位规划目标容积（PTV）： 64.4 cc vs. 94.4 cc；p = 0.005)，提高了GTV和PTV的剂量覆盖率。MRgRT的中剂量溢出（R50%）也较低（5.18 vs. 6.56, p = 0.04）。MRgRT计划提供了对严重胃肠道OARs的优越保留，小肠的中位D5cc相对剂量减少42% (p = 0.02)，十二指肠的中位D5cc相对剂量减少23% (p = 0.02)，胃的中位D5cc相对剂量减少13% （p = 0.01）。在肝脏、肾脏或大肠中未观察到显著差异。治疗耐受性良好，仅报告了I-II级毒性。结论：mr引导下的适应性SBRT在胰腺癌中的剂量学优势优于CT-IGRT，具有改善的靶标覆盖和增强的GI OAR保留。这些发现支持使用MRgRT来扩大安全剂量递增的治疗窗口。有必要进行前瞻性研究以确认临床益处。

{"title":"Online adaptive MR-guided SBRT versus CT-based planning in pancreatic cancer: A single-center dosimetric comparative study","authors":"Randa Kamel, Thierry Gevaert, Dirk Van den Berge, Mark De Ridder","doi":"10.1002/acm2.70391","DOIUrl":"10.1002/acm2.70391","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Stereotactic body radiotherapy (SBRT) for pancreatic cancer is limited by the proximity of tumors to gastrointestinal (GI) organs, increasing the risk of toxicity. Magnetic resonance-guided radiotherapy (MRgRT) offers potential advantages through superior soft tissue visualization, real-time tumor tracking, and online adaptive planning. This study aimed to quantitatively compare dosimetric outcomes of pancreatic cancer SBRT using online adaptive MRgRT versus conventional computed tomography-based image-guided radiotherapy (CT-IGRT).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A retrospective dosimetric analysis was conducted on 100 plans from 10 patients with primary (<i>n</i> = 3) or recurrent (<i>n</i> = 7) pancreatic adenocarcinoma treated between July 2021 and December 2022 at UZ Brussel. Treatment included 80 adaptive MRgRT fractions, 10 initial MR plans, and 10 CT-based volumetric-modulated arc therapy (VMAT) plans using an internal target volume (ITV) approach. All patients were treated on the MRIdian system with daily online adaptation and real-time beam gating. Dosimetric endpoints included target coverage, plan quality metrics, and organ-at-risk (OAR) doses. Statistical comparisons were performed using Wilcoxon signed-rank tests.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>MRgRT significantly reduced target volumes compared to CT-IGRT (median gross tumor volume (GTV): 40.65 cc vs. 62.56 cc; <i>p</i> = 0.005; median planning target volume (PTV): 64.4 cc vs. 94.4 cc; <i>p</i> = 0.005) and improved dose coverage of both GTV and PTV. Intermediate dose spillage (R50%) was also lower with MRgRT (5.18 vs. 6.56, <i>p</i> = 0.04). MRgRT plans provided superior sparing of critical GI OARs, with median D<sub>5cc</sub> relative dose reductions of 42% to the small bowel (<i>p</i> = 0.02), 23% to the duodenum (<i>p</i> = 0.02), and 13% to the stomach (<i>p</i> = 0.01). No significant differences were observed for the liver, kidneys, or large bowel. Treatment was well tolerated, with only grade I–II toxicities reported.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>MR-guided adaptive SBRT demonstrated dosimetric superiority over CT-IGRT in pancreatic cancer, with improved target coverage and enhanced GI OAR sparing. These findings support the use of MRgRT to expand the therapeutic window for safe dose escalation. Prospective studies are warranted to confirm clinical benefits.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 12","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12696390/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145723209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Impact of amalgam dental filling on radiotherapy of head and neck cancer: In vivo dosimetry and dose calculation using AAA and Acuros algorithms 汞合金补牙对头颈癌放疗的影响：使用AAA和Acuros算法进行体内剂量测定和剂量计算。

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics

Pub Date : 2025-12-11 DOI: 10.1002/acm2.70378

Emese Fodor, Zoltán Varga, Gyöngyi Kelemen, Judit Oláh, Anikó Maráz, Katalin Hideghéty

<div> <section> <h3> Introduction</h3> <p>Dental restorations using high-density materials can cause inaccuracies in target and organ-at-risk (OAR) delineation and dose calculations during radiotherapy. These materials, such as amalgam, lead to dose scattering, resulting in enhanced mucositis in adjacent tissues. Minimizing the impact of these artifacts is crucial to improve dose calculation accuracy. This study evaluates the effects of amalgam tooth fillings on dose distribution, compares two dose calculation algorithms (AAA—anisotropic analytical algorithm and AXB—Acuros XB), and assesses their impact on mucosal toxicity during head and neck radiotherapy.</p> </section> <section> <h3> Patients and methods</h3> <p>Forty-nine patients with one to five dental amalgam fillings treated with intensity-modulated radiotherapy (IMRT) for head and neck cancer between 2016 and 2021 at the Oncotherapy Department of Szeged University were included. Planning CTs with and without metal artifact reduction (MAR) were used to delineate targets and OARs. Treatment plans were optimized using the Eclipse Treatment Planning System with the AAA and AXB algorithms. In vivo dosimetry was performed using Gafchromic EBT3 films embedded in thin Styrofoam slabs during one of the first five treatment sessions. Statistical analyses, including <i>t</i>-tests, ANOVA, paired <i>t</i>-tests, and Kaplan–Meier curves, were conducted to evaluate the influence of clinical and dosimetric factors on dose perturbations and mucositis onset.</p> </section> <section> <h3> Results</h3> <p>Metal artifact reduction (MAR) correction improved contouring accuracy. Dose values calculated with AAA were higher than those with AXB for both mean and maximum dose to OARs and mucosa (Dmean: AAA > 10.57%, Dmax: AAA > 6.8% compared to AXB). Measured doses showed better agreement with AAA-calculated Dmean values (<i>p</i> = 0.341) but were significantly underestimated by AXB (<i>p</i> < 0.001). There was no difference in dose perturbation according to tumor localization, gross tumor volume, planning target volume, or the use of a tongue wedge. The number of amalgam-filled teeth correlated significantly with the earlier onset of mucositis, with each additional filling advancing mucositis appearance by 1.7 days.</p> </section> <section> <h3> Conclusion</h3> <p>High-density dental materials cause significant dose perturbations in the oral cavity during head and neck radiotherapy. In our clinical IMRT setup, the AAA algorithm demonstrated closer agreement with in vivo film measurements compared to AXB

使用高密度材料的牙科修复可能导致放射治疗过程中靶器官和危险器官（OAR）划定和剂量计算的不准确。这些物质，如汞合金，会导致剂量散射，导致邻近组织的粘膜炎加重。尽量减少这些伪影的影响是提高剂量计算精度的关键。本研究评估了汞合金补牙对剂量分布的影响，比较了两种剂量计算算法（aaa -各向异性分析算法和AXB-Acuros XB算法），并评估了它们对头颈部放疗期间粘膜毒性的影响。患者和方法：纳入塞格德大学肿瘤治疗科2016年至2021年间49例接受1至5种牙科汞合金填充物调强放疗（IMRT）治疗头颈癌的患者。有或没有金属伪影还原（MAR）的计划ct用于描绘目标和桨。采用Eclipse治疗计划系统，采用AAA和AXB算法对治疗方案进行优化。在前5个疗程中的一个疗程中，使用Gafchromic EBT3薄膜嵌入薄聚苯乙烯泡沫板进行体内剂量测定。统计分析包括t检验、方差分析、配对t检验和Kaplan-Meier曲线，以评估临床和剂量学因素对剂量扰动和粘膜炎发病的影响。结果：金属伪影减少（MAR）校正提高了轮廓精度。与AXB相比，AAA计算的桨叶和粘膜的平均和最大剂量值均高于AXB （Dmean: AAA > 10.57%, Dmax: AAA > 6.8%）。测量剂量与aaa计算的Dmean值吻合较好（p = 0.341），但AXB明显低估了测量剂量(p)。结论：高密度牙体材料在头颈部放疗过程中引起明显的口腔剂量摄动。在我们的临床IMRT设置中，尽管理论和文献报道了AXB在异质条件下的优势，但与AXB相比，AAA算法与体内膜测量更接近一致。这种差异强调了算法的性能取决于临床技术、剂量学方法和剂量报告模式。此外，每次补牙都与早期黏膜炎发病有关。

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引用次数: 0

Detection of the Linac Jaw face angle misalignment using high energy electron beam symmetry 利用高能电子束对称检测直线颚面角错位。

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics

Pub Date : 2025-12-10 DOI: 10.1002/acm2.70419

Song Gao, Andres Cibrian, Jared Ohrt, Peter Balter

Purpose

To demonstrate the usage of a high energy electron beam symmetry measured at different collimator angles to detect jaws face angle misalignments on Varian TrueBeam linear accelerators (linac) during acceptance and commissioning processes.

Methods

During the linac acceptance, all beams were steered to a symmetric shape with the gantry and collimator at 0°. We noted that the symmetries of higher energies electrons (e.g., 16 MeV, 20 MeV) changed over 2% when measured with the collimator at 90° and/or 270° for two linacs commissioned within 5-months of each other. Misaligned applicators were ruled out as the cause of this issue. Eventually, this was traced to the X-jaw face angle not matching beam divergence. After the problem was identified and the jaws were realigned by manufacture's engineers and all beams were re-steered to a symmetric shape at collimator 0° and verified at collimator 90° and 270°.

Results

Prior to the manufacturer adjusting the jaw face angles, the maximum observed electron beam symmetry changes with 90° collimator rotation were 2.0% and 2.6% for linac 1 and linac 2, respectively. After realigning, the jaw face angles the maximum observed electron beam symmetry changes with 90° collimator rotation were within 1.0% for all beams on both linacs.

Conclusion

We have demonstrated that changes in symmetry of high energy electron beam with 90° collimator rotation can signal that the jaw face angle is not properly aligned with beam divergence.

目的：演示在瓦里安TrueBeam直线加速器（直线加速器）的验收和调试过程中，以不同准直器角度测量高能电子束对称性来检测颚面角度偏差的使用。方法：在直线验收过程中，所有光束都被引导到一个对称的形状，龙门和准直器在0°。我们注意到高能电子（例如，16 MeV, 20 MeV）的对称性变化超过2%，当使用准直器在90°和/或270°测量时，两台直线加速器彼此在5个月内使用。未对准的涂抹器被排除为导致此问题的原因。最终，这被追溯到x颌面角与光束发散不匹配。在确定问题后，制造商的工程师重新调整了钳口，并在准直器0°处将所有光束重新导向对称形状，并在准直器90°和270°处进行了验证。结果：在制造商调整颚面角度之前，直线1和直线2在90°准直器旋转时观察到的最大电子束对称性变化分别为2.0%和2.6%。重新调整后，两种直线上所有光束在准直器旋转90°时所观察到的最大电子束对称性变化都在1.0%以内。结论：当准直器旋转90°时，高能电子束的对称性发生变化，表明电子束的颚面角与束流散度没有正确对准。

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引用次数: 0

Combined application of block and modulation factors to reduce the volume of the low dose area in helical tomotherapy plans for lung cancer 阻断因子与调节因子联合应用减少肺癌螺旋断层治疗低剂量区体积。

IF 2.2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics

Pub Date : 2025-12-10 DOI: 10.1002/acm2.70372

Sijin Zhu, Tianwen Zhang, Yutao Zhao, Jinli Peng, Jingyan Gao, Yunyan Yang, Yan Xu, Jiawen Yan, Ya Li

Background

The helical tomotherapy (HT) system can expose more normal lung tissue to low radiation doses, resulting in extensive low-dose distribution in both lungs which may induce radiation pneumonitis (RP).

Purpose

This study aims to optimize dosimetric parameters and identify a clinically feasible treatment plan by analyzing the impact of different block settings and modulation factor (MF) combinations on HT plans for lung cancer to reduce the low-dose exposure volumes in normal lung tissue.

Methods

We retrospectively reviewed 14 lung cancer patients who received radiotherapy. These cases were optimized using different modulation factors (MFs: 3, 4, 5) and block techniques (Unblocked, Directional, Complete). The impact of MF and block combinations on reducing low-dose bath (e.g., V5, V10) in lung tissue was evaluated by analyzing dose distribution maps, dose–volume histograms (DVH), homogeneity index (HI), conformity index (CI), and treatment time for each optimized HT plan combination.

Results

Block settings and higher MF exerted minimal influence on the average dose to the target volume. With stricter block constraints and higher MF, HI increased (range: 17.39%–27.54%) and CI decreased (range: 2.76%–17.43%); although both indices showed slight deterioration, they remained within acceptable clinical limits. Treatment time increased substantially (range: 15.77%–131.58%). The block technique significantly reduced V5 in the bilateral lungs and the contralateral (healthy) lung, with less impact on the ipsilateral (affected) lung. The combination of block and high MF effectively reduced V5.

Conclusions

To balance target volume coverage (high dose), dose distribution uniformity, and treatment duration while reducing low-dose irradiation to normal lung tissue, we recommend implementing Directional block with an MF range of 3–4 to optimize the HT plan for patients with unilateral lung cancer.

背景：螺旋断层治疗（HT）系统可以使更多的正常肺组织暴露于低剂量辐射下，导致双肺广泛的低剂量分布，可能诱发放射性肺炎（RP）。目的：本研究旨在通过分析不同阻滞设置和调节因子（MF）组合对肺癌HT治疗方案的影响，优化剂量学参数，确定临床可行的治疗方案，以减少正常肺组织中的低剂量暴露量。方法：回顾性分析14例接受放射治疗的肺癌患者。这些案例使用不同的调制因子（MFs: 3,4,5）和块技术（Unblocked, Directional, Complete）进行优化。通过分析各优化方案组合的剂量分布图、剂量-体积直方图（DVH）、均匀性指数（HI）、一致性指数（CI）和治疗时间，评估MF和block组合对减少肺组织低剂量浴（如V5、V10）的影响。结果：阻滞设置和较高的MF对靶体积的平均剂量影响最小。区块约束越严格，MF越高，HI值越高（范围：17.39% ~ 27.54%），CI值越低（范围：2.76% ~ 17.43%）；虽然两项指标均有轻微恶化，但仍在可接受的临床范围内。治疗时间明显增加（幅度：15.77% ~ 131.58%）。阻滞技术可显著降低双侧肺和对侧（健康）肺的V5，对同侧（患病）肺的影响较小。阻断与高MF的结合有效降低了V5。结论：为了平衡靶体积覆盖（高剂量）、剂量分布均匀性和治疗时间，同时减少对正常肺组织的低剂量照射，我们建议对单侧肺癌患者实施定向阻断，其MF范围为3-4，以优化HT计划。

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