Medical physics最新文献

{"title":"MRI-based radiomics model for predicting VEGFA expression and prognosis in lower-grade glioma","authors":"Kun Zhao, Xinyu Hong, Hongrong Cheng, Shoucheng Xu, Dongliang Zhao, Jianyang Lin, Yongbing Gu, Guoqiang Ren, Baomin Chen, Liping Zhan, Yuanwei Wang","doi":"10.1002/mp.70615","DOIUrl":"10.1002/mp.70615","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Gliomas are the most common primary tumors of the central nervous system. Their treatment remains highly challenging, with high rates of associated disability and mortality. Conventional prognostic indicators no longer adequately satisfy the clinical demands of precision medicine. Therefore, it is essential to further explore novel prognostic biomarkers to enable accurate risk stratification and to provide new reference indicators for personalized precision therapy.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purposes</h3>\u0000 \u0000 <p>This study aimed to investigate the prognostic significance of vascular endothelial growth factor A (VEGFA) in patients diag nosed with lower-grade gliomas (LGGs) using an MRI based radiomics model.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Data regarding VEGFA expression and clinical records of LGG patients were retrieved from The Cancer Genome Atlas (TCGA). Corresponding preoperative MRI data were obtained from The Cancer Imaging Archive (TCIA) for radiomic feature extraction. Patients were stratified into high- and low- VEGFA expression groups based on survival information from the current cohort using the survminer package. The overall survival (OS) was assessed using Kaplan–Meier analysis and Cox proportional hazards regression. Predictive models were developed using logistic regression (LR), and model performance was evaluated via receiver operating characteristic (ROC) curve analysis, with area under the curve (AUC) values reported. An optimized model incorporating the Akaike information criterion (AIC) was also constructed (AIC-LR).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>VEGFA expression was significantly associated with OS (<i>P</i> = 0.002). Multivariate Cox regression confirmed VEGFA as an independent prognostic factor (hazard ratio [HR] = 2.545, 95% confidence interval: 1.422–4.555). Furthermore, VEGFA expression correlated with immune infiltration levels, particularly of M1 and M2 macrophages and T follicular helper cells, and was associated with enrichment in Wnt signaling and B cell receptor signaling pathways. The LR and AIC-LR models demonstrated acceptable predictive performance, with AUCs of 0.728 (95% CI: 0.612–0.843) and 0.725(95% CI: 0.612–0.839) in the training cohort, and 0.704 (95% CI: 0.562–0.847) and 0.718(95% CI: 0.576–0.861) in the validation cohort, respectively.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The MRI based radiomics model showed potential fo","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13535709/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148876851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Size-specific weighted detectability index for computed tomography image characterization","authors":"Isabelle Fitton, Joël Greffier, Djamel Dabli, Claire Van Ngoc Ty","doi":"10.1002/mp.70668","DOIUrl":"10.1002/mp.70668","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Technological developments in computed tomography (CT) have increased the diversity of acquisition and reconstruction strategies available for clinical imaging. Task-based image quality metrics that account for patient-size variability are needed to characterize reconstructed image performance and support protocol optimization across clinically relevant imaging conditions.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To propose and evaluate a novel size-specific weighted detectability index (SSW-d’), a task-based image performance metric (d') that incorporates lesion contrast weighting and water-equivalent diameter variability for the characterization of CT images acquired at low dose.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>First, a multi-sized image quality phantom was scanned on two CT systems: one photon-counting CT (PCCT, CT1) and one CT equipped with energy integrating detectors (EICT, CT2). Acquisitions were performed with a volume CT dose index (CTDI<sub>vol</sub>) of 3.2 mGy at 120kV without a tin filter (Sn), at Sn100 and Sn140kV. Second, acquisitions at 3.2 mGy were performed on CT1 using three reconstruction algorithms (FBP, QIR-2, QIR-4). Subsequently, five reconstruction kernels (Br32, Br44, Br56, Br68, and Br76) were evaluated at 1.1 mGy. A higher CTDI<sub>vol</sub> value of 6 mGy, combined with Br68 and QIR-4, was also tested. The detectability index values (d’) were determined for two 10 mm diameter lesions according to two different levels of contrast, based on iodine and bone equivalent tissue. The SSW-d’ was calculated for each CT system and for each individual task. Then, SSW-d’ was expanded to include both tasks, applying contrast weights determined for each of them.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>On CT1, the highest SSW-d’ values were 19.3 ± 0.3 and 6.9 ± 0.0, at 120 kV for bone and iodine rods, respectively. On CT2, the highest SSW-d’ results were 19.0 ± 0.3 and 4.9 ± 0.0 at Sn100 kV for bone and iodine rods, respectively. The lowest values were at Sn140kV for both rods and CT systems. When encompassing both tasks, the maximum SSW-d’ values were 10.05 ± 0.04 and 8.25 ± 0.03, respectively obtained at 120 kV for CT1 and at Sn100 kV for CT2. The results showed that the lowest SSW-d’ values were at Sn140 kV for both CT systems. Comparison of acquisition and reconstruction parameters showed that the highest SSW-d′ value was obtained using the Br32 kernel (17.6 ± 0.7), approximately twofold higher than that obtained at 6 mGy (8.6 ± 0.3). The lowest SSW-d′ value (1.9 ± 0","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13535753/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148876923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine Model-Specific Delivery Sequence Optimization for Spot-scanning Proton Arc Therapy Using a Compact Superconducting Synchrocyclotron","authors":"Peilin Liu,&nbsp;Lewei Zhao,&nbsp;Xiaoda Cong,&nbsp;Gang Liu,&nbsp;Xiaoqiang Li,&nbsp;Xuanfeng Ding","doi":"10.1002/mp.70658","DOIUrl":"10.1002/mp.70658","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Spot scanning proton arc therapy (SPArc) combines the dosimetric advantages of proton therapy with the beam-angle freedom of arc delivery. However, current planning algorithms rely on static delivery assumptions that do not account for the temporal characteristics of pulsed-beam synchrocyclotron systems during continuous gantry rotation. This mismatch between nominal plans and actual treatment delivery may lead to clinically meaningful dose deviations.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To develop and evaluate a dynamic arc delivery sequencing optimization framework that incorporates machine-specific delivery characteristics to minimize deviations between planned and delivered dose in SPArc.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A five-step dynamic arc delivery sequencing optimization framework was developed. The framework includes: (1) static and dynamic delivery time calculation, (2) spot and energy-layer disassembling, (3) incorporation of dynamic delivery timing into control points, (4) spot-weight fine-tuning, and (5) reconstruction of energy-layer sequences. Five multi-metastatic brain stereotactic radiosurgery cases were retrospectively evaluated. Delivery accuracy, efficiency and plan quality were assessed using virtual machine logfiles.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The sequencing optimization framework substantially improved delivery accuracy while preserving plan quality and efficiency. For the total gross tumor volume, the mean absolute D98 deviation between planned and virtual logfile reconstructed doses decreased from 77.4 ± 81.0 cGyE (4.2 ± 4.5%) with static SPArc plans to 9.6 ± 4.0 cGyE (0.5 ± 0.2%) after sequencing optimization. For the worst metastasis in each case, D98 deviation decreased from 184.4 ± 145.2 cGyE (9.8 ± 7.9%) to 19.0 ± 16.4 cGyE (1.0 ± 0.8%), and D2 deviation decreased from 148.4 ± 114.4 cGyE (6.8 ± 5.6%) to 13.2 ± 8.6 cGyE (0.6 ± 0.4%). Target coverage and normal brain sparing remained statistically unchanged (p &gt; 0.05), and total delivery times differed by &lt; 1 s.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The proposed sequencing optimization framework addresses the temporal mismatch between static SPArc planning and dynamic delivery in synchrocyclotron-based systems. By improving delivery accuracy without compromising plan quality or delivery efficiency, the framework demonstrates the feasibility of incorporating machine-specific delivery timing into dynamic proton arc therapy.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148868777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-modal direct LINAC parameter prediction for pancreatic VMAT: An optimization-free approach","authors":"Zixu Guan,&nbsp;Yukine Shimizu,&nbsp;Takahiro Iwai,&nbsp;Michio Yoshimura,&nbsp;Takashi Mizowaki,&nbsp;Mitsuhiro Nakamura","doi":"10.1002/mp.70656","DOIUrl":"10.1002/mp.70656","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Pancreatic cancer Volumetric Modulated Arc Therapy (VMAT) planning presents a significant dosimetric challenge due to the high-dose gradients required to spare adjacent, radiosensitive organs at risk (OARs) like the stomach and duodenum. This anatomical complexity has limited the scope of automated planning for this site. Broadly, while deep learning (DL) has been introduced to streamline treatment planning, most existing models only predict intermediate outputs, such as dose distributions or fluence maps, which still necessitate a subsequent, computationally expensive inverse optimization step on a treatment planning system.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;To address these challenges, we aim to develop an optimization-free fully automated VMAT planning framework for pancreatic cancer. As a key component of this system, this study introduces a DL model designed to directly generate machine parameters from dose distributions and anatomical contours.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;A total of 200 vmat plans for pancreatic cancer (prescription: 42 Gy in 15 fractions) were retrospectively collected. The dataset was randomly split into training (&lt;i&gt;n &lt;/i&gt;= 170), validation (&lt;i&gt;n&lt;/i&gt; = 10), and testing (&lt;i&gt;n&lt;/i&gt; = 20) sets. The proposed Multi-modal, Attention &amp; Transformer-Enhanced U-Net (MATE-UNet) utilizes beam's-eye-view (BEV) projections of the reference dose distribution and anatomical contours to directly predict machine-executable multi-leaf collimator (MLC) apertures and Monitor Units (MUs). The proposed model was benchmarked against baseline U-Nets (using contour-only, dose-only, and combined inputs) on the testing set. Model accuracy was assessed using the Dice Similarity Coefficient (DSC) for MLC and Mean Absolute Error (MAE) for MU, while plan quality was evaluated using clinical dose-volume histogram (DVH) metrics and Conformity Index (CI), Homogeneity Index (HI), and Gradient Index (GI).&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;MATE-UNet achieved a clinical acceptance rate of 100% (20/20), compared to 70% for the best-performing baseline model. In terms of prediction accuracy, the proposed model achieved a DSC of 0.9553 ± 0.0042 for MLC apertures and an MAE of 1.960 ± 0.396 for MU. Dosimetric evaluation demonstrated that, relative to the reference plans, MATE-UNet maintained comparable target coverage, CI (0.773), and HI (0.100), while achieving a significantly improved GI (3.732, &lt;i&gt;p&lt;/i&gt; &lt; 0.05). Furthermore, MATE-UNet significantly reduced the V&lt;sub&gt;39Gy&lt;/sub","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13527261/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148868282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stand-alone graph-based lung airway labeling with quantitative validations","authors":"Hairong Chen,&nbsp;Arezoo Modiri,&nbsp;Amit Sawant","doi":"10.1002/mp.70634","DOIUrl":"10.1002/mp.70634","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Previous studies have shown that protecting airways connected to high-functioning lung parenchyma reduces the risk of post-treatment radiation-induced lung injury. To account for airway sparing in radiotherapy planning, a critical requirement is to characterize the geometry and radiation response of individual airway segments.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To report on automated individual airway labeling framework with branch dimensions extracted from CT-derived virtual bronchoscopy images.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We developed an automated graph-based topological labeling algorithm with bifurcation detections and context-based denoising. In-house modules for estimating airway diameters and tube length were also developed. Both labeling and meta-information estimation were validated against a commercial virtual bronchoscopy software in data from 20 lung cancer patients. Labeling metrics were segmentation surface scores: i.e., average symmetric surface distance (ASSD), normalized surface distance (NSD), and 95th percentile surface Hausdorff (HD95surf). Meta-information metrics were absolute errors of branch major diameter, minor diameter, and tube length. Mean absolute error (MAE) and root mean square error (RMSE) were calculated to assess meta-information deviations in both validations.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Mean and standard deviations were 0.56 ± 0.21 mm for ASSD, 87.66 ± 3.20% for NSD, and 2.51 ± 0.68 mm for HD95surf. Deviations of meta-information metrics in labeling validation were MAE/RMSE: 0.33 ± 0.09/0.67 ± 0.16 mm for major diameter, 0.24 ± 0.07/0.53 ± 0.15 mm for minor diameter, and 3.27 ± 0.82/5.53 ± 1.53 mm for tube length. Deviations of meta-information metrics in meta-information validation were MAE/RMSE: 1.81 ± 0.30/2.31 ± 0.41 mm for major diameter, 1.25 ± 0.27/1.14 ± 0.26 mm for minor diameter, and 2.20 ± 0.32/3.24 ± 0.49 mm for tube length.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The proposed open-source framework provides stand-alone, fully-automated airway labeling with very good agreement with a commercial virtual bronchoscopy system. Our method shows strong potential for use in functionally-guided lung sparing in radiation treatment plan optimization.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.70634","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148835124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inverse-consistent deformable image registration to propagate biomechanical constraints for online adaptive radiotherapy","authors":"T. J. W. Draper,&nbsp;C. Zachiu,&nbsp;B. W. Raaymakers","doi":"10.1002/mp.70645","DOIUrl":"10.1002/mp.70645","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Accurate motion estimation remains a key challenge in adaptive radiotherapy (ART). Voxel-wise accuracy is required, as registration errors can compromise the treatment quality. Locally constrained image registration is a promising technique to further improve ART treatment, but relies heavily on quick and accurate delineations of the local areas used to constrain. In online clinical scenarios, these delineations are often available on pre-treatment image volumes, but not on the online data due to accuracy and time constraints.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;We developed a deformable image registration (DIR) framework that integrates inverse consistency with local biomechanical constraints, enabling tissue-specific motion modeling using contours from only a single image volume. This approach enforces tissue-specific constraints on the inverse deformation field and propagates them to the forward deformation through inverse consistency optimization, yielding anatomically plausible motion estimates for ART workflows.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The proposed framework was evaluated in three scenarios relevant to ART: abdominal CT-CT and multi-modality CT-MR registration with incompressibility constraints on the liver and kidneys, as well as thoracic CT-CT registration with local rigidity constraints on the ribs and vertebrae. We also investigated the robustness of the framework to image degradation by evaluating motion estimates under added Gaussian noise and artificially induced streaking artifacts. Performance was compared to a baseline DIR model and an unconstrained inverse-consistent model. Accuracy and anatomical consistency were assessed using landmark alignment, contour overlap, and physics-based motion analysis.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;We demonstrate that local biomechanical constraints imposed on the inverse deformation field are successfully propagated to the forward motion field through inverse consistency optimization. The proposed framework improves the biomechanical plausibility of the resulting deformation fields at a small cost of landmark-based accuracy, and maintaining comparable results in terms of contour-based evaluation. The method is applicable to both mono- and multimodality registration and is more robust to noise and artifacts that appear from image acquisition and reconstruction.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusions&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.70645","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148835064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental activation assessment of open-type yoke in a PET cyclotron by non-destructive/destructive γ-ray measurement approaches","authors":"Go Yoshida,&nbsp;Hiroshi Matsumura,&nbsp;Akihiro Toyoda,&nbsp;Hajime Nakamura,&nbsp;Kazuyoshi Masumoto,&nbsp;Taichi Miura,&nbsp;Eisuke Watanabe,&nbsp;Kiyokazu Tsugane,&nbsp;Katsuhiko Saito,&nbsp;Iwane Koumura,&nbsp;Hiroyuki Uno,&nbsp;Masahiko Kozaki,&nbsp;Ayumi Yamamoto,&nbsp;Jun Toyohara,&nbsp;Kei Wagatsuma","doi":"10.1002/mp.70649","DOIUrl":"10.1002/mp.70649","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;During decommissioning of positron emission tomography (PET) cyclotron facilities, metallic components—including the iron yoke—are typically classified as radioactive waste, incurring substantial disposal costs. In contrast to concrete, standardized decommissioning procedures for metallic components have not yet been established.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;This study aimed to experimentally assess activation in a PET cyclotron and provide fundamental data for establishing decommissioning guidelines for metallic components. The investigation focused on residual activity in the yoke and center pole, which are among the heaviest structural parts.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;A PET cyclotron that operated for 23 years at the Tokyo Metropolitan Institute for Geriatrics and Gerontology was examined 6 years after the cyclotron's complete shutdown using two complementary approaches: non-destructive γ-ray measurements and destructive core-boring analysis.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;&lt;sup&gt;60&lt;/sup&gt;Co was the predominant residual radionuclide. On the outer surfaces, &lt;sup&gt;60&lt;/sup&gt;Co specific activity typically ranged from 0.02 to 0.10 Bq/g, with many locations below the 0.1 Bq/g clearance level. Cross-sectional mapping showed exponential attenuation behavior from the interior outward. Higher activation in the center pole (up to ∼1.0 Bq/g) was observed. &lt;sup&gt;54&lt;/sup&gt;Mn was one to two orders of magnitude lower than &lt;sup&gt;60&lt;/sup&gt;Co at 6 years post-shutdown. Non-destructive and destructive results were in close agreement, validating the quantitative use of γ-detectors for near-surface activity. A hypothetical time-dependent decay estimation, based on the non-destructive/destructive findings, was performed to project a required cooling period to meet clearance.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusions&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Activation levels in PET cyclotron components can be effectively assessed using combined non-destructive and destructive approaches. The complex distribution of residual activity was observed in the yoke and center poles. Decay projections indicated that approximately half of the yoke would fall below the clearance level within 15 years and nearly all components within 23 years after shutdown. These findings provide essential benchmarks for improving simulation-based activation modeling and can be broadly applied to similar PET cyclotron systems.&lt;/p&gt;\u0000 &lt;/","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13504305/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148815335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modified Z-resolution protocol for digital breast tomosynthesis","authors":"Priyash Singh,&nbsp;Nyasha G. Maforo,&nbsp;Bruno Barufaldi,&nbsp;Andrew D. A. Maidment,&nbsp;Raymond J. Acciavatti","doi":"10.1002/mp.70625","DOIUrl":"10.1002/mp.70625","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The EUREF protocol measures the z-resolution of a digital breast tomosynthesis (DBT) system via a ball bearing's (BB) point-spread function (PSF) and is quantified as the full-width at half-maximum (FWHM) of the associated artifact spread function (ASF). PSF is largely governed by the apparent angle (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mi&gt;α&lt;/mi&gt;\u0000 &lt;annotation&gt;$alpha $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;), defined as the radian angle subtended by the BB across the X-ray sources, which in turn depends on the BB's location and acquisition geometry. Under fixed DBT geometry and reconstruction conditions, the FWHM is therefore expected to follow a predictable spatial trend. However, we found that the EUREF protocol does not consistently reproduce this behavior; it fails to capture the gradual rise in FWHM for anteriorly displaced BBs expected from a narrowing &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mi&gt;α&lt;/mi&gt;\u0000 &lt;annotation&gt;$alpha $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; (with which FWHM is inversely correlated) and exhibits a systematic bias to the stochastic noise in the reconstruction image.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The purpose of this work was to develop a z-resolution metric that more rigorously reflects the underlying local PSF's &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mi&gt;α&lt;/mi&gt;\u0000 &lt;annotation&gt;$alpha $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; without incurring a sensitivity to stochastic noise. We propose a protocol that uses multiplanar reconstruction to track the oblique BB signal in its natural spatial scale, uses means instead of maxima to generate the ASF, and employs a functional fit to estimate the FWHM more robustly—hereafter referred to as the Modified Protocol.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The protocol was evaluated using analytically simulated and experimentally acquired DBT reconstructions of BBs displaced anteriorly and superiorly and compared against the EUREF protocol. The percent change in FWHM due to stochastic noise was used to quantify systematic noise susceptibility. The strength of the anti-correlation between FWHM and apparent angle α was used to assess each protocol's agreement with the PSF geometry.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;By demonstrating a consistent linear anti-correlation between FWHM and α for both","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13504301/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148815383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-fidelity Monte Carlo fusion for BNCT dose calculation using a dual-branch network","authors":"Leiming Li,&nbsp;Xin Hong,&nbsp;Yongquan Wang,&nbsp;Gan Huang,&nbsp;Zhiqiang Wu,&nbsp;Yingjie Xiao,&nbsp;Hiroki Tanaka,&nbsp;Hiroshi Watabe","doi":"10.1002/mp.70646","DOIUrl":"10.1002/mp.70646","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Boron neutron capture therapy (BNCT) is a binary radiotherapy that selectively kills tumor cells. Its clinical implementation relies on Monte Carlo (MC)-based treatment planning systems, which are time-consuming and limit clinical workflow efficiency.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To address this limitation, we propose a Multi-Fidelity MC-based Dual-Branch Network (MFMC-DBN) that leverages complementary information from low- and high-fidelity MC simulations through dual-branch feature fusion, enabling accurate and efficient BNCT dose calculation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The model was trained, validated, and tested using clinical data from 112 glioblastoma patients. Low-statistics coarse and fine mesh MC dose distributions (6.5×10⁶ particle histories) and patient CT information were used to predict three-dimensional dose distributions. Performance was compared with an MC denoising method and a conventional neural network (NN) approach.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>MFMC-DBN outperformed both the NN and MC denoising methods across evaluated metrics. It achieved a mean absolute percentage error (MAPE) of 1.98% in the gross tumor volume (GTV). Organ-specific MAPEs ranged from 1.1% to 3.9%, with a maximum mean absolute error (MAE) of0.28 Gy (RBE). Gamma analysis further showed high spatial agreement, with passing rates of 99.8% within the patient contour and 99.3% in the GTV under the 3%/3 mm criterion. The proposed method maintained high dosimetric accuracy while substantially accelerating BNCT dose calculation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>MFMC-DBN effectively integrates multi-fidelity MC information through a dual-branch attention mechanism, enabling rapid and accurate 3D BNCT dose prediction. By significantly reducing computation time compared with full MC simulations while preserving dosimetric fidelity, these results support the feasibility of the proposed framework for accelerated BNCT dose calculation under a fixed beam configuration.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13501215/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148809187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance evaluation of a dedicated brain PET scanner with octagonal detector arrangement using a modified NEMA NU2 2018 protocol","authors":"Ekaterina Mikhaylova,&nbsp;Max L. Ahnen,&nbsp;Henryk Barthel,&nbsp;Jan Debus,&nbsp;Jannis Fischer,&nbsp;Martin Huellner,&nbsp;Markus Jehl,&nbsp;Philipp A. Kaufmann,&nbsp;Michael Rullmann,&nbsp;Bernhard Sattler,&nbsp;Karen G. Steinhoff,&nbsp;Juan Streb,&nbsp;Solveig Tiepolt,&nbsp;Valerie Treyer,&nbsp;Osama Sabri,&nbsp;Ilaria Sacco","doi":"10.1002/mp.70578","DOIUrl":"10.1002/mp.70578","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;This work presents the NEMA NU2 2018 performance evaluation of the NeuroLF Basic, a compact and fully integrated brain positron emission tomography (PET) system based on 10-mm-long LYSO crystals.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The goal is to assess its quantitative performance and imaging capabilities for neuroimaging applications.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The evaluation includes measurements and simulations of spatial resolution, scatter fraction, noise equivalent count rate (NECR), accuracy of corrections, image quality, and sensitivity, following standardized protocols to ensure reliable and reproducible results. In addition, imaging of the Hoffman 3-dimensional brain phantom was performed to visually evaluate system performance. Image quality was assessed using an ACR Esser phantom, which fits within the compact bore of the NeuroLF scanner.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The average filtered-back-projection spatial resolution, measured at 1 and 10 cm radial offsets, was 2.51 and 3.61 mm, respectively, highlighting the system's ability to capture details essential for neuroimaging. The scatter fraction was 24.2% at the peak NECR, reflecting the system's capability to minimize scattered events. The peak NECR was 55.3 kcps at an activity concentration of 8.1 kBq/mL, demonstrating the system's efficiency in handling typical neuroimaging count rates. NeuroLF showed excellent accuracy of corrections at 3.7% and good image contrast for hot vials in a warm background in the adapted image quality procedure with the ACR Esser phantom, achieving values of 87.5%, 77%, 60%, and 35.8% for 25-, 16-, 12-, and 8-mm-diameter vials, respectively, with a maximum background variability of 10% for the 8-mm vial. Sensitivity, evaluated using a 70-cm line source, was 5.85 cps/kBq at the center of the field of view and 8.08 cps/kBq at a 10 cm radial offset. Images of the Hoffman phantom further demonstrated the system's ability to produce realistic brain uptake distributions. The measured NEMA NU2 2018 results showed good agreement with Monte Carlo simulation results, validating the simulated NeuroLF model for future research and optimization.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusions&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;These results demonstrate the NeuroLF's potential to deliver high-quality images, good detection efficiency, and robust quantitative performance. The comprehensive NEMA NU2 2018 evaluation, supported by Hoffman phantom imaging, confirms NeuroLF's capability as a valuable tool for clinical appli","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148809362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}