Medical physics最新文献

{"title":"A simulation study of a novel spiral volumetric modulated arc therapy for enhanced dose delivery efficiency and quality in radiotherapy","authors":"Kuo Li, Wei Zhang, Xingmin Ma, Qichao Zhou, Jian Zhu","doi":"10.1002/mp.70423","DOIUrl":"10.1002/mp.70423","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Conventional volumetric modulated arc therapy (VMAT) is limited by its longitudinal field size for large targets, often requiring multiple isocenters, while Helical Tomotherapy (HT) offers superior longitudinal conformity but suffers from prolonged treatment times due to its narrow fan beam.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This simulation study proposes a novel spiral volumetric modulated arc therapy (SVMAT) technique designed to bridge this gap by synergizing continuous couch movement with dynamic MLC modulation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The SVMAT technique was implemented on a model of ring-gantry linac with dual-layer staggered MLC. Its core is a direct aperture optimization algorithm that discretizes the delivery path into finite projections, concurrently optimizing MLC aperture, monitor unit weight, gantry angle, and couch position. A comprehensive dosimetric and efficiency comparison was conducted against state-of-the-art VMAT and HT plans for three clinically challenging scenarios: hippocampal-sparing whole-brain radiotherapy (HS-WBRT), bilateral breast radiotherapy (BBRT), and craniospinal irradiation (CSI), including a pediatric subgroup.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>SVMAT demonstrated comparable or superior target coverage and conformity index to VMAT and HT across all cases. Its most significant advantage was in organ-at-risk (OAR) sparing. For HS-WBRT, SVMAT significantly reduced the maximum (D<sub>max</sub>) and mean (D<sub>mean</sub>) doses to the hippocampus compared to both VMAT and HT (<i>p</i> < 0.05). For BBRT, SVMAT notably reduced the heart D<sub>mean</sub> (4.78 ± 0.86 Gy vs. 9.47 ± 3.44 Gy) for VMAT. In CSI, SVMAT reduced the lens D<sub>max</sub> by over 33% and the heart D<sub>mean</sub> by 36.1%. Also, the pediatric CSI analysis confirmed these benefits, with SVMAT significantly reducing doses to developing organs. Regarding efficiency, SVMAT's beam on time was significantly shorter than HT's across all plans (reductions of 33.1% to 55.3%) and was comparable to the multi-isocenter VMAT in CSI.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The SVMAT technique successfully integrates the dynamic delivery of VMAT with the longitudinal integration and single-isocenter capability of HT. By offering enhanced OAR sparing and reduced treatment times, SVMAT represents a significant advancement in radiotherapy, showing immense potential","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13049104/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147617212","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":"Comparative evaluation of dual-layer spectral CT protocols for mouse chest imaging","authors":"Shupei Zhong,&nbsp;Chen Gao,&nbsp;Qunhao Huang,&nbsp;Ting Wu,&nbsp;Fan Zhang,&nbsp;Hao Zheng,&nbsp;Shushan Dong,&nbsp;Qi Yin,&nbsp;Xinjing Lou,&nbsp;Linyu Wu,&nbsp;Maosheng Xu","doi":"10.1002/mp.70409","DOIUrl":"10.1002/mp.70409","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Imaging studies using mouse models provide key technical support for dynamic monitoring of lung diseases, and spectral CT provides high-precision tissue contrast and compositional analysis; however, a parameter framework for mouse lung imaging has yet to be established.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study investigates the effect of the filtering, slice thickness, and spectral parameters on the quality of chest scan images.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Thirty C57BL/6 mice were selected and allowed to acclimate to conditions inside the animal facility. After conducting Philips spectral CT chest scans on mice weighing 20, 25, and 30 g, six filters and two slice thickness settings were employed for multi-dimensional reconstruction. Using the repeated regions of interest (ROI) measurement method, we systematically evaluated both quantitative and qualitative image quality. Quantitative indicators included CT value, noise level, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Qualitative scores were assigned to four types of images: virtual monoenergetic images (VMI), virtual unenhanced images (VNC), and effective atomic number maps (z-effective). The Kruskal–Wallis test was used to assess quantitative metrics, whereas the Jonckheere–Terpstra trend test was used to analyze ordinal qualitative scores.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Qualitative analysis confirmed no significant differences in body weight across groups. Evaluation of filter settings revealed that among the different spectral CT filter settings, YC and YD produced images with superior sharpness. Conversely, quantitative analysis showed that the filter settings (YC, YD) generated significantly higher noise levels than those of A, B, C, and F. For slice thickness, qualitative assessments preferred the images at 0.67 mm. The analysis of VMIs suggested that 40-keV images had better qualitative quality. Interestingly, quantitative metrics showed that these 40-keV images had the lowest SNR and lung parenchymal CNR among all the energy levels tested.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our study revealed an apparent paradox between qualitative and quantitative assessments of image quality. Combining the YC/YD filter settings, a 0.67 mm slice thickness, and 40-keV VMIs significantly enhances the Philips spectral CT image quality of mouse chests.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147616653","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":"Comparing deep learning stroke segmentation in NCCT, CTA, and CTP: Accuracy, domain transfer, and temporal sampling effect","authors":"Linda Vorberg,&nbsp;Hendrik Ditt,&nbsp;Andreas Maier,&nbsp;Savvas Nicolaou,&nbsp;Nicolas Murray,&nbsp;Oliver Taubmann","doi":"10.1002/mp.70419","DOIUrl":"10.1002/mp.70419","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;Stroke imaging typically involves multiple CT image types—non-contrast CT (NCCT), CT angiography (CTA), and CT perfusion (CTP). CTP and multiphase CTA (mCTA) are more advanced acquisitions with multiple timesteps and provide insights on the hemodynamics within the brain. Deep Learning models can help facilitate the diagnostic workflow by automatically identifying the extent of core and penumbra, which influences subsequent treatment decisions. For the use in clinical practice, generalizability of these models to new clinical sites is crucial.&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 evaluate and compare the usefulness of NCCT, CTA, mCTA, and CTP images for DL-based stroke lesion segmentation, with the aim of guiding modality selection in settings with and without access to advanced imaging, and with an additional focus on model transferability between clinical sites and the impact of time point selection from the CTP scan.&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 experiments involve model training with a dataset of 91 stroke patients from one clinical site. NCCT, CTA, mCTA, and CTP are used separately to train nnU-Net models for segmentation of stroke core and hypoperfused volume using uncertainty-aware labels. To assess site transferability, a model (pre-)trained on 166 cases from a second clinical site is employed to perform as-is inference with data from the first site, then contrast it with a variant of the model fine-tuned using a subset of the data from the first site. Multiple temporal sampling strategies were investigated for the 4D CTP data, choosing different subsets of the time series as the model input.&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;For automatic segmentation of stroke core, advanced imaging techniques yield improved accuracy with the modified Dice coefficient increasing from &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0.36&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.28&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$0.36pm 0.28$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; (NCCT) to &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0.55&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.27&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt;$0.55pm 0.27$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; (CTA), &lt;span","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13049103/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147616656","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":"Direct optimization of the probability of lesion origin in proton treatment planning for low-grade glioma patients","authors":"Tim Ortkamp,&nbsp;Habiba Sallem,&nbsp;Semi Harrabi,&nbsp;Martin Frank,&nbsp;Oliver Jäkel,&nbsp;Julia Bauer,&nbsp;Niklas Wahl","doi":"10.1002/mp.70395","DOIUrl":"10.1002/mp.70395","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;In proton therapy of low-grade glioma (LGG) patients, contrast-enhancing brain lesions (CEBLs) on magnetic resonance imaging are considered predictive of late radiation-induced lesions. From the observation that CEBLs tend to concentrate in regions of increased dose-averaged linear energy transfer (LET&lt;sub&gt;d&lt;/sub&gt;) and proximal to the ventricular system, the probability of lesion origin (POLO) model has been established as a multivariate logistic regression model for the voxel-wise probability prediction of the CEBL origin.&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 date, leveraging the predictive power of the POLO model for treatment planning relies on hand tuning the dose and LET&lt;sub&gt;d&lt;/sub&gt; distribution to minimize the resulting probability predictions. In this paper, we therefore propose automated POLO model-based treatment planning by directly integrating POLO calculation and optimization into plan optimization for LGG patients.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Approach&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;We introduce an extension of the original POLO model including a volumetric correction factor, and a model-based optimization scheme featuring a linear reformulation of the model together with feasible optimization functions based on the predicted POLO values. The developed framework is implemented in the open-source treatment planning toolkit matRad.&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;Our framework can generate clinically acceptable treatment plans while automatically taking into account outcome predictions from the POLO model. It also supports the definition of customized POLO model-based objective and constraint functions. Optimization results from a sample LGG patient show that the POLO model-based outcome predictions can be minimized under expectable shifts in dose, LET&lt;sub&gt;d&lt;/sub&gt;, and POLO distributions, while sustaining target coverage (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;Δ&lt;/mi&gt;\u0000 &lt;mtext&gt;PTV&lt;/mtext&gt;\u0000 &lt;/msub&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;D95&lt;/mtext&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;RBE&lt;/mi&gt;\u0000 &lt;mo&gt;,&lt;/mo&gt;\u0000 &lt;mi&gt;fx&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;≈&lt;/mo&gt;\u0000 &lt;mn&gt;0.00&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13049132/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147616953","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":"On the shape of the radiation survival curve in tumor spheroids: The role of oxygen heterogeneity","authors":"Uwe Schneider,&nbsp;Ning Liang,&nbsp;Jürgen Besserer","doi":"10.1002/mp.70425","DOIUrl":"10.1002/mp.70425","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 shape of cell survival curves at the tissue level remains an open question in radiobiology. While homogeneous cell populations (so-called single cells) typically exhibit an exponential decrease in survival with increasing dose, it is unclear whether this behavior persists in multicellular systems, where oxygen and nutrient gradients introduce additional complexity.&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 investigates how oxygen diffusion and consumption in tumor spheroids modify the aggregate radiation response and whether the resulting survival curves follow a purely exponential or a linear–quadratic (LQ) form on the logarithmic scale.&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;WiDr human colon adenocarcinoma cells were modeled using the track-event theory of cell survival. The parameters &lt;i&gt;p&lt;/i&gt; = 0.04 Gy&lt;sup&gt;−1&lt;/sup&gt;, &lt;i&gt;q&lt;/i&gt; = 0.70 Gy&lt;sup&gt;−1&lt;/sup&gt;, and &lt;i&gt;OER&lt;sub&gt;max&lt;/sub&gt;&lt;/i&gt; = 3.44 were obtained by fitting oxic and anoxic single-cell data from West et al. Oxygen tension profiles &lt;i&gt;pO2(r)&lt;/i&gt; in spheroids were calculated according to the diffusion–consumption model of &lt;i&gt;Grimes et al.&lt;/i&gt; using &lt;i&gt;p&lt;sub&gt;0&lt;/sub&gt;&lt;/i&gt; = 150 Torr, &lt;i&gt;r&lt;sub&gt;l&lt;/sub&gt;&lt;/i&gt; = 216 µm, and &lt;i&gt;a&lt;/i&gt; = 1.27×10&lt;sup&gt;−6&lt;/sup&gt; m&lt;sup&gt;3&lt;/sup&gt; kg s&lt;sup&gt;−1&lt;/sup&gt;. Oxygen-dependent, location-specific cellular radiosensitivity was modeled via the oxygen enhancement ratio (&lt;i&gt;OER&lt;/i&gt;), and the overall spheroid survival fraction was obtained by integrating survival over the viable spheroid volume, using both numerical calculation and a closed-form analytical approximation.&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;Both the mechanistic oxygen–diffusion–based numerical survival model and the simplified approximation reproduced experimental survival data for WiDr spheroids of diameters 100–1200 µm reported by Buffa et al. and West et al. The predicted survival curves become progressively less steep as spheroid size increases, reflecting the larger hypoxic fraction. For large spheroids, both model and data exhibit a distinct &lt;i&gt;upward curvature&lt;/i&gt; of the survival curve at high doses, deviating from both exponential and downward-bending LQ behavior. This effect arises from dose-dependent weighting of oxic and hypoxic cell subpopulations within the heterogeneous spheroid.&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 results support the hypothesis that oxygen heterogeneity fundamentally alters the apparent dose–re","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13048877/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147617007","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":"The end of browsing, continuous publication, and title scrutiny","authors":"John M. Boone,&nbsp;Stanley H. Benedict","doi":"10.1002/mp.70400","DOIUrl":"10.1002/mp.70400","url":null,"abstract":"&lt;p&gt;&lt;i&gt;Medical Physics&lt;/i&gt; has changed the way articles are published. In the past, once accepted after peer review, manuscripts were signed off by the authors (in the galley proof stage), they underwent final markup by the publisher, were queued up during the month and near the end of the month, that monthly issue was published. In each monthly issue, containing from 30 to 70 articles, the articles were placed in appropriate categories (selected by the authors during manuscript submission) such as &lt;i&gt;Quantitative Imaging and Image Processing&lt;/i&gt;, &lt;i&gt;Emerging Imaging and Therapy Modalities&lt;/i&gt;, &lt;i&gt;Computational and Experimental Dosimetry&lt;/i&gt;, and so on. This categorical organization allowed readers to browse the topics that they were interested in. In the era of print-only publication, a medical physicist might find some uninterrupted time to skim through the paper journal—fan the pages, check out this month's offerings, see who was publishing and on what topic—maybe even read two or three articles that were of interest. A seat on a jet airplane was one of our favorite places to browse the journal. Alas, this kind of relaxed browsing went away with the demise of the printed page.&lt;/p&gt;&lt;p&gt;When the journal went online only (Volume 51 in January 2024), the process was basically the same as with the print journal; however, flipping the printed page was replaced with a less aesthetic electronic scroll through the website. Nevertheless, the articles were still arranged in categories which allowed the readers to perform a more targeted review of the Table of Contents, and a mouse click got you to an article of interest if you were logged in.&lt;/p&gt;&lt;p&gt;Now, this too has changed. Wiley, our publisher, has moved to a new continuous publication model for the journal—and this is apparently consistent with the way the publishing industry is going. With the continuous publication model, as soon as accepted articles are signed off by the authors (after galley proof corrections) and receive final markup by the publisher, they are placed into a continuous stream of articles in the online viewing portal. The articles are no longer placed in the various categories as before; their arrangement is no longer a neatly arranged Table of Contents, but rather the order of articles on the website is simply a temporal stream as they are finalized by Wiley. So, the articles are extruded onto the website continuously, with the article feed severed at the end of the month to allow for the concept of “Monthly Issues” to endure. No more browsing the categories—they are gone as a means of organizing articles as of April 1, 2026, and while some previous issues will still have the associated category indicated above each article, more recently we have done away with listing scientific categories altogether since they provide no organizational function.&lt;/p&gt;&lt;p&gt;So, with the move to a continuous publication model, the notion of browsing the &lt;i&gt;Medical Physics&lt;/i&gt; journal is largely lost. One ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://aapm.onlinelibrary.wiley.com/doi/epdf/10.1002/mp.70400","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147617036","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":"Assessing variations in 3D image quality in chest CT across sites and scanners","authors":"Andrew M. Hernandez,&nbsp;Ali Uneri,&nbsp;Nicholas Bevins,&nbsp;Kalpana Kanal,&nbsp;David Zamora,&nbsp;Mark Supanich,&nbsp;Benjamin Maloney,&nbsp;Mahadevappa Mahesh,&nbsp;Michael F. McNitt-Gray,&nbsp;Paul Kinahan,&nbsp;Jeffrey H. Siewerdsen,&nbsp;John M. Boone","doi":"10.1002/mp.70402","DOIUrl":"10.1002/mp.70402","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;Large CT image databases are critical to the development and validation of protocol harmonization strategies and AI models. However, image quality (IQ) can vary significantly due to differences in technology and site practices, even for scanners from the same manufacturer, which can have considerable effects on harmonization efforts and AI algorithm development. Quantifying the 3D IQ variability represented in these databases is essential to characterize protocol heterogeneity, the training data distribution, and to assess test data overlap.&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 quantify and characterize sources of 3D IQ variability in chest CT across scanner models and imaging sites.&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 previously-reported phantom and its automated analysis software was employed across 6 sites, 3 CT manufacturers, and 27 scanners (10 unique models) to rigorously quantify IQ metrics, including image noise, image contrast (low-contrast objects: −26 HU, 41 HU; medium: −84 HU; high: 276 HU, 817 HU), the 3D MTF (axial plane and oblique direction), and the 3D NPS. The MTF was summarized using the frequency at 10% modulation “&lt;i&gt;f&lt;/i&gt;&lt;sub&gt;10&lt;/sub&gt;”, and NPS using average frequency “&lt;i&gt;f&lt;/i&gt;&lt;sub&gt;avg&lt;/sub&gt;”. Sites were instructed to use their non-contrast chest CT protocols for fixed mAs phantom scanning at CTDI&lt;sub&gt;vol,32&lt;/sub&gt; levels of 2.1 (low dose “LD”), 4.2 (MD), and 6.3 mGy (HD), and provide four reconstructions, including standard ‘Std’ and thin ‘Thn’ slice thicknesses for sharp “Sh” and soft “So” kernels. Variance component analysis (VCA) was performed on the resulting phantom series to quantify sources of variability in IQ partitioned into inter-scanner model, inter-site, and residual (i.e., unexplained) components.&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;IQ metrics dominated by inter-scanner differences (&gt; 50% of total variance) included image noise for Sh-Std-LD/MD, Sh-Thn-LD, and So-Std/Thn for all doses (51%–84%), high-contrast (276, 817 HU) image contrast for all protocols (68%–93%), medium-contrast image contrast for all MD/HD protocols (64%–88%), low-contrast (−26 HU) image contrast for So-Std-MD (65%) and Sh-Std-LD/MD (64%/51%), axial and oblique &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;annotation&gt;${{f}_{10}}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; for nearly all protocols (58%–88% and 56%–58%, respectively), axial &lt;i&gt;f&lt;/i&gt;&lt;sub&gt;avg&lt;/sub&gt; for Sh-Thn across all dose le","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147597044","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":"Monte Carlo–based optimization of CTV-to-PTV margins for image-guided VMAT prostate radiotherapy","authors":"Quan Chen,&nbsp;Ali Ammar,&nbsp;Nathan Y. Yu,&nbsp;Libing Zhu,&nbsp;Yi Rong,&nbsp;Carlos E. Vargas","doi":"10.1002/mp.70415","DOIUrl":"10.1002/mp.70415","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>The van Herk margin formula, derived for 3-D conformal radiotherapy with a uniform 3.2 mm dose penumbra and no intrinsic dose buffer, remains widely used to design CTV-to-PTV expansions in contemporary image-guided prostate radiotherapy. However, coplanar VMAT techniques often feature broader penumbrae and explicit PTV–isodose clearances, potentially violating the assumptions underlying the original formulation and leading to overly conservative margins.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>We investigated whether the widely adopted van Herk margin formula overestimates clinical target volume (CTV)-to-planning target volume (PTV) expansions for contemporary coplanar volumetric modulated arc therapy (VMAT) prostate treatments.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Fifty consecutive intact-prostate VMAT radiotherapy plans (two coplanar arcs; clinical margins 3 mm, except for 2 mm posterior) were exported. Direction-specific 90% isodose–to-PTV gaps and penumbra widths were measured. Candidate anisotropic margins were tested by eroding the PTV to create CTV_eval. Monte-Carlo simulations combined systematic (Σ) shifts with Gaussian random (σ′) blurring kernels of 0–2 mm were performed. Acceptability criteria of (i) CTV Dmin0.03 cc ≥ 90% Rx in ≥ 90% of simulated scenarios or (ii) population tumor-control probability (TCP) loss &lt; 1 % were used.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>VMAT plans exhibited intrinsic 90% isodose clearances of 3–5 mm laterally/anteriorly and 1–2 mm superior–inferiorly, while axial-plane penumbras were up to fivefold broader than van Herk's assumption. With a [0, 0, 2] mm (LR/AP/SI) margin, ≥ 90% of patients maintained Dmin0.03 cc ≥ 90% Rx provided Σ lay within an ellipsoid of [2.0, 1.5, 1.8] mm and σ′ ≤ [1.5, 2.0, 1.5] mm. Under TCP criteria the safe Σ ellipsoid for high-risk disease was [2.5, 1.9, 2.2] mm, while low-intermediate risk was even less sensitive.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>For image-guided coplanar VMAT prostate radiotherapy, an anisotropic [0, 0, 2] mm CTV-to-PTV margin is sufficient for target coverage. A modified margin expression that subtracts the measured isodose–to-PTV gap and uses reduced random-error coefficients better reflects modern practice.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147583500","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":"Integrated optimization of needle paths and dwell time for individualized template-guided interstitial brachytherapy","authors":"Qinglong Yao,&nbsp;Kaiyue Wang,&nbsp;Bo Liu,&nbsp;Ping Jiang,&nbsp;Fugen Zhou,&nbsp;Junjie Wang,&nbsp;Qiuwen Wu","doi":"10.1002/mp.70411","DOIUrl":"10.1002/mp.70411","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;3D-printed individualized template (3D-PIT) guided interstitial brachytherapy (ISBT) is an effective treatment modality for cervical cancer. However, the current practice of pre-operative planning requires manual needle paths design, which is highly dependent on operator experience and may lead to unnecessary insertion trauma.&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 this issue, this study introduces and validates an automated integrated optimization method for needle paths and dwell times for an institutional protocol of 3D-PIT based ISBT for locally recurrent cervical cancer.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods and Materials&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;To automatically generate a treatment plan, a candidate needle path set was first generated based on patient's anatomy and the transvaginal template. Then, a two-layer optimization strategy was introduced for automated integrated optimization of the needle paths and dwell times, with the outer layer employing simulated annealing to optimize the needle paths, and the inner layer to optimize the dwell times. A total of 40 patient cases (with the prescribed dose to HR-CTV D&lt;sub&gt;90%&lt;/sub&gt; being 6 Gy (physical dose) per fraction, and 2–8 fractions per case, totaling 219 independent fraction plans) with locally recurrent cervical cancer previously treated with 3D-PIT-assisted ISBT were enrolled in this study. Automatic plans for all fractions were generated and evaluated using the same number of needles as in the clinical plans, with the dosimetric results of the clinical plans used as constraints. In addition, the quality of automatic plans using fewer needles was also investigated.&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 method generated clinically acceptable plans in 1.5 ± 1.2 min, requiring 145 ± 74 iterations, according to institutional protocols based on the EMBRACE II. In terms of dosimetric quality, the automatic plans met the constraints and generally outperformed the clinical plans in protecting organs-at-risk (OARs). When normalizing both plans to the same HR-CTV D&lt;sub&gt;90%&lt;/sub&gt; and comparing the dosimetric outcomes of OARs, the D&lt;sub&gt;2cc&lt;/sub&gt; of rectum, bladder, colon, and small intestine were reduced from 363 to 350 cGy, 397 to 376 cGy, 226 to 204 cGy, and 140 to 123 cGy, respectively (all &lt;i&gt;p&lt;/i&gt; &lt; 0.001). The D&lt;sub&gt;0.1cc&lt;/sub&gt; of urethra was reduced from 406 to 351 cGy (&lt;i&gt;p&lt;/i&gt; &lt; 0.001). V&lt;sub&gt;100%&lt;/sub&gt; of HR-CTV remained the same at 78% (&lt;i&gt;p&lt;/i&gt; = 0.28), and V&lt;sub&gt;150%&lt;/sub&gt; of HR-CTV was increased from 42% to 44% (&lt;i&gt;p&lt;/i&gt; &lt; 0.001). Total dwell time decreased from 278 to 271 seconds (&lt;i&gt;p&lt;/i&gt; &lt; 0.001). In ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147583502","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":"Pushing the limits of spatial resolution in clinical PCD-CT using a dedicated high-resolution convolutional neural network (HR-CNN)","authors":"Zhongxing Zhou,&nbsp;Alex K. Bratt,&nbsp;Chi Wan Koo,&nbsp;Kelly K. Horst,&nbsp;Cynthia H. McCollough,&nbsp;Lifeng Yu","doi":"10.1002/mp.70382","DOIUrl":"10.1002/mp.70382","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;Photon-counting-detector (PCD) CT systems offer ultra-high spatial resolution, yet the visual spatial resolution on clinical images often constrained by large pixel size, yielding resolutions below system capabilities. While reducing pixel size and using sharp kernels enhance visual spatial resolution, it increases noise, compromising image quality.&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 investigate the combined effects of pixel size and reconstruction kernels on visual spatial resolution using phantom and clinical images and to develop a dedicated high-resolution deep convolutional neural network (HR-CNN) to better utilize the intrinsic high spatial resolution of PCD-CT in clinical imaging.&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 relationship between spatial resolution, reconstruction kernel, and pixel size was investigated to identify strategies for utilizing the full spatial resolution potential of PCD-CT. To overcome the increased noise associated with high-resolution settings, a dedicated HR-CNN was developed to push the limit of spatial resolution in routine PCD-CT exams. The HR-CNN was trained using patient exams acquired with ultra-high-resolution (UHR) mode and reconstructed with a 150-mm field of view (FOV), matrix size of 1024×1024 (0.15-mm pixel size) and sharpest quantitative kernel (Qr89). The impact of FOV, kernel, and denoising on spatial resolution was studied using bar-pattern phantoms and a pilot clinical evaluation including 5 patients with interstitial lung diseases. Two thoracic radiologists evaluated 4 different FOV/reconstruction conditions: (1) FOV-410/Qr56-Iterative reconstruction (IR), (2) FOV-410/Qr89-IR, (3) FOV-150/Qr89-IR, and (4) FOV-150/Qr89-HR-CNN in terms of overall image quality, noise, visual spatial resolution, and overall preference.&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;With a FOV of 410 mm, the Qr89 sharp kernel displayed bar-patterns up to 14 lp/cm, not much higher than the routine lung kernel Qr56. When the FOV was reduced to 150 mm, Qr89-IR allowed for the visualization of line pair patterns ranging from 18 to 20 lp/cm, with 20 lp/cm being moderately discernible. The application of Qr89-HR-CNN yielded further improvement, enabling the display of line pair patterns as high as 20–22 lp/cm. In patient cases, both radiologists consistently ranked the FOV-150 images processed with HR-CNN as superior across metrics including overall image quality, noise reduction, visual spatial resolution, and overall preference. The HR-CNN reduced the noise in patients’ images by 93.0 ± 0.6% and 44.9 ± 5.3% in comparison with the original FB","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"53 4","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147577401","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}