Physics and Imaging in Radiation Oncology最新文献

{"title":"Proton Bragg peak flash stereotactic radiosurgery for recurrent glioblastoma reirradiation","authors":"Yangguang Ma,&nbsp;Yuyu Wang,&nbsp;Tengda Zhang,&nbsp;Xingyi Zhao,&nbsp;Balaji Selvaraj,&nbsp;Chingyun Cheng,&nbsp;Michael Pennock,&nbsp;Jocelyn Jackson,&nbsp;Wei Guo,&nbsp;Xuanqin Mou,&nbsp;Benjamin Durkee,&nbsp;Jehee Isabelle Choi,&nbsp;Haibo Lin,&nbsp;Charles B. Simone II,&nbsp;Minglei Kang,&nbsp;Hui Wu","doi":"10.1016/j.phro.2026.101044","DOIUrl":"10.1016/j.phro.2026.101044","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Stereotactic Radiosurgery with robotic image-guided systems is promising for recurrent glioblastoma (rGBM), but long delivery times may increase morbidity and reduce accuracy. Proton single-energy Bragg-peak FLASH-RT (SEBP-FLASH) may address these limits by delivering each field in &lt;1 s, with potential for normal-tissue sparing through the FLASH effect.</div></div><div><h3>Materials and Methods</h3><div>The SEBP-FLASH technique was used to reoptimize treatment for rGBM patients treated with robotic image-guided systems. Patient-specific aperture devices were incorporated into the SEBP-FLASH technique for sharper penumbra. The gross tumor volume (GTV) coverage, conformity index (CI), dose gradient index (GI₅₀ and GI₃₀), and dose-volume histogram (DVHs), were evaluated. Additionally, ultra-high dose-rate ratios in critical organs-at-risk were assessed.</div></div><div><h3>Results</h3><div>SEBP-FLASH successfully met all clinical objectives. Both SEBP-FLASH and robotic techniques showed comparable performance, with GI₅₀ and GI₃₀ values of 2.9 ± 0.5 and 6.2 ± 1.8 for SEBP-FLASH, versus 2.7 ± 0.2 and 5.5 ± 0.5 for robotic (<em>p</em>-values at 0.085 and 0.189). SEBP-FLASH demonstrated superior conformality, achieving a CI of 1.4 ± 0.2 compared to CK's 1.9 ± 0.3 (p-value 0.001). All other metrics were similar across both techniques. For the brain, the FLASH dose rate coverage (V_{40 Gy/s}) exceeded 80% under a 5 Gy dose threshold and minimum monitor unit of 400.</div></div><div><h3>Conclusions</h3><div>This study evaluated the dose-volume characteristics of SEBP-FLASH and robotic image-guided systems and found broadly comparable dose distributions, suggesting that SEBP-FLASH may be a feasible option for rGBM reirradiation. SEBP-FLASH also showed potential advantages in conformity, normal tissue sparing, and reduced on-table time.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101044"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148739232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clinical indicators for dose re-optimization in magnetic resonance-guided online adaptive radiotherapy for prostate cancer","authors":"Masato Nishitani,&nbsp;Hiroyuki Okamoto,&nbsp;Weishan Chang,&nbsp;Junichi Kuwahara,&nbsp;Takahito Chiba,&nbsp;Tatsuya Sakasai,&nbsp;Hiroki Nakayama,&nbsp;Koji Inaba,&nbsp;Tairo Kashihara,&nbsp;Satoshi Nakamura,&nbsp;Tetsu Nakaichi,&nbsp;Tomonori Goka,&nbsp;Hiroshi Igaki","doi":"10.1016/j.phro.2026.101060","DOIUrl":"10.1016/j.phro.2026.101060","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>This study aimed to identify dose-volume parameters and anatomical features associated with the implementation of online dose re-optimization in magnetic resonance-guided adaptive radiotherapy (ART) for prostate cancer and to evaluate its impact on target coverage and organs-at-risk dose-volume parameters.</div></div><div><h3>Materials and Methods</h3><div>Treatment plans from 150 fractions (with and without dose re-optimization) in 30 patients receiving five-fraction stereotactic body radiotherapy were retrospectively analyzed. Evaluated parameters included planning target volume (PTV) <em>V</em>_100%, bladder and rectum dose-volume parameters, volumetric changes, and relationship between changes in target coverage.</div></div><div><h3>Results</h3><div>Online dose re-optimization was performed in 60% of fractions and became more frequent in later fractions (<em>p</em> = 0.02). Compared with reference plans, non-ART plans showed a 3.7% lower median PTV <em>V</em>_100% (<em>p</em> &lt; 0.01), and 65.3% of fractions failed to achieve the 95% coverage threshold. The target volume increased significantly after the third fraction (<em>p</em> &lt; 0.05). Target volume expansion was associated with reductions in PTV <em>V</em>_100% in non-ART plans, while this relationship was substantially weakened after dose re-optimization. Although bladder and rectum dose-volume parameters increased significantly in non-ART plans, all median values remained within predefined dose constraints.</div></div><div><h3>Conclusions</h3><div>Progressive target-volume expansion appears to be the primary anatomical factor associated with deterioration in target coverage. A reduction in PTV <em>V</em>_100%, particularly below 95%, represented a clinically meaningful indicator for online dose re-optimization. These findings suggested that online dose re-optimization remained important for maintaining target coverage and limiting gradual deterioration of organs-at-risk dose-volume parameters, even when predicted plans satisfied clinical constraints.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101060"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148776978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Erratum to “Identifying the optimal time point for adaptive re-planning in prostate cancer radiotherapy to minimise rectal toxicity using normal tissue imaging biomarkers” [Phys. Imaging Radiat. Oncol. 36 (2025) 100850]","authors":"Zhuolin Yang,&nbsp;David J. Noble,&nbsp;Sarah Elliot,&nbsp;Leila Shelley,&nbsp;Thomas Berger,&nbsp;Raj Jena,&nbsp;Duncan B. McLaren,&nbsp;Neil G. Burnet,&nbsp;William H. Nailon","doi":"10.1016/j.phro.2026.101061","DOIUrl":"10.1016/j.phro.2026.101061","url":null,"abstract":"","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101061"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148854179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved synthetic CT generation using surface scan information integrated into a deformable registration algorithm for limited Field of View data","authors":"Joachim Marichal,&nbsp;Stina Svensson,&nbsp;Geert De Kerf,&nbsp;Ola Weistrand,&nbsp;Mattias Nilsing,&nbsp;Michaël Claessens,&nbsp;Pelle Jansson,&nbsp;Dirk Verellen","doi":"10.1016/j.phro.2026.101050","DOIUrl":"10.1016/j.phro.2026.101050","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Cone-Beam Computed Tomography (CBCT) based synthetic CT is being increasingly used for post-delivery dose computation or adaptive workflows in radiotherapy. However, the limited Field-of-View of the CBCT can cause inaccuracies when tissues fall outside the Field of View. This study evaluates the integration of surface-guided radiotherapy information to enhance synthetic CT generation for breast cases with missing tissues on CBCT.</div></div><div><h3>Materials and Methods</h3><div>A retrospective analysis was performed on 20 breast patients. CBCT volumes were acquired on a linac, with simultaneous surface scans from three cameras. A full Field of View CBCT was used to generate a reference synthetic CT. A smaller Field of View CBCT was reconstructed from the same raw data to create two synthetic CTs: a standard synthetic CT and a surface-guided synthetic CT, for which surface scan information was incorporated into the algorithm to guide reconstruction outside the Field of View. We compared the image similarity, external contour geometry, and dose distribution.</div></div><div><h3>Results</h3><div>The surface-guided synthetic CT showed superior agreement with the reference for nine tested metrics. Specifically, it showed an average Mean Squared Error reduction of 1963 HU<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> (<span><math><mrow><mi>p</mi><mo>=</mo><mn>0.002</mn></mrow></math></span>), revealing hot spots in some cases.</div></div><div><h3>Conclusion</h3><div>Integrating surface scan information into deformable registration improves synthetic CT generation for CBCT with limited Field of View, yielding more accurate images and enhanced dose distribution precision for breast cases. Future work will explore other sites, and potential applications for adaptive radiotherapy.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101050"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148651394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of dose reporting modes on dosimetric accuracy in a national end-to-end stereotactic spine radiotherapy audit","authors":"Rushil Patel,&nbsp;Mohammad Hussein,&nbsp;Jonny Lee,&nbsp;Patricia Diez,&nbsp;Ileana Silvestre Patallo,&nbsp;Hannah Cook,&nbsp;Alexandros Douralis,&nbsp;Catharine H. Clark","doi":"10.1016/j.phro.2026.101041","DOIUrl":"10.1016/j.phro.2026.101041","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Spinal Stereotactic Body Radiotherapy (SBRT) is among the most complex treatments currently delivered. A multi-centre dosimetry audit evaluated the accuracy of spinal SBRT treatment delivery and the impact of different dose reporting modes (DRM).</div></div><div><h3>Methods and materials</h3><div>The audit used anthropomorphic phantoms containing alanine in the Planning Target Volume (PTV) and Gafchromic™ EBT3 film in the axial plane, with a combination of onsite and remote audits due to Covid travel restrictions. Centres used their local planning protocol and technique to create a clinically acceptable treatment plan, following national guidance.</div></div><div><h3>Results</h3><div>Fifty-nine plans from 44 treatment planning systems at 41 centres were analysed. The mean PTV dose difference was 1.2% [−6.5–8.5%] with alanine and 1.0% [−7.0–8.5%] within the 100% isodose for film. Alanine measurements were, on average, higher than the calculated dose for all plans, but lower for the D_w,m specifically. For alanine and film, the choice of DRM was statistically significant.</div><div>The mean distance to agreement and average Centre of Dose difference for films was 0.82 mm [0.35–1.7 mm] and 0.78 mm [0.1–1.7 mm] respectively. The choice of DRM was not significant for either metric.</div></div><div><h3>Conclusions</h3><div>This audit demonstrated that the majority of centres are delivering spinal SBRT consistently, with acceptable dosimetric and geometric accuracy. However, it also highlighted the challenges of verifying doses reported in D_m,m and D_w,m, as there was a statistically significant difference with the measured dose when stratified by DRM.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101041"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148651395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of an artificial intelligence driven dose prediction pipeline for online adaptive magnetic resonance-guided radiotherapy","authors":"Benjamin Tengler,&nbsp;Moritz Schneider,&nbsp;Marcel Nachbar,&nbsp;Simon Boeke,&nbsp;Cihan Gani,&nbsp;Maximilian Niyazi,&nbsp;Paul Fischer,&nbsp;Christian F. Baumgartner,&nbsp;Daniela Thorwarth","doi":"10.1016/j.phro.2026.101048","DOIUrl":"10.1016/j.phro.2026.101048","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>The closed-off nature of most treatment planning systems (TPS) limits the potential for using artificial intelligence (AI) tools during online adaptive treatments. The aim of this study was to develop an AI-driven pipeline (AutoAdapt) for online planning of adaptive radiotherapy usable in a closed-off setting, providing optimal plan constraints derived from a population-based dose prediction model.</div></div><div><h3>Material and methods</h3><div>The AutoAdapt pipeline consists of a physics-aware Swin UNet transformer network for dose prediction trained on 266 magnetic resonance images from 25 prostate cancer patients treated with 60 Gy on a 1.5 T magnetic resonance linear accelerator. The predicted dose was used to calculate plan constraints that were subsequently fed into a commercial TPS. AutoAdapt was tested using ten unseen cases and compared to manual plans based on clinical objectives, time, and complexity.</div></div><div><h3>Results</h3><div>While all plans were approved by a radiation oncologist, AutoAdapt met all clinical objectives in seven patients compared to ten when manually planned. AutoAdapt yielded a significantly lower D_0.035cm³ to the rectum (<em>p</em> = 0.01). Manual plans achieved a median rectum V_20Gy of 44% compared to 51% in AutoAdapt plans (<em>p</em> = 0.02). The pipeline only required a median of 29 s (7.5%) longer than the manual planners.</div></div><div><h3>Conclusions</h3><div>The developed pipeline resulted in high-quality plans, ready for clinical use without further adjustments. AutoAdapt prioritized maximum rectum dose over D_20% compared to manual planning, while requiring less manual work. In the future, AutoAdapt may be used to assist human planners and improve adaptive radiotherapy workflows.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101048"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148658292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of experimental and radiobiological model-predicted survival of human laryngeal squamous cell carcinoma cells in a helium spread-out Bragg peak","authors":"Thomas Berger,&nbsp;Gersende Alphonse,&nbsp;Mario Alcocer-Avila,&nbsp;Caterina Monini,&nbsp;Charbel Koumeir,&nbsp;Claire Rodriguez-Lafrasse,&nbsp;Flavien Ralite,&nbsp;Nicolas Varmenot,&nbsp;Noel Servagent,&nbsp;Vincent Métivier,&nbsp;Ferid Haddad,&nbsp;Alexis Pereda,&nbsp;Lydia Maigne,&nbsp;Jean Michel Létang,&nbsp;Étienne Testa,&nbsp;Michaël Beuve","doi":"10.1016/j.phro.2026.101047","DOIUrl":"10.1016/j.phro.2026.101047","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Helium ion therapy offers favorable dose distributions and potential biological advantages over photon and proton therapies, yet data on cellular response in clinically relevant Spread-Out Bragg Peak (SOBP) configurations remain limited. This study measured the surviving fraction of radioresistant human laryngeal squamous cell carcinoma (SQ20B) cells irradiated in a helium SOBP and compared experimental results with predictions from NanOx, a nanodosimetry and oxidative stress model implemented in Monte Carlo simulations.</div></div><div><h3>Materials and Methods</h3><div>SQ20B cells were irradiated at three positions along a helium SOBP using a passive beamline. Survival fractions were measured for doses between 1 and 4 Gy. The setup was simulated in GATE, and survival was predicted using the NanOx model via the Biodose Actor. Relative biological effectiveness (RBE) was derived from linear quadratic fits using photon reference parameters.</div></div><div><h3>Results</h3><div>NanOx predicted decreasing survival towards the distal edge, with surviving fractions at 4 Gy of 11%, 7%, and 4% at the proximal edge, plateau, and distal edge, respectively. Experimentally, fitted surviving fractions at 4 Gy were 10%, 12%, and 8%, showing no spatial trend. Deviations between model predictions and experimental averages ranged from 20 to 37%. Experimental RBE values ranged from 2.1 to 2.4, in reasonable agreement with NanOx predictions (2.1–2.9).</div></div><div><h3>Conclusions</h3><div>In this SQ20B cell model under the present experimental conditions, NanOx predictions differed from experimental data by 20–37% depending on position. These results support further validation of the model in a broader range of cell lines and helium ion irradiation configurations.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101047"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148738716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From local validation to global standardization of three-dimensional printing in radiotherapy","authors":"José Vedelago,&nbsp;Christina Stengl,&nbsp;Barbara Knäusl","doi":"10.1016/j.phro.2026.101053","DOIUrl":"10.1016/j.phro.2026.101053","url":null,"abstract":"","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101053"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148739234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative lung tissue functional analysis for pulmonary adverse event risk assessment prior to thoracic radiotherapy","authors":"Sean R. Miller,&nbsp;Daniel Polan,&nbsp;Chase Hadley,&nbsp;Karen Vineberg,&nbsp;Christina Lockhart,&nbsp;David N. O'Dwyer,&nbsp;Wassim W. Labaki,&nbsp;Craig J. Galban,&nbsp;Steven G. Allen,&nbsp;Martha Matuszak,&nbsp;Shruti Jolly,&nbsp;Krithika Suresh,&nbsp;Charles K. Matrosic","doi":"10.1016/j.phro.2026.101022","DOIUrl":"10.1016/j.phro.2026.101022","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Pulmonary adverse events are a limiting factor in thoracic radiotherapy and more common in patients with pulmonary comorbidities. Parametric response mapping (PRM) is an effective method of providing 3-dimensional underlying lung comorbidity data. We hypothesized that a commercial PRM software could identify patients at increased risk of pulmonary adverse events during radiotherapy.</div></div><div><h3>Materials and methods</h3><div>Paired inspiratory/expiratory computed tomography (CT) scans obtained during simulation were processed using Lung Density Analysis (LDA) to classify lung tissue as Normal, Functional Low Density (FLD), Persistent Low Density (PLD), and Inspiration High Density (IHD). Patients were classified as elevated FLD, PLD, or IHD using predetermined thresholds. Multivariable models investigated associations between grade ≥ 2 pulmonary adverse events and (i) LDA measures, and (ii) clinical lung disease history. Model discrimination was assessed using area under the receiver operating characteristic curve (AUC).</div></div><div><h3>Results</h3><div>Among 98 patients receiving definitive-intent thoracic radiotherapy, 22 experienced grade ≥ 2 pulmonary adverse events. Elevated IHD (Odds Ratio [OR] = 2.95; 95% Confidence Interval [CI]:1.12–7.97; <em>p</em> = 0.03) and PLD (OR = 2.32; 95%CI:0.80–6.52; <em>p</em> = 0.11) were associated with increased odds of adverse events. The LDA-based multivariable model demonstrated higher, but not significantly improved, discrimination than a model with lung disease history (apparent AUC 0.768 vs. 0.735; <em>p</em> = 0.47; optimism-corrected AUC 0.705 vs. 0.686).</div></div><div><h3>Conclusion</h3><div>Elevated IHD was a significant predictor of pulmonary adverse events, with PLD demonstrating a similar but nonsignificant trend. LDA measures demonstrated predictive performance comparable to clinical lung disease history, suggesting potential utility as a risk-screening tool pending validation in larger cohorts.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101022"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13324496/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148376375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A framework for planning organ at risk volume margin derivation for the small bowel during magnetic resonance-guided radiotherapy","authors":"Saskia L.C. Damen,&nbsp;Astrid L.H.M.W. van Lier,&nbsp;Cornel Zachiu,&nbsp;Martijn P.W. Intven,&nbsp;Bas W. Raaymakers","doi":"10.1016/j.phro.2026.101036","DOIUrl":"10.1016/j.phro.2026.101036","url":null,"abstract":"<div><h3>Background and Purpose:</h3><div>The small bowel is highly radiosensitive and prone to motion during abdominal and pelvic radiotherapy, risking overdosage. This study extended a previously presented small bowel tracking framework to enable automated planning organ at risk volume (PRV) margin derivation.</div></div><div><h3>Materials and Methods:</h3><div>MR scans were obtained in 18 patients treated for abdominal lesions, with abdominal compression. The mean motion, maximum displacement and position of the small bowel during the acquisition (7.5 min) were determined. The position of the small bowel over time was used to derive PRV margins based on geometrical coverage.</div></div><div><h3>Results:</h3><div>Displacements <span><math><mrow><mo>&gt;</mo><mn>20</mn></mrow></math></span> mm in the craniocaudal direction were observed, with approximately half of the bowel voxels experiencing positional displacements close to 10 mm. Despite this substantial motion, margin analysis demonstrated that applying a 4.5 mm isotropic margin around the delineated bowel loops was sufficient to cover 95% of the bowel voxels occupied for at least 5% of the time in 90% of the cases. It was shown that shorter acquisitions (2.5 min) already gave stable margin results, supporting the feasibility of using individualized PRV margins to balance motion coverage with treatment planning flexibility.</div></div><div><h3>Conclusions:</h3><div>While the small bowel can undergo considerable intrafraction displacements during treatment, most of this motion can be effectively encompassed using a moderate intrafraction PRV margin for this specific cohort. This study presents an automated framework to derive patient- and treatment-specific margins, directly from bowel tracking data, enabling tailored coverage-based margins.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101036"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148477864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}