Physics and Imaging in Radiation Oncology最新文献

{"title":"Implementation and clinical evaluation of an in-house thoracic auto-segmentation model for 0.35 T magnetic resonance imaging guided radiotherapy","authors":"Nikolaos Delopoulos ,&nbsp;Sebastian Marschner ,&nbsp;Elia Lombardo ,&nbsp;Marvin F. Ribeiro ,&nbsp;Paul Rogowski ,&nbsp;Christoph Losert ,&nbsp;Tobias Winderl ,&nbsp;Shadi Albarqouni ,&nbsp;Claus Belka ,&nbsp;Stefanie Corradini ,&nbsp;Christopher Kurz ,&nbsp;Guillaume Landry","doi":"10.1016/j.phro.2025.100819","DOIUrl":"10.1016/j.phro.2025.100819","url":null,"abstract":"<div><h3>Background and Purpose:</h3><div>Magnetic resonance imaging-guided radiotherapy (MRgRT) facilitates high accuracy, small margins treatments at the cost of time-consuming and labor-intensive manual delineation of organs-at-risk (OARs). Auto-segmentation models show promise in streamlining this workflow. This study investigates the clinical applicability of a set of thoracic OAR segmentation models for baseline treatment planning in lung tumor patients. We investigate the use of the models for treatment at a 0.35<!--> <!-->T MR-linac, assess their potential to reduce physician workload in terms of time savings and quantify the extent of required manual corrections, providing insights into the value of their integration into clinical practice.</div></div><div><h3>Materials and Methods:</h3><div>Deep-learning based auto-segmentation models for 9 thoracic OARs were integrated into the MRgRT workflow. Two groups of 11 lung cancer cases each were prospectively considered. For Group 1 auto-segmentation contours were corrected by physicians, for Group 2 manual contouring according to standard clinical workflows was performed. Contouring times were recorded for both. Time savings between the groups as well as correlations of the extent of corrections to correction times for Group 1 patients were analyzed.</div></div><div><h3>Results:</h3><div>The model performed consistently well across all Group 1 cases. Median contouring times were reduced for six out of nine OARs leading to a reduction of 50.3<!--> <!-->% or 12.6<!--> <!-->min in median total contouring time.</div></div><div><h3>Conclusion:</h3><div>Feasibility of auto-segmentation for baseline treatment planning at the 0.35<!--> <!-->T MR-linac was shown with significant time savings demonstrated. Time saving potential could not be estimated from model geometric performance metrics.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"35 ","pages":"Article 100819"},"PeriodicalIF":3.3,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144864779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An interactive deep-learning workflow for head and neck gross tumour volume segmentation","authors":"Zixiang Wei ,&nbsp;Jintao Ren ,&nbsp;Jesper Grau Eriksen ,&nbsp;Kenneth Jensen ,&nbsp;Hanna Rahbek Mortensen ,&nbsp;Stine Sofia Korreman ,&nbsp;Jasper Nijkamp","doi":"10.1016/j.phro.2025.100820","DOIUrl":"10.1016/j.phro.2025.100820","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Deep learning (DL)-based auto-segmentation of head and neck cancer (HNC) gross tumour volumes remains challenging due to anatomical complexity and limited accuracy. We propose an interactive DL (iDL) workflow that integrates clinician input to enhance segmentation performance and clinical usability. The iDL approach was evaluated using simulations on two datasets and an observer study.</div></div><div><h3>Materials and methods</h3><div>Two iDL approaches were developed and integrated into a workflow: (1) for primary tumour (GTVt) segmentation, clinicians marked the tumour centre and delineated three orthogonal slices to enable patient-specific fine-tuning of a pre-trained 3D UNet; (2) for lymph nodes (GTVn), clinician-provided clicks identified involved lymph nodes used as attention maps in a separate UNet. Methods were evaluated using independent simulations on an internal dataset (n = 204) and the HECKTOR 2022 dataset (n = 524), using aggregated dice-similarity-coefficient (DSCagg). An additional observer study with three radiation oncologists assessed usability and efficiency, using normalized added path length (APL) and the System Usability Scale (SUS).</div></div><div><h3>Results</h3><div>The iDL workflow achieved high segmentation accuracy, with a DSCagg of 0.84 (internal) and 0.88 (HECKTOR) for GTVt, and 0.83 and 0.85 for GTVn. GTVn required minimal correction (mean APL: 4 % vs. 6 % vs. 11 %); two observers made limited corrections to GTVt (mean APL: 11 % vs. 6 % vs. 39 %). Mean segmentation time was 12 min per case. SUS scores ranged from 87.5 to 100, indicating high usability.</div></div><div><h3>Conclusion</h3><div>The iDL workflow achieved high accuracy and usability with limited correction time, offering a practical and efficient solution for HNC segmentation in radiotherapy.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"35 ","pages":"Article 100820"},"PeriodicalIF":3.3,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144772927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Image-based mandibular and maxillary parcellation and annotation using computed tomography (IMPACT): a deep learning-based clinical tool for orodental dose estimation and osteoradionecrosis assessment","authors":"Laia Humbert-Vidan ,&nbsp;Austin H. Castelo ,&nbsp;Renjie He ,&nbsp;Lisanne V. van Dijk ,&nbsp;Dong Joo Rhee ,&nbsp;Congjun Wang ,&nbsp;He C. Wang ,&nbsp;Kareem A. Wahid ,&nbsp;Sonali Joshi ,&nbsp;Parshan Gerafian ,&nbsp;Natalie West ,&nbsp;Zaphanlene Kaffey ,&nbsp;Sarah Mirbahaeddin ,&nbsp;Jaqueline Curiel ,&nbsp;Samrina Acharya ,&nbsp;Amal Shekha ,&nbsp;Praise Oderinde ,&nbsp;Alaa M.S. Ali ,&nbsp;Andrew Hope ,&nbsp;Erin Watson ,&nbsp;Amy C. Moreno","doi":"10.1016/j.phro.2025.100817","DOIUrl":"10.1016/j.phro.2025.100817","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Accurate delineation of orodental structures on radiotherapy computed tomography (CT) images is essential for dosimetric assessment and dental decisions. We propose a deep-learning (DL) auto-segmentation framework for individual teeth and mandible/maxilla sub-volumes aligned with the ClinRad osteoradionecrosis staging system.</div></div><div><h3>Materials and methods</h3><div>Mandible and maxilla sub-volumes were manually defined on simulation CT images from 60 clinical cases, differentiating alveolar from basal regions; teeth were labelled individually. For each task, a DL segmentation model was independently trained. A Swin UNETR-based model was used for mandible sub-volumes. For smaller structures (e.g., teeth and maxilla sub-volumes) a two-stage model first used the ResUNet to segment the entire teeth and maxilla regions as a single ROI used to crop the image input for Swin UNETR. In addition to segmentation accuracy and geometric precision, a dose-volume comparison was made between manual and model-predicted segmentations.</div></div><div><h3>Results</h3><div>Segmentation performance varied across sub-volumes – mean Dice values of 0.85 (mandible basal), 0.82 (mandible alveolar), 0.78 (maxilla alveolar), 0.80 (upper central teeth), 0.69 (upper premolars), 0.76 (upper molars), 0.76 (lower central teeth), 0.70 (lower premolars), 0.71 (lower molars) – with limited applicability in segmenting sub-volumes absent in the data. The maxilla alveolar central sub-volume showed a statistically significant dose-volume difference in both D_mean and D_2%.</div></div><div><h3>Conclusions</h3><div>We present a novel DL-based auto-segmentation framework of orodental structures, enabling spatial localization of dose-related differences. This tool may enhance image-based bone injury detection and improve clinical decision-making in radiation oncology and dental care for head and neck cancer patients.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"35 ","pages":"Article 100817"},"PeriodicalIF":3.3,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144886033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-institution longitudinal apparent diffusion coefficient measurements in a diffusion weighted imaging phantom at room temperature","authors":"Chris Moore ,&nbsp;Charlotte Bull ,&nbsp;Angela Darekar ,&nbsp;Daniel Wilson ,&nbsp;Alex Goodall ,&nbsp;Prakash Manoharan ,&nbsp;Peter Hoskin ,&nbsp;Marcel van Herk ,&nbsp;David L. Buckley ,&nbsp;Damien J. McHugh ,&nbsp;Anubhav Datta ,&nbsp;Michael J. Dubec","doi":"10.1016/j.phro.2025.100814","DOIUrl":"10.1016/j.phro.2025.100814","url":null,"abstract":"<div><h3>Background and purpose</h3><div>This work contributes to technical validation of apparent diffusion coefficient (ADC) as a biomarker of cancer. The aim was to evaluate ADC accuracy, random error, short-term and long-term repeatability and reproducibility, across multiple institutions using a room temperature phantom.</div></div><div><h3>Materials and methods</h3><div>ADC measurements were made in a travelling room temperature diffusion weighted imaging (DWI) phantom on six scanners at four UK institutions over 18 months at six-month intervals. ADC bias measurements were calculated as the difference between measured and temperature corrected ground-truth ADC values and used to calculate mean ADC bias, isocentre ADC error estimate, short- and long-term intra-scanner repeatability as per the Quantitative Imaging Biomarkers Alliance (QIBA) DWI profiles, and inter-scanner reproducibility by calculating the 95 % limits of agreement for all ADC bias measurements.</div></div><div><h3>Results</h3><div>The use of a room-temperature phantom with a magnetic resonance (MR) readable thermometer enabled ADC measurements without ice-water setup, considerably simplifying logistics with respect to multi-institution ADC quality assurance. Mean ADC bias across all scanners and sessions was &lt;0.01 × 10⁻³ mm² s⁻¹ (0.81 %); mean isocentre ADC error estimate was 1.43 %; average scanner short-term repeatability was &lt;0.01 × 10⁻³ mm² s⁻¹ (1 %). Reproducibility was 0.07 × 10⁻³ mm² s⁻¹ (9 %).</div></div><div><h3>Conclusion</h3><div>Results indicated good ADC accuracy, repeatability and reproducibility; demonstrating the feasibility of transferring diagnostic DWI sequences between scanners from the same manufacturer, for use in multi-institution longitudinal studies, and assessing ADC with minimal quality control and harmonisation steps required.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"35 ","pages":"Article 100814"},"PeriodicalIF":3.4,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144711722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temporal drift in calibration of Ir-192 brachytherapy sources: A multi-center study on dosimetric discrepancies and metrological consistency","authors":"Javier Vijande ,&nbsp;Jacob G. Johansen ,&nbsp;Marisol De Brabandere ,&nbsp;Taran Paulsen Hellebust ,&nbsp;Antonio Herreros ,&nbsp;Christian Kirisits ,&nbsp;Ruud van Leeuwen ,&nbsp;Panagiotis Papagiannis ,&nbsp;Mark J. Rivard ,&nbsp;Frank-André Siebert ,&nbsp;Frank Verhaegen ,&nbsp;Jan Wiersma ,&nbsp;Åsa Carlsson Tedgren","doi":"10.1016/j.phro.2025.100801","DOIUrl":"10.1016/j.phro.2025.100801","url":null,"abstract":"<div><h3>Background and purpose</h3><div>High-dose-rate (HDR) brachytherapy relies on accurate and metrologically traceable source strength determination. Recent anecdotal reports and preliminary studies have suggested a possible temporal drift in the reference air kerma rate (<em>RAKR</em>) measured by clinical users compared to manufacturer certificates for ¹⁹²Ir sources. This study investigates the existence and magnitude of such drift across a large, multicenter European dataset and explores potential underlying causes.</div></div><div><h3>Materials and methods</h3><div>A total of over 1700 <em>RAKR</em> measurements for HDR and PDR brachytherapy sources, collected over two decades from 29 centers in 10 European countries, were analyzed. The ratio of hospital-measured <em>RAKR</em> to manufacturer-certified <em>RAKR</em> was assessed using linear regression and t-tests to evaluate drift. Data were corrected for center-dependent systematics and segmented around key dates corresponding to changes in primary standards. Supplementary analyses included leave-one-out testing and time-segmented trend assessment.</div></div><div><h3>Results</h3><div>A statistically significant drift (+0.15 %/year) was detected for all ¹⁹²Ir source types after 2018, correlating temporally with updates in the German Physikalisch-Technische Bundesanstalt (PTB) primary standards laboratory. Removing PTB corrections from manufacturer values nearly eliminated the observed drift. No such trend was observed for ⁶⁰Co sources.</div></div><div><h3>Conclusion</h3><div>The findings reveal a drift in hospital-to-manufacturer Ir-192 <em>RAKR</em> ratios that is temporally correlated with changes in metrology standards, not uniformly implemented across calibration chains. The true cause is however still unknown. The study aimed to investigate that greater transparency and harmonization among all stakeholders are essential to ensure dosimetric accuracy in HDR brachytherapy.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"35 ","pages":"Article 100801"},"PeriodicalIF":3.4,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144534823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional dose uncertainty maps based on the fraction of field edge dose for volumetric modulated arc therapy plans","authors":"Emmanouil Terzidis ,&nbsp;Fredrik Nordström ,&nbsp;Magnus Gustafsson ,&nbsp;Anna Karlsson ,&nbsp;Julia Götstedt ,&nbsp;Anna Bäck","doi":"10.1016/j.phro.2025.100802","DOIUrl":"10.1016/j.phro.2025.100802","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Absorbed dose uncertainties in radiotherapy plans are generally larger near field edges compared to the center of the field. The aim of this study was to investigate dose uncertainties related to the field edge in 3D for plans of varying complexities.</div></div><div><h3>Materials and methods</h3><div>A method was developed for calculation of the fraction of field edge dose (FED), that could be visualized as a 3D uncertainty map (3DUM_FED). Twelve clinical treatment plans were included for four different treatment sites that were reoptimized to create one plan with reduced complexity and one of increased complexity. 3DUM_FED was calculated for all 36 plans. The highest FED for a 2 cm³ volume (FED_{2 cm}³) and average FED (FED_mean) were calculated for the planning target volumes (PTV) and organs at risk (OAR) and compared with the edge area metric (EAM).</div></div><div><h3>Results</h3><div>High FED (above 20 %) were mainly found just outside the PTV border. FED_mean in PTV was highest for the plans of increased complexity. The FED_mean for PTVs and OARs, as well as the FED_{2 cm}³ for PTVs, correlated with ρ ≥ 0.81 to EAM. The FED_{2 cm}³ for OARs had a weaker correlation with EAM (ρ = 0.55). 3DUM_FED analysis revealed that plan complexity affects different parts of the patient volume in different ways.</div></div><div><h3>Conclusions</h3><div>3DUM_FED offers a way to estimate dose uncertainties related to the field edge in 3D. It also allows for separate evaluation in different regions of interest, unlike EAM, which mainly correlates with the dose uncertainty related to the PTV.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"35 ","pages":"Article 100802"},"PeriodicalIF":3.4,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144517364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time series analysis of dosimetric changes in target volumes and organs at risk monitored by cone beam computed tomography during radiotherapy for non-small-cell lung cancer","authors":"Chitchaya Suwanraksa ,&nbsp;Wathanya Sukcharoen ,&nbsp;Saranya Phuakphiuwong ,&nbsp;Sittinee Kooptisirirat ,&nbsp;Kantida Krutsuwan ,&nbsp;Chanakran Nantasri ,&nbsp;Apisit Jakkrit ,&nbsp;Thanarpan Peerawong ,&nbsp;Ponlagrit Kumwichar","doi":"10.1016/j.phro.2025.100822","DOIUrl":"10.1016/j.phro.2025.100822","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Technological advancements in radiotherapy have enhanced the ability to increase tumor doses while sparing normal tissues. We performed a time-series cluster analysis to characterize dynamic variations in dosimetry during radiotherapy.</div></div><div><h3>Materials and Methods</h3><div>We analyzed dosimetric variations of 40 patients with non-small-cell lung cancer who received 60 Gy over 30 daily cone beam computed tomography-guided fractions. Percentage deviations from planned doses across all fractions were calculated for organs at risk (OARs) (lungs, heart, spinal cord, and esophagus), gross tumor volume, clinical target volume (CTV), and planning target volume. K-means clustering with dynamic time-warping distances was applied to identify temporal dose patterns. The target volume with the lowest variance (95 % dose coverage of the CTV [CTV_D95]) was selected as a reference. OAR dose deviations were clustered using the elbow method. Mean temporal trends were plotted with 95 % confidence intervals.</div></div><div><h3>Results</h3><div>The CTV_D95 remained stable across all fractions and all patients and was used as a reference for time-series clustering. Cluster 1 included the majority of patients and exhibited low variability and predictable dose trajectories with gradual increases in the lung and esophagus doses and stable patterns in the heart and spinal cord. Cluster 2 showed high inter-fractional variability with progressively increasing OAR dose deviations.</div></div><div><h3>Conclusions</h3><div>Time-series clustering enabled early identification of patients with distinct dose evolution patterns. The stable trajectories of Cluster 1 may serve as internal references for adaptive radiotherapy. Variability in Cluster 2 underscores the need for routine dose monitoring to support timely offline adaptation.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"35 ","pages":"Article 100822"},"PeriodicalIF":3.3,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144827666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dosimetric feasibility of stereotactic arrhythmia radioablation for ventricular tachycardia in patients with a subcutaneous implantable cardioverter defibrillator","authors":"Lena Kaestner ,&nbsp;Jingyang Xie ,&nbsp;Hannah Fanslau ,&nbsp;Kerstin Siebenlist ,&nbsp;Miriam Eckl ,&nbsp;Hans Oppitz ,&nbsp;Jens Fleckenstein ,&nbsp;Daniel Buergy ,&nbsp;Mustafa Kuru ,&nbsp;Jürgen Kuschyk ,&nbsp;Daniel Dürschmied ,&nbsp;Mathieu Kruska ,&nbsp;David Krug ,&nbsp;Frank A. Giordano ,&nbsp;Achim Schweikard ,&nbsp;Oliver Blanck ,&nbsp;Boris Rudic ,&nbsp;Judit Boda-Heggemann","doi":"10.1016/j.phro.2025.100827","DOIUrl":"10.1016/j.phro.2025.100827","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Subcutaneous implantable cardioverter defibrillators (S-ICDs) are increasingly used to prevent sudden cardiac death. Due to their placement near the left lateral and apical myocardium, S-ICDs can present technical challenges for stereotactic arrhythmia radioablation (STAR) of ventricular tachycardia. This study aimed to evaluate the feasibility of STAR in patients with S-ICDs.</div></div><div><h3>Materials and methods</h3><div>Previously acquired cardiac computed tomography data from ten S-ICD patients were retrospectively analyzed. Organs at risk, S-ICD components, and hypothetical planning target volumes (PTV) for segments 8 (septal), 11 (lateral), and 17 (apical) were contoured. For each patient and segment, two treatment plans were calculated with a prescribed PTV dose of 25 Gy: one plan sparing the S-ICD from the primary radiotherapy beam (‘spared’) and one without this constraint (‘non-spared’).</div></div><div><h3>Results</h3><div>The S-ICD was successfully spared from the primary beam in 27 out of 30 plans, with <em>D</em>_0.035cm³ &lt; 1 Gy. In three spared plans (PTV segment 11) with a distance between PTV and S-ICD &lt;4 cm, <em>D</em>_0.035cm³ exceeded 1 Gy. Spared plans for PTV segment 11 showed significant higher dose/volume metrics and reduced plan quality compared to non-spared plans (p &lt; 0.05), although 9/10 plans remained clinically acceptable. For PTV segment 8 and segment 17, no clinical or statistical differences were observed.</div></div><div><h3>Conclusions</h3><div>The presence of an S-ICD is not a contraindication for STAR, although plan quality may decrease with PTVs in lateral segments. Rare cases with a distance between PTV and S-ICD &lt;4 cm may complicate radiation treatment planning.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"35 ","pages":"Article 100827"},"PeriodicalIF":3.3,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144895306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of online adaptation strategies for magnetic resonance guided prostate radiation therapy","authors":"Iymad R. Mansour ,&nbsp;Chris D. Johnstone ,&nbsp;Victor Malkov ,&nbsp;Daniel Létourneau ,&nbsp;Peter Chung ,&nbsp;Tony Tadic ,&nbsp;Jeff D. Winter","doi":"10.1016/j.phro.2025.100816","DOIUrl":"10.1016/j.phro.2025.100816","url":null,"abstract":"<div><h3>Background and purpose</h3><div>MR-guided adaptive radiation therapy allows for daily plan adaptation to account for anatomical changes. Two common strategies are adapt-to-position (ATP), involving re-optimization based on isocenter shifts, and adapt-to-shape (ATS), involving full recontouring and reoptimization. This study provides a dosimetric comparison of ATP and ATS using accumulated dose.</div></div><div><h3>Materials and methods</h3><div>Dose accumulation was performed for 35 patients with prostate cancer treated on a 1.5 T MR-Linac. All patients received ATS-based treatment with either 30.0 Gy in 5 fractions (30.0/5) or 42.7 Gy in 7 fractions (42.7/7), using a 5 mm isotropic PTV margin. ATP plans were retrospectively simulated. For each fraction, dose was mapped to a reference image using deformable image registration and summed across fractions. Fractional and accumulated dose-volume histogram (DVH) metrics were compared between ATS and ATP and correlated with daily anatomical variation.</div></div><div><h3>Results</h3><div>ATP and ATS achieved equivalent accumulated CTV D95 and D98 for both regimens. In the 30.0/5 cohort, small but statistically significant differences in OAR dose were observed: accumulated bladder D40 was 4 % lower for ATP (1.27 Gy; p = 0.0004), and rectum D50 was 1 % lower for ATP (0.40 Gy; p = 0.0008). Differences in rectum D1cc and bladder D5cc were not significant. In the 42.7/7 cohort, femur D5 was 3 % higher for ATP (0.83 Gy; p = 0.02); other differences were insignificant. Dosimetric differences across strategies correlated with interfraction motion.</div></div><div><h3>Conclusion</h3><div>ATP and ATS provided equivalent target coverage. OAR differences were statistically significant in some cases but remained within clinical tolerances, suggesting minimal clinical impact.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"35 ","pages":"Article 100816"},"PeriodicalIF":3.3,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144827667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of proton and photon therapy in stereotactic arrhythmia radioablation for ventricular tachycardia","authors":"Keyur D. Shah ,&nbsp;Chih-Wei Chang ,&nbsp;Pretesh Patel ,&nbsp;Sibo Tian ,&nbsp;Yuan Shao ,&nbsp;Kristin A Higgins ,&nbsp;Yinan Wang ,&nbsp;Justin Roper ,&nbsp;Jun Zhou ,&nbsp;Zhen Tian ,&nbsp;Xiaofeng Yang","doi":"10.1016/j.phro.2025.100807","DOIUrl":"10.1016/j.phro.2025.100807","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Ventricular tachycardia (VT) is a life-threatening arrhythmia commonly treated with catheter ablation; however, some cases remain refractory. Stereotactic arrhythmia radioablation (STAR) offers a non-invasive alternative. While photon-based STAR is effective, proton therapy may improve dose conformity and spare critical organs at risk (OARs), including the heart itself. The aim of this study was to compare the dose-volume metrics between proton and photon therapy for VT.</div></div><div><h3>Materials and Methods</h3><div>We retrospectively analyzed 34 VT patients who received photon STAR. Proton STAR plans were generated using robust optimization in a commercial treatment planning system to deliver the same prescription dose of 25 Gy in a single fraction. Dose-volume metrics, including <em>D₉₉</em>, <em>D₉₅</em>, <em>D_mean</em>, and <span><math><mrow><msub><mi>D</mi><msup><mrow><mn>0.03</mn><mi>c</mi><mi>m</mi></mrow><mn>3</mn></msup></msub></mrow></math></span>, were extracted for critical OARs (heart, lungs, cardiac-chambers) and target. Shapiro-Wilk tests were used to assess normality, with paired t-tests or Wilcoxon signed-rank tests for statistical comparisons between modalities, with Bonferroni correction applied for multiple comparisons.</div></div><div><h3>Results</h3><div>Proton and photon plans achieved comparable target coverage, with CTV <em>D₉₅</em> of 25.8 [21.6–28.7] Gy(RBE) vs. 27.2 [21.6–29.3] Gy (p &lt; 0.001). Proton therapy significantly reduced OAR doses, including heart <em>D_mean</em> (3.6 ± 1.5 Gy(RBE) vs. 5.5 ± 2.0 Gy, p &lt; 0.001) and lungs <em>D_mean</em> (0.6 [0.0–1.9] Gy(RBE) vs. 1.2 [0.2–2.6] Gy, p &lt; 0.001), while maintaining optimal target coverage.</div></div><div><h3>Conclusion</h3><div>Proton therapy for STAR demonstrated significant potential for OARs sparing compared to photon therapy for VT, while maintaining equivalent target coverage. These findings highlight the potential of proton therapy to improve outcomes for VT patients.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"35 ","pages":"Article 100807"},"PeriodicalIF":3.4,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144588456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}