Physics and Imaging in Radiation Oncology最新文献

{"title":"Benchmarking a new radiochromic film type for photon and proton beam dosimetry","authors":"Peter Kuess ,&nbsp;Barbara Knäusl ,&nbsp;Sarah Helletzgruber ,&nbsp;Dietmar Georg ,&nbsp;Hugo Palmans ,&nbsp;Wolfgang Lechner","doi":"10.1016/j.phro.2026.100985","DOIUrl":"10.1016/j.phro.2026.100985","url":null,"abstract":"<div><h3>Background and Purpose:</h3><div>EBT4 Radiochromic films (RCFs) are replacing the well-described EBT3 type. This study aimed to benchmark the EBT4 type against its predecessor for photon (kV and MV) and proton beam dosimetry.</div></div><div><h3>Materials and Methods:</h3><div>Differences between the film types regarding the signal-to-noise ratio (SNR) were investigated in 6<!--> <!-->MV photon and 148.2<!--> <!-->MeV proton beams in the dose range of 0.2<!--> <!-->Gy to 10<!--> <!-->Gy for all RGB channels. The effect of the dose-averaged linear energy transfer (LET<span><math><msub><mrow></mrow><mrow><mi>d</mi></mrow></msub></math></span>) on the response of both film types was compared within a proton spread-out Bragg peak (SOBP). Furthermore, the relative response in low-kV X-rays was studied and the effect of long-term storage on both film types.</div></div><div><h3>Results:</h3><div>The SNR of EBT4 films was statistically superior for MV-photon irradiations above 1.5<!--> <!-->Gy in the red channel by up to 29<!--> <!-->%. For low-dose proton irradiations, the SNR of EBT3 was higher. The underresponse of both film types in a proton SOBP reached 5 to 7<!--> <!-->%. In low kV X-ray beams, EBT4 deviated from EBT3 on average by 2.5<!--> <!-->%. For irradiations of films with a dose of 2<!--> <!-->Gy or less after 216 days of storage, smaller differences in terms of pixel values were observed for films placed at 10°C.</div></div><div><h3>Conclusions:</h3><div>The presented results are in accordance with recent studies on EBT4 films and extend the knowledge on this film type, especially regarding proton beams and film storage.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"39 ","pages":"Article 100985"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147860611","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":"Deep learning for dose-averaged linear energy transfer estimation in pencil-beam scanning and double scattering proton radiotherapy plans with uncertainty-aware external validation","authors":"Aaron Kieslich ,&nbsp;Yerik Singh ,&nbsp;Martina Palkowitsch ,&nbsp;Sebastian Starke ,&nbsp;Fabian Hennings ,&nbsp;Esther G.C. Troost ,&nbsp;Mechthild Krause ,&nbsp;Jona Bensberg ,&nbsp;Armin Lühr ,&nbsp;Feline Heinzelmann ,&nbsp;Christian Bäumer ,&nbsp;Beate Timmermann ,&nbsp;Nicolas Depauw ,&nbsp;Helen A. Shih ,&nbsp;Steffen Löck","doi":"10.1016/j.phro.2026.100998","DOIUrl":"10.1016/j.phro.2026.100998","url":null,"abstract":"<div><h3>Background and Purpose:</h3><div>Accounting for the linear energy transfer (LET) in proton radiotherapy may reduce treatment-related side effects. When Monte Carlo (MC) simulations are unavailable, deep-learning (DL) surrogate models can be applied. We develop DL LET models for brain tumour patients and assess their uncertainty for an external dataset lacking LET reference.</div></div><div><h3>Material and Methods:</h3><div>A multi-institutional dataset of 570 patients with 605 treatment plans was used for model development and evaluation. DL models predicting dose-averaged LET (LET<span><math><msub><mrow></mrow><mrow><mi>d</mi></mrow></msub></math></span>) were trained separately for pencil-beam scanning (PBS) and double scattering (DS) treatments, as well as a combined PBS+DS model. Deviations from MC reference were evaluated by median and 98th percentile voxelwise absolute errors (VAE) in organs at risk and the treatment target. Uncertainty was evaluated via deep ensemble variance and latent space distance, correlated with the median VAE, and applied to an external DS cohort without LET<span><math><msub><mrow></mrow><mrow><mi>d</mi></mrow></msub></math></span> reference.</div></div><div><h3>Results:</h3><div>The PBS+DS model achieved average median VAEs below 0.42 keV/<span><math><mi>μ</mi></math></span>m. Ensemble variance and latent space distance showed positive correlations with error, with the strongest association observed for ensemble variance (up to <span><math><mi>ρ</mi></math></span> <span><math><mo>=</mo></math></span> 0.88). Both uncertainty metrics indicated an estimated average median VAE below 0.54 keV/<span><math><mi>μ</mi></math></span>m for the DS model on the external DS data.</div></div><div><h3>Conclusion:</h3><div>DL models accurately approximate LET<span><math><msub><mrow></mrow><mrow><mi>d</mi></mrow></msub></math></span> for PBS and DS proton radiotherapy. Uncertainty estimation provides indirect evidence of model reliability and enables performance estimation in cohorts lacking LET<span><math><msub><mrow></mrow><mrow><mi>d</mi></mrow></msub></math></span> reference, supporting safer application in retrospective analyses and clinical research.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"39 ","pages":"Article 100998"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147996456","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":"Transformer-based cardiac substructure segmentation from contrast and non-contrast computed tomography for radiotherapy planning","authors":"Aneesh Rangnekar ,&nbsp;Nikhil Mankuzhy ,&nbsp;Jonas Willmann ,&nbsp;Chloe Min Seo Choi ,&nbsp;Abraham Wu ,&nbsp;Maria Thor ,&nbsp;Andreas Rimner ,&nbsp;Harini Veeraraghavan","doi":"10.1016/j.phro.2026.101011","DOIUrl":"10.1016/j.phro.2026.101011","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Accurate segmentation of cardiac substructures on computed tomography (CT) scans is essential for radiotherapy planning. This study evaluated whether pretrained transformers enabled data-efficient training using a fixed architecture with balanced curriculum learning while achieving robust generalization to imaging and patient variations.</div></div><div><h3>Materials and Methods</h3><div>A hybrid pretrained transformer-convolutional network, self-distilled masked image transformer (SMIT), was fine-tuned using lung cancer patient scans (Cohort I, training N = 180) and tested on held-out Cohort I lung cancer scans (testing N = 60) and breast cancer scans (Cohort II, N = 65). Two configurations were evaluated: SMIT-Balanced (32 contrast-enhanced CTs, 32 non-contrast CTs) and SMIT-Oracle (180 CTs). Performance was compared with nnU-Net and TotalSegmentator. Segmentation accuracy was assessed primarily using the 95th percentile Hausdorff distance (HD95), along with radiation dose and overlap-based metrics as secondary endpoints.</div></div><div><h3>Results</h3><div>SMIT-Balanced approached SMIT-Oracle performance despite using 64% fewer training scans, with mean HD95 of 6.6 versus 5.4 mm in Cohort I and 10.0 versus 9.4 mm in Cohort II. On the Cohort I held-out test set, SMIT-Balanced mean HD95 was within 1.0 mm of nnU-Net. Cross-cohort testing showed larger accuracy degradation with nnU-Net than SMIT-Balanced (62% versus 50%, absolute change 4.5 mm versus 3.4 mm). Dose metrics derived from SMIT-Balanced were equivalent to manual delineations.</div></div><div><h3>Conclusions</h3><div>Balanced curriculum training reduced labeled data requirements within the SMIT architecture. SMIT-Balanced was comparable to nnU-Net on Cohort I held-out data and showed smaller cross-cohort HD95 degradation.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"39 ","pages":"Article 101011"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148185136","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":"Trade-offs in proton and photon radiotherapy for pituitary adenomas","authors":"David J.A. Palm ,&nbsp;John Paulissen ,&nbsp;Rik Emmah ,&nbsp;David Hofstede ,&nbsp;Nikolina E. Birimac ,&nbsp;Ruud Houben ,&nbsp;Marlies E. Granzier ,&nbsp;Marloes Nogarede ,&nbsp;Ans C.C. Swinnen ,&nbsp;Jasper van Aalst ,&nbsp;Yasin Temel ,&nbsp;Marleen Kars ,&nbsp;Daniëlle B.P. Eekers ,&nbsp;Catharina M.L. Zegers ,&nbsp;Inge Compter","doi":"10.1016/j.phro.2026.100994","DOIUrl":"10.1016/j.phro.2026.100994","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Pituitary Adenomas (PAs) are tumours proximal to sensitive organs of interest (OOIs). These tumours may be well-suited for proton therapy due to the Bragg peak. Few studies have evaluated the potential dose-volume benefits of protons for PAs in the pencil beam scanning era.</div></div><div><h3>Materials and Methods</h3><div>Treatment plans for 15 PA patients were made using intensity modulated proton therapy (IMPT), coplanar- and- non-coplanar photon therapy. Dose distributions to OOIs were compared using the Radiation Oncology Collaborative Comparison Group’s (ROCOCO) Performance Scoring System (RPSS), which estimates adverse event (AE) burden.</div></div><div><h3>Results</h3><div>Proton therapy resulted in significantly lower overall estimated AE burden than both photon modalities (median RPSS: 1.09 vs. 1.24; p &lt; 0.005). This reduction was due to significantly lower D_40% to the hippocampi. For the right hippocampus, median D_40% (EQD_Gy2) was 1.1<!--> <!-->Gy with IMPT, compared with 4.9<!--> <!-->Gy for coplanar and 3.2<!--> <!-->Gy for non-coplanar photons. Doses with protons and non-coplanar photons were significantly lower than those for coplanar photons (p &lt; 0.001). For the left hippocampus, IMPT achieved a median D_40% of 0.7<!--> <!-->Gy, compared with 5.0<!--> <!-->Gy for coplanar and 2.7<!--> <!-->Gy for non-coplanar photons. Non-coplanar was significantly lower than coplanar (p &lt; 0.001), while IMPT was significantly lower than both photon modalities (p &lt; 0.001). Protons delivered higher doses to the brainstem, optic nerves, chiasm, and the hypothalami.</div></div><div><h3>Conclusions</h3><div>These findings indicate that IMPT can significantly reduce AEs to critical brain structures. Although considerations of cost, accessibility, and clinical validation remain, IMPT may offer a meaningful therapeutic advantage.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"39 ","pages":"Article 100994"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147952764","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":"Feasibility of longitudinal relaxation rate mapping with non-Cartesian sampling and compressed sensing on a 1.5 T magnetic resonance linear accelerator","authors":"Lucas McCullum ,&nbsp;Michael J. van Rijssel ,&nbsp;Ken-Pin Hwang ,&nbsp;Yao Ding ,&nbsp;Chad Tang ,&nbsp;Comron Hassanzadeh ,&nbsp;Jinzhong Yang ,&nbsp;Peter A. Balter ,&nbsp;Jihong Wang ,&nbsp;Clifton D. Fuller ,&nbsp;Ergys D. Subashi","doi":"10.1016/j.phro.2026.101002","DOIUrl":"10.1016/j.phro.2026.101002","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Quantitative T1 mapping is a major building block in several multiparametric magnetic resonance imaging (MRI) protocols intended for adaptive radiation therapy. The implementation of these protocols is challenging in anatomical sites that experience large physiological motion. The purpose of this study was to implement and validate motion-resolved quantitative T1 mapping on a 1.5 T MRI linear accelerator (MR-Linac) combining non-Cartesian k-space sampling trajectories with compressed sensing (CS) reconstruction.</div></div><div><h3>Materials and methods</h3><div>Four 3-dimensional non-Cartesian k-space trajectories were evaluated: kooshball and stack-of-stars sampling using half- and full-spoke coverage. A variable flip angle acquisition was performed using the spoiled gradient-echo sequence. Gradient delay timing was optimized to minimize trajectory-induced artifacts. Eight CS reconstruction strategies were tested using spatial/spatiotemporal regularization operators. Reconstructions were evaluated and sorted by spatial resolution, bias, and variability. Motion-resolved T1 mapping was validated using two standard phantoms, one healthy volunteer, and one kidney cancer patient using respiratory self-gating and phase-sorted reconstruction.</div></div><div><h3>Results</h3><div>All non-Cartesian T1 maps demonstrated high repeatability and low longitudinal bias in phantom studies, with coefficients of variation below 3.3%. Spatiotemporal regularization preserved spatial resolution and quantitative accuracy at undersampling factors up to 20-fold. In human subjects, non-Cartesian T1 mapping provided improved accuracy and reduced variability in mobile abdominal tissues compared to Cartesian acquisitions.</div></div><div><h3>Conclusions</h3><div>Quantitative T1 mapping using non-Cartesian trajectories and CS reconstruction is feasible on a 1.5 T MR-Linac. The proposed approach enables accurate motion-resolved quantitative imaging within clinically practical acquisition times, establishing a foundation for multiparametric MRI in adaptive radiotherapy.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"39 ","pages":"Article 101002"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147992494","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":"Segmentation regularized training for multi-domain deep learning registration applied to magnetic resonance-guided prostate cancer radiotherapy","authors":"Sudharsan Madhavan ,&nbsp;Chengcheng Gui ,&nbsp;Lando Bosma ,&nbsp;Josiah Simeth ,&nbsp;Jue Jiang ,&nbsp;Nicolas Côté ,&nbsp;Nima Hassan Rezaeian ,&nbsp;Himanshu Nagar ,&nbsp;Victoria Brennan ,&nbsp;Neelam Tyagi ,&nbsp;Harini Veeraraghavan","doi":"10.1016/j.phro.2026.100989","DOIUrl":"10.1016/j.phro.2026.100989","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Accurate deformable image registration (DIR) is required for contour propagation and dose accumulation for magnetic resonance guided adaptive radiotherapy (MRgART). The goal of this study was to train segmentation regularized deep learning (DL) DIR and assess domain invariant MR-MR registration.</div></div><div><h3>Materials and methods</h3><div>DL-DIR based progressively refined registration and segmentation (ProRSeg) and VoxelMorph were trained with and without organ weighted segmentation regularization with 262 MR pairs from same domain dataset of longitudinal 3 Tesla MR simulation (MR-Sim) scans of patients with prostate cancer acquired before and every 3 months following radiotherapy. Models were compared against variational DIR by measuring accuracy of organs and clinical target volume (CTV) contour propagation accuracy on same- (58 pairs), cross- (72 1.5 Tesla MR-Linac pairs from consecutive daily treatment fractions), and mixed-domain (42 MRSim planning − MR-Linac first fraction pairs) datasets. Dose accumulation was performed for 42 patients undergoing 5-fraction MRgART on MR-Linac.</div></div><div><h3>Results</h3><div>ProRSeg produced robust DIR on cross- (all organs) and mixed-domain (bladder, CTV) datasets. It was the most accurate method for highly deforming organs including bladder and rectum. Segmentation regularization enhanced accuracy of both ProRSeg and VoxelMorph compared to unregularized versions. Dose accumulation feasibility study with ProRSeg indicated that 83.3% of patients met key institutional constraints for CTV coverage and bladder sparing.</div></div><div><h3>Conclusions</h3><div>ProRSeg was a feasible approach for multi-domain MR-MR registration for prostate cancer patients. Dose accumulation analysis indicated preliminary feasibility to evaluate compliance of delivered treatments to clinical constraints.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"39 ","pages":"Article 100989"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147996540","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":"Structure visibility and online adaptation suitability of a new high-performance ring-gantry cone-beam computed tomography imaging system in thoracic radiotherapy","authors":"Agustinus J.A.J. van de Schoot,&nbsp;Joan J. Penninkhof,&nbsp;Britt Kunnen,&nbsp;Kimm P. Fremeijer,&nbsp;Elise M. Nicolai – Koornneef,&nbsp;Kirsten Offereins - van Harten,&nbsp;Judith H. Sluijter,&nbsp;Nienke D. Sijtsema,&nbsp;Marjan van de Pol,&nbsp;Raymond de Boer,&nbsp;Maarten L.P. Dirkx,&nbsp;Steven F. Petit","doi":"10.1016/j.phro.2026.100984","DOIUrl":"10.1016/j.phro.2026.100984","url":null,"abstract":"<div><h3>Background and purpose</h3><div>A recently introduced high-performance ring-gantry cone-beam computed tomography (CBCT_H) imaging system promises superior image quality compared with conventional ring-gantry CBCT imaging (CBCT_C), however, it incurs additional costs. Our aim was to determine the added value of CBCT_H compared with CBCT_C in thoracic radiotherapy by quantifying structure visibility and online adaptive radiotherapy (oART) suitability.</div></div><div><h3>Materials and methods</h3><div>Twenty lung cancer patients treated in free-breathing and twenty left-sided breast cancer patients treated in deep-inspiration breath-hold were included in this prospective clinical study. Three CBCT imaging pairs per patient, consisting of CBCT_H and CBCT_C acquired on consecutive days, were included. Four observers independently scored all 240 CBCT datasets on structure visibility and oART suitability (1–5 scale). The effect of respiratory motion management on image quality enhancement was determined by comparing cohort-specific score differences.</div></div><div><h3>Results</h3><div>In total, 4440 structure visibility and 960 oART suitability scores were collected. Patient-averaged scores favored CBCT_H in 82% (100%) of the cases in the lung (breast) cohort. Compared with CBCT_C, CBCT_H-based scores increased significantly (p &lt; 0.05) in both cohorts for structure visibility (lung: 2.8 to 3.1; breast: 3.1 to 3.8) and oART suitability (lung: 2.6 to 2.9; breast: 3.1 to 3.9). Structure visibility (oART suitability) score differences increased with deep-inspiration breath-hold (p &lt; 0.001) compared with free-breathing, by on average 0.38 (0.39).</div></div><div><h3>Conclusion</h3><div>In thoracic radiotherapy, CBCT_H yielded statistically significant improvements in structure visibility and oART suitability where the largest improvements were obtained for CBCT_H in deep-inspiration breath-hold. These results can contribute to informed decision-making regarding cost-effectiveness of CBCT_H.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"39 ","pages":"Article 100984"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147805730","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":"Corrigendum to “Clinical target volumes for glioma – Automated delineation to improve neuroanatomic consistency” [Phys. Imaging Radiat. Oncol. 36 (2025) 100865]","authors":"Gregory Buti ,&nbsp;Marcela Giovenco ,&nbsp;Tugba Yilmaz ,&nbsp;Ali Ajdari ,&nbsp;Christopher P. Bridge ,&nbsp;Gregory C. Sharp ,&nbsp;Fredrik Löfman ,&nbsp;Helen A. Shih ,&nbsp;Thomas Bortfeld","doi":"10.1016/j.phro.2026.100975","DOIUrl":"10.1016/j.phro.2026.100975","url":null,"abstract":"","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"39 ","pages":"Article 100975"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147805791","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":"Robust framework for adaptive field-of-view automatic segmentation in vaginal brachytherapy for endometrial cancer","authors":"Adrià Casamitjana ,&nbsp;Ana María Gómez Fresco ,&nbsp;Cristian Candela-Juan ,&nbsp;Raúl Tudela ,&nbsp;Roser Sala-Llonch ,&nbsp;Sara Moreno López ,&nbsp;Faegheh Noorian ,&nbsp;Angeles Rovirosa ,&nbsp;Aida Niñerola-Baizán ,&nbsp;Antonio Herreros","doi":"10.1016/j.phro.2026.101000","DOIUrl":"10.1016/j.phro.2026.101000","url":null,"abstract":"<div><h3>Background and purpose</h3><div>The lack of robust automatic tools for segmentation in vaginal brachytherapy (VBT) limits efficiency and reproducibility in clinical practice. We aimed to develop a framework for automatic segmentation of the clinical target volume (CTV) and organs of interest (OOIs) for endometrial cancer patients that undergo vaginal cuff brachytherapy.</div></div><div><h3>Material and methods</h3><div>We developed a three-step framework based on nnUNet and adapted to our context to segment the CTV/OOIs on pre-treatment computed tomography (CT) scans. Our method was adaptive to different contouring protocols used in clinical practice, where images were partly labelled, by either providing labels within a region of interest and/or considering only a subset of present structures. A dataset of 289 patients treated between 2014 and 2021 was used for model development (139/35/115 for training, validation and testing).</div></div><div><h3>Results</h3><div>The Dice similarity coefficient of the CTV was 87.7%, while OOI Dice coefficients were 72.6%, 88.9%, 86.3% for the small bowel, bladder and rectum, respectively. The average absolute D_2cm3 deviations were 27.5(±58.7), 25.5(±21.0), and 21(±19.1) cGy for the small bowel, bladder and rectum, respectively. The average absolute D₉₀_% deviation was 17.0(±19.6) cGy. Clinical transferability was assessed using a 1–4 scale, achieving a median of 4 for the CTV, 3 for bladder and rectum, and 2 for the small bowel.</div></div><div><h3>Conclusions</h3><div>Our method segmented the CTV and OOIs from CT scans with high quality and reliable dose calculations within the relevant range. Our framework outperformed state-of-the-art methods and potentially could help reduce complexity and time in VBT protocols.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"39 ","pages":"Article 101000"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147996538","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":"Improved organs-of-interest dose reduction potential with intensity modulated proton therapy and breath-hold in mediastinal lymphoma","authors":"Bastiaan D.P. Ta ,&nbsp;Richard A.M. Canters ,&nbsp;Kim van der Klugt ,&nbsp;Gloria Vilches-Freixas ,&nbsp;Esther Kneepkens ,&nbsp;Fleur Vereijken ,&nbsp;Maud Cobben ,&nbsp;Maud van den Bosch ,&nbsp;Indra Lubken ,&nbsp;Cissy Stultiens ,&nbsp;Marije Velders ,&nbsp;Tina Verstappen ,&nbsp;Gyanne Tholen ,&nbsp;Anne G.H. Niezink ,&nbsp;Dirk K.M. De Ruysscher ,&nbsp;Maaike Berbée","doi":"10.1016/j.phro.2026.100996","DOIUrl":"10.1016/j.phro.2026.100996","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>For mediastinal lymphoma patients, comparative data on intensity modulated proton therapy in breath-hold (IMPT-BH) versus other radiation techniques remain limited, particularly regarding dose-volume histogram (DVH) metrics and normal tissue complication probability (NTCP) for late side effects.</div></div><div><h3>Materials and Methods</h3><div>This retrospective in silico planning study included 58 lymphoma patients, treated between 2019 and May 2024, having 4D-CT and BH-CT available. Four plans per patient were made: volumetric arc therapy in free-breathing (VMAT-FB), VMAT-BH, IMPT-FB, and IMPT-BH. An absolute dose difference ≥ 1 Gy was considered clinically relevant, and patients were assigned to the optimal technique.</div></div><div><h3>Results</h3><div>IMPT-BH resulted in the lowest average mean heart dose (MHD) at 5.4 Gy (<em>p</em> &lt; 0.01) compared to VMAT-FB (8.0 Gy), VMAT-BH (6.3 Gy) and IMPT-FB (5.8 Gy). IMPT-BH resulted in the lowest average mean lung dose (MLD) at 6.7 Gy (<em>p</em>&lt;0.01), compared to VMAT-FB (9.2 Gy), VMAT-BH (7.5 Gy), and IMPT-FB (7.3 Gy). Average bilateral mean breast dose (MBD) was lower with IMPT (2.1 Gy) compared to VMAT (3.2 Gy; <em>p</em>&lt;0.01). IMPT was optimal for ≥ 69% of patients.</div></div><div><h3>Conclusions</h3><div>IMPT-BH achieved the lowest MHD, MLD, and bilateral MBD compared to IMPT-FB, VMAT-BH, and VMAT-FB in the majority of patients.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"39 ","pages":"Article 100996"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147952761","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}