Pub Date : 2026-03-01Epub Date: 2026-03-15DOI: 10.1016/j.phro.2026.100948
Anna-Maria Shiarli , Michael J. Dubec , Merina Ahmed , Jon T. Asmussen , Hannah Bainbridge , José S. Belderbos , Sean Brown , Johan Bussink , David Cobben , Bram H.J. Geurts , Andrew Hope , John Kavanagh , Dow-Mu Koh , Ferry Lalezari , Alexander V. Louie , Laura G. Merckel , Firdaus A.M. Hoesein , James P.B. O’Connor , Rocio Perez-Johnston , Tyson J. Reeve , Fiona McDonald
Background and purpose
The use of Magnetic Resonance imaging (MRI) for radiotherapy planning and guidance for locally advanced non-small cell lung cancer (LA NSCLC) is novel. The superior soft tissue definition of MRI compared to CT, may facilitate more accurate gross tumour volume (GTV) definition, with the goal of improving radiotherapy precision. This work aims to develop GTV contouring recommendations for NSCLC on MRI.
Materials and methods
Two international training workshops on GTV delineation for LA NSCLC were attended by thoracic radiation oncologists and MR radiologists. Thoracic radiation oncology experts contoured nine cases of LA NSCLC, firstly, on mid-position 4D-CT with PET-CT guidance, and secondly on non-contrast MRI, registered with the CT and PET-CT. Consensus contours generated on CT and MRI were discussed and finalised during two international meetings.
Results
Recommendations on GTV delineation for LA NSCLC for both the primary tumour and individual lymph node stations using thoracic MRI were produced and are provided in this document. Consensus contours generated on CT and MRI for specific clinical scenarios were demonstrated and challenges addressed.
Conclusions
We provide the first set of consensus recommendations on GTV contouring on MRI for LA NSCLC through an international collaborative process between international experts in thoracic radiation oncology and MR radiology. This work provides an initial step towards standardisation of lung GTV delineation on MRI, which is necessary prior to any meaningful assessment of the benefits of MRI in GTV definition compared to current practice.
{"title":"Recommendations for contouring of gross tumour volume for locally advanced lung cancer using magnetic resonance imaging","authors":"Anna-Maria Shiarli , Michael J. Dubec , Merina Ahmed , Jon T. Asmussen , Hannah Bainbridge , José S. Belderbos , Sean Brown , Johan Bussink , David Cobben , Bram H.J. Geurts , Andrew Hope , John Kavanagh , Dow-Mu Koh , Ferry Lalezari , Alexander V. Louie , Laura G. Merckel , Firdaus A.M. Hoesein , James P.B. O’Connor , Rocio Perez-Johnston , Tyson J. Reeve , Fiona McDonald","doi":"10.1016/j.phro.2026.100948","DOIUrl":"10.1016/j.phro.2026.100948","url":null,"abstract":"<div><h3>Background and purpose</h3><div>The use of Magnetic Resonance imaging (MRI) for radiotherapy planning and guidance for locally advanced non-small cell lung cancer (LA NSCLC) is novel. The superior soft tissue definition of MRI compared to CT, may facilitate more accurate gross tumour volume (GTV) definition, with the goal of improving radiotherapy precision. This work aims to develop GTV contouring recommendations for NSCLC on MRI.</div></div><div><h3>Materials and methods</h3><div>Two international training workshops on GTV delineation for LA NSCLC were attended by thoracic radiation oncologists and MR radiologists. Thoracic radiation oncology experts contoured nine cases of LA NSCLC, firstly, on mid-position 4D-CT with PET-CT guidance, and secondly on non-contrast MRI, registered with the CT and PET-CT. Consensus contours generated on CT and MRI were discussed and finalised during two international meetings.</div></div><div><h3>Results</h3><div>Recommendations on GTV delineation for LA NSCLC for both the primary tumour and individual lymph node stations using thoracic MRI were produced and are provided in this document. Consensus contours generated on CT and MRI for specific clinical scenarios were demonstrated and challenges addressed.</div></div><div><h3>Conclusions</h3><div>We provide the first set of consensus recommendations on GTV contouring on MRI for LA NSCLC through an international collaborative process between international experts in thoracic radiation oncology and MR radiology. This work provides an initial step towards standardisation of lung GTV delineation on MRI, which is necessary prior to any meaningful assessment of the benefits of MRI in GTV definition compared to current practice.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"38 ","pages":"Article 100948"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147541348","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}
Pub Date : 2026-03-01Epub Date: 2026-03-30DOI: 10.1016/j.phro.2026.100959
Riccardo Dal Bello , Serena Psoroulas , Dominik Flückiger , Jerome Krayenbühl , Arvid Kemper , Rafael Kranzer , Benjamin Côté , Jens von der Grün , Panagiotis Balermpas , Matthias Guckenberger , Stephanie Tanadini-Lang
Background and purpose
Ultra-high-dose-rate (UHDR) radiotherapy (RT) has emerged as a promising technique to widen the therapeutic window. However, clinical implementation is critically dependent on standardized dosimetry systems. This study reports on the integration of passive and active detectors for in-vivo dose monitoring in a clinical setting.
Materials and methods
Four detector systems were evaluated for patient treatments with UHDR at a modified C-arm linear accelerator (linac) (9 MeV, dose per pulse 1.08 Gy, average dose rate 216 Gy/s): two passive systems − optically stimulated luminescence detectors (OSLDs) and radiochromic films − and two active systems − a scintillator and a diamond detector. The detectors were positioned on a dedicated 3D-printed mount or the patient’s skin to measure integral dose and time-resolved parameters. OSLDs were calibrated against a reference ion chamber and validated under varying conditions. Scintillator and diamond detectors recorded pulse-to-pulse and intra-pulse stability, respectively.
Results
OSLDs provided reproducible dose reporting within ±5%, with precision improved through averaging multiple chips. The pulse-to-pulse stability measured with the scintillator was in agreement with the diamond detector measurements within ±1%. The diamond detector resolved intra-pulse stability and identified instabilities in case of poor beam tuning.
Conclusions
The combined use of OSLDs, scintillator, diamond, and film detectors enabled robust and time-resolved recording of UHDR RT in a clinical trial setting. While resource-intensive, this approach ensured redundancy and precision, providing a feasible strategy for early clinical adoption.
{"title":"Development and application of in-vivo dose and time-resolved measurements for clinical application of ultra-high dose rate radiotherapy","authors":"Riccardo Dal Bello , Serena Psoroulas , Dominik Flückiger , Jerome Krayenbühl , Arvid Kemper , Rafael Kranzer , Benjamin Côté , Jens von der Grün , Panagiotis Balermpas , Matthias Guckenberger , Stephanie Tanadini-Lang","doi":"10.1016/j.phro.2026.100959","DOIUrl":"10.1016/j.phro.2026.100959","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Ultra-high-dose-rate (UHDR) radiotherapy (RT) has emerged as a promising technique to widen the therapeutic window. However, clinical implementation is critically dependent on standardized dosimetry systems. This study reports on the integration of passive and active detectors for <em>in-vivo</em> dose monitoring in a clinical setting.</div></div><div><h3>Materials and methods</h3><div>Four detector systems were evaluated for patient treatments with UHDR at a modified C-arm linear accelerator (linac) (9 MeV, dose per pulse 1.08 Gy, average dose rate 216 Gy/s): two passive systems − optically stimulated luminescence detectors (OSLDs) and radiochromic films − and two active systems − a scintillator and a diamond detector. The detectors were positioned on a dedicated 3D-printed mount or the patient’s skin to measure integral dose and time-resolved parameters. OSLDs were calibrated against a reference ion chamber and validated under varying conditions. Scintillator and diamond detectors recorded pulse-to-pulse and intra-pulse stability, respectively.</div></div><div><h3>Results</h3><div>OSLDs provided reproducible dose reporting within ±5%, with precision improved through averaging multiple chips. The pulse-to-pulse stability measured with the scintillator was in agreement with the diamond detector measurements within ±1%. The diamond detector resolved intra-pulse stability and identified instabilities in case of poor beam tuning.</div></div><div><h3>Conclusions</h3><div>The combined use of OSLDs, scintillator, diamond, and film detectors enabled robust and time-resolved recording of UHDR RT in a clinical trial setting. While resource-intensive, this approach ensured redundancy and precision, providing a feasible strategy for early clinical adoption.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"38 ","pages":"Article 100959"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147600622","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}
Pub Date : 2026-03-01Epub Date: 2026-03-17DOI: 10.1016/j.phro.2026.100950
Szuzina Fazekas , Bettina K. Budai , Viktor Bérczi , Pál Maurovich Horvat , Zsolt Vizi
Accurate tissue delineation is essential in radiotherapy; however, conventional segmentation metrics mainly quantify geometric overlap and lack clinical interpretability. We proposed an automated Python-based evaluation pipeline using a bidirectional local distance-based metric that pairs test and reference contour points after center-of-mass correction and computes a similarity score from averaged Euclidean distances. The framework supports multislice images, multiple masks per slice, and concave mask separation, with open-source code provided. The method was demonstrated on fibroid and prostate MRI datasets, using 233 training cases and 12 test cases. In test examples, overlap scores exceeded 0.90, while Medical Similarity Index scores decreased to approximately 0.40.
{"title":"A clinically informed automated evaluation pipeline for medical image segmentation based on Medical Similarity Index","authors":"Szuzina Fazekas , Bettina K. Budai , Viktor Bérczi , Pál Maurovich Horvat , Zsolt Vizi","doi":"10.1016/j.phro.2026.100950","DOIUrl":"10.1016/j.phro.2026.100950","url":null,"abstract":"<div><div>Accurate tissue delineation is essential in radiotherapy; however, conventional segmentation metrics mainly quantify geometric overlap and lack clinical interpretability. We proposed an automated Python-based evaluation pipeline using a bidirectional local distance-based metric that pairs test and reference contour points after center-of-mass correction and computes a similarity score from averaged Euclidean distances. The framework supports multislice images, multiple masks per slice, and concave mask separation, with open-source code provided. The method was demonstrated on fibroid and prostate MRI datasets, using 233 training cases and 12 test cases. In test examples, overlap scores exceeded 0.90, while Medical Similarity Index scores decreased to approximately 0.40.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"38 ","pages":"Article 100950"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147600623","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}
Pub Date : 2026-03-01Epub Date: 2026-04-15DOI: 10.1016/j.phro.2026.100968
Kareem A. Wahid , William H. Nailon , Timothy D. Solberg
{"title":"Standardized reporting as a foundation for trustworthy and reproducible artificial intelligence in radiotherapy","authors":"Kareem A. Wahid , William H. Nailon , Timothy D. Solberg","doi":"10.1016/j.phro.2026.100968","DOIUrl":"10.1016/j.phro.2026.100968","url":null,"abstract":"","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"38 ","pages":"Article 100968"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147747301","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}
Pub Date : 2026-03-01Epub Date: 2026-03-06DOI: 10.1016/j.phro.2026.100942
Maximilian Grohmann , David Krug , Andrea Baehr , Cordula Petersen , Manuel Todorovic , Sebastian Schäfer , Lukas Clemens Böckelmann , Elisabetta Gargioni
Background and Purpose
Anatomical variations during prostate radiotherapy can cause discrepancies between planned and delivered doses, which may become more pronounced in (ultra-)hypofractionated regimens. However, a standardized method for accumulated dose assessment is lacking. This study presented and validated an efficient automated workflow for retrospective dose accumulation in moderately hypofractionated prostate treatments, avoiding deformable image registration and daily dose recalculation.
Materials and Methods
Twenty prostate cancer patients were analyzed retrospectively. The workflow combined daily cone-beam computed tomography (CBCT) imaging, online rigid registration, and artificial intelligence-based auto-contouring with planned dose data to estimate accumulated doses. Dose–volume metrics were analyzed for prostate, rectum, and bladder. Anatomical variations were assessed through volume and position analysis. Method accuracy was validated against CBCT-based dose recalculations in selected cases representing minimal and maximal variations.
Results
The workflow required about one minute per fraction. Interfractional volume variability (coefficient of variation) was 35.2 %, 20.6 %, and 9.5 % for bladder, rectum, and prostate, respectively. Mean prostate displacement was 3.49 ± 2.07 mm, and the dice similarity coefficient averaged 0.83 ± 0.08. Bladder dose metrics (V20Gy, V50Gy, mean) differed by > 2 % in 45–49 % of sessions, rectal metrics in 35–39 %. Accumulated dose estimates agreed within ± 2 % of CBCT-based recalculations.
Conclusions
Our automated workflow provides a robust, time-efficient method for monitoring interfractional dose variations in prostate radiotherapy. While constrained by CBCT image quality, the accuracy and practicality of the proposed method support its integration into clinical workflows, potentially improving offline adaptive decision-making.
{"title":"An efficient automated approach for accumulated dose estimation in prostate cancer radiotherapy","authors":"Maximilian Grohmann , David Krug , Andrea Baehr , Cordula Petersen , Manuel Todorovic , Sebastian Schäfer , Lukas Clemens Böckelmann , Elisabetta Gargioni","doi":"10.1016/j.phro.2026.100942","DOIUrl":"10.1016/j.phro.2026.100942","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Anatomical variations during prostate radiotherapy can cause discrepancies between planned and delivered doses, which may become more pronounced in (ultra-)hypofractionated regimens. However, a standardized method for accumulated dose assessment is lacking. This study presented and validated an efficient automated workflow for retrospective dose accumulation in moderately hypofractionated prostate treatments, avoiding deformable image registration and daily dose recalculation.</div></div><div><h3>Materials and Methods</h3><div>Twenty prostate cancer patients were analyzed retrospectively. The workflow combined daily cone-beam computed tomography (CBCT) imaging, online rigid registration, and artificial intelligence-based auto-contouring with planned dose data to estimate accumulated doses. Dose–volume metrics were analyzed for prostate, rectum, and bladder. Anatomical variations were assessed through volume and position analysis. Method accuracy was validated against CBCT-based dose recalculations in selected cases representing minimal and maximal variations.</div></div><div><h3>Results</h3><div>The workflow required about one minute per fraction. Interfractional volume variability (coefficient of variation) was 35.2 %, 20.6 %, and 9.5 % for bladder, rectum, and prostate, respectively. Mean prostate displacement was 3.49 ± 2.07 mm, and the dice similarity coefficient averaged 0.83 ± 0.08. Bladder dose metrics (V<sub>20Gy</sub>, V<sub>50Gy</sub>, mean) differed by > 2 % in 45–49 % of sessions, rectal metrics in 35–39 %. Accumulated dose estimates agreed within ± 2 % of CBCT-based recalculations.</div></div><div><h3>Conclusions</h3><div>Our automated workflow provides a robust, time-efficient method for monitoring interfractional dose variations in prostate radiotherapy. While constrained by CBCT image quality, the accuracy and practicality of the proposed method support its integration into clinical workflows, potentially improving offline adaptive decision-making.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"38 ","pages":"Article 100942"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147413717","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}
Pub Date : 2026-03-01Epub Date: 2026-02-21DOI: 10.1016/j.phro.2026.100936
Fionnbarr O’Grady , Lisa Stephenson , Martin Janson , Avani D. Rao , Ashish K. Chawla , Jiajin Fan , Peng Wang
Background and purpose
Previous studies have demonstrated that mini-ridge filters (MRF) can reduce beam delivery time in pencil beam scanning (PBS) proton therapy, but the effect on plan quality has not been analyzed in detail. Furthermore, the range modulation produced by the MRF may lead to an added benefit of reduced dose-averaged linear energy transfer (LETd) on the distal edge of the beam. The aim of this study is to demonstrate a statistically significant reduction in beam delivery time and distal LETd with a MRF without any degradation in plan quality.
Materials and methods
Twenty patient plans from a range of treatment sites, including five deep inspiration breath hold (DIBH) patients, have been re-optimized with a Monte Carlo based MRF beam model and compared to the corresponding clinical plans in beam delivery time, clinical acceptability, and a range of dose and LETd metrics.
Results
The average delivery time per beam decreased from (96.7 ± 4.9) s to (75.3 ± 4.0) s (p < 0.001). DIBH patients saw a reduction from (82.8 ± 15.5) s to (70.4 ± 12.7) s. The average reduction in maximum LETd to any organ-at-risk (OAR) within the 500 cGyRBE isodose line was (0.43 ± 0.06) keV/μm (p < 0.001). There was no significant difference in target dose homogeneity, conformality, robust target coverage, OAR dose metrics or LETd within the target.
Conclusions
MRFs can be used in PBS proton therapy to achieve a clinically relevant reduction in beam delivery time, and distal LETd without sacrificing plan quality.
{"title":"Reduced beam time and distal linear energy transfer with mini-ridge filters in pencil beam scanning proton therapy","authors":"Fionnbarr O’Grady , Lisa Stephenson , Martin Janson , Avani D. Rao , Ashish K. Chawla , Jiajin Fan , Peng Wang","doi":"10.1016/j.phro.2026.100936","DOIUrl":"10.1016/j.phro.2026.100936","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Previous studies have demonstrated that mini-ridge filters (MRF) can reduce beam delivery time in pencil beam scanning (PBS) proton therapy, but the effect on plan quality has not been analyzed in detail. Furthermore, the range modulation produced by the MRF may lead to an added benefit of reduced dose-averaged linear energy transfer (LET<sub>d</sub>) on the distal edge of the beam. The aim of this study is to demonstrate a statistically significant reduction in beam delivery time and distal LET<sub>d</sub> with a MRF without any degradation in plan quality.</div></div><div><h3>Materials and methods</h3><div>Twenty patient plans from a range of treatment sites, including five deep inspiration breath hold (DIBH) patients, have been re-optimized with a Monte Carlo based MRF beam model and compared to the corresponding clinical plans in beam delivery time, clinical acceptability, and a range of dose and LET<sub>d</sub> metrics.</div></div><div><h3>Results</h3><div>The average delivery time per beam decreased from (96.7 ± 4.9) s to (75.3 ± 4.0) s (p < 0.001). DIBH patients saw a reduction from (82.8 ± 15.5) s to (70.4 ± 12.7) s. The average reduction in maximum LET<sub>d</sub> to any organ-at-risk (OAR) within the 500 cGy<sub>RBE</sub> isodose line was (0.43 ± 0.06) keV/μm (p < 0.001). There was no significant difference in target dose homogeneity, conformality, robust target coverage, OAR dose metrics or LET<sub>d</sub> within the target.</div></div><div><h3>Conclusions</h3><div>MRFs can be used in PBS proton therapy to achieve a clinically relevant reduction in beam delivery time, and distal LET<sub>d</sub> without sacrificing plan quality.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"38 ","pages":"Article 100936"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147356926","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}
Pub Date : 2026-03-01Epub Date: 2026-03-22DOI: 10.1016/j.phro.2026.100953
Pietro Pisciotta, Adriaan Hengeveld, Erik W Korevaar, Sabine Visser, Dirk Wagenaar, Petra Klinker, John H. Maduro, Johannes A Langendijk, Anne GH Niezink, Stefan Both
Background and purpose
Mediastinal lymphoma patients are typically young and are at risk of long-term radiation-induced adverse events, making organ of interest (OOI) sparing a key objective of radiotherapy. This study investigated whether reducing setup uncertainty during robust intensity-modulated proton therapy (IMPT) planning is feasible without compromising target coverage and delivered dose robustness.
Materials and methods
Ten consecutive mediastinal lymphoma patients treated with IMPT were retrospectively analyzed. Treatment plans were generated on the four-dimensional average computed tomography (4DCT) using a 5 mm setup uncertainty (clinical standard). Additional plans with 4 and 3 mm setup uncertainties were created using a dose-mimicking optimization approach while maintaining identical clinical priorities. Robustness was evaluated using a three-dimensional robustness evaluation method (3DREM) and a longitudinal four-dimensional robustness evaluation method (4DREM), incorporating setup and range variations, machine uncertainties, respiratory motion, and weekly anatomical changes.
Results
All plans achieved adequate target coverage in the 3D-nominal and 4DREM voxel-wise mean dose distributions (V95 % > 99.6 %). The voxel-wise minimum dose distributions from 4DREM confirmed robust target coverage (V95 % > 98 %, D98 % > 95 % of prescription dose) for all setup uncertainties, with one clinically accepted exception. Reducing setup uncertainty resulted in statistically significant reductions in organs of interest doses (p < 0.01), corresponding to median reductions in predicted lifetime acute coronary event risk of 0.17 % and 0.32 % for 4 mm and 3 mm setup uncertainties, respectively (p < 0.01).
Conclusion
Reducing setup uncertainty during robust IMPT planning for mediastinal lymphoma patients was feasible and improved OOI sparing without compromising delivered dose robustness.
{"title":"Feasibility of reduced setup uncertainty in intensity-modulated proton therapy for mediastinal lymphoma","authors":"Pietro Pisciotta, Adriaan Hengeveld, Erik W Korevaar, Sabine Visser, Dirk Wagenaar, Petra Klinker, John H. Maduro, Johannes A Langendijk, Anne GH Niezink, Stefan Both","doi":"10.1016/j.phro.2026.100953","DOIUrl":"10.1016/j.phro.2026.100953","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Mediastinal lymphoma patients are typically young and are at risk of long-term radiation-induced adverse events, making organ of interest (OOI) sparing a key objective of radiotherapy. This study investigated whether reducing setup uncertainty during robust intensity-modulated proton therapy (IMPT) planning is feasible without compromising target coverage and delivered dose robustness.</div></div><div><h3>Materials and methods</h3><div>Ten consecutive mediastinal lymphoma patients treated with IMPT were retrospectively analyzed. Treatment plans were generated on the four-dimensional average computed tomography (4DCT) using a 5 mm setup uncertainty (clinical standard). Additional plans with 4 and 3 mm setup uncertainties were created using a dose-mimicking optimization approach while maintaining identical clinical priorities. Robustness was evaluated using a three-dimensional robustness evaluation method (3DREM) and a longitudinal four-dimensional robustness evaluation method (4DREM), incorporating setup and range variations, machine uncertainties, respiratory motion, and weekly anatomical changes.</div></div><div><h3>Results</h3><div>All plans achieved adequate target coverage in the 3D-nominal and 4DREM voxel-wise mean dose distributions (V<sub>95 %</sub> > 99.6 %). The voxel-wise minimum dose distributions from 4DREM confirmed robust target coverage (V<sub>95 %</sub> > 98 %, D<sub>98 %</sub> > 95 % of prescription dose) for all setup uncertainties, with one clinically accepted exception. Reducing setup uncertainty resulted in statistically significant reductions in organs of interest doses (p < 0.01), corresponding to median reductions in predicted lifetime acute coronary event risk of 0.17 % and 0.32 % for 4 mm and 3 mm setup uncertainties, respectively (p < 0.01).</div></div><div><h3>Conclusion</h3><div>Reducing setup uncertainty during robust IMPT planning for mediastinal lymphoma patients was feasible and improved OOI sparing without compromising delivered dose robustness.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"38 ","pages":"Article 100953"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147541427","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}
Pub Date : 2026-03-01DOI: 10.1016/j.phro.2026.100939
Eva van Weerd , Anne Lisa Wolf , Steven J.M. Habraken , Yvonne L.B. Klaver , Mischa S. Hoogeman
Background and purpose
Oesophageal radiotherapy may cause side effects due to high organs of interest (OOIs) doses. While proton therapy (PT) reduces OOI dose compared to photon therapy, setup robustness settings used may limit OOI sparing. This study assessed how optimizing robustness settings for adequate target coverage affected OOI dose, and evaluated the potential of online adaptive PT (OAPT).
Materials and methods
Twenty oesophageal cancer patients treated with intensity-modulated PT were analysed. Plans with 8 (clinical standard), 7, 6 and 5 mm setup robustness settings were generated on the planning 4D-CT (pCT) and robustly evaluated on weekly repeat 4D-CTs (rCTs). OAPT plans with individualized robustness settings were optimized and robustly evaluated on rCTs. Clinical target volume (CTV) V95% and OOI doses were assessed, and two-year mortality estimated using a validated model.
Results
A 5 mm setup robustness setting maintained CTV V95% ≥ 98% for 80% of patients, with 92.4–97.7% in the remaining 20%. With OAPT, V95% ≥ 98% was achieved in 75%, with 97.6–97.9% in the remaining 25%. Mean heart dose decreased from 11.8 Gy (RBE) (Inter Quartile Range (IQR) 10.9–13.9) to 9.2 Gy (RBE) (IQR 8.2–11.6) when reducing settings from 8 to 5 mm. OAPT provided a reduction of 3.7 Gy (RBE), reducing two-year mortality by 6.9% compared to the 8 mm setting.
Conclusions
Reducing setup robustness settings to 5 mm was feasible for most patients and reduced OOI dose. Large anatomical changes required plan adaptation. OAPT allowed further OOI dose reductions while preserving acceptable target coverage.
{"title":"Reduction of organ of interest dose in proton therapy for oesophageal cancer through optimized setup robustness settings and online adaptation","authors":"Eva van Weerd , Anne Lisa Wolf , Steven J.M. Habraken , Yvonne L.B. Klaver , Mischa S. Hoogeman","doi":"10.1016/j.phro.2026.100939","DOIUrl":"10.1016/j.phro.2026.100939","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Oesophageal radiotherapy may cause side effects due to high organs of interest (OOIs) doses. While proton therapy (PT) reduces OOI dose compared to photon therapy, setup robustness settings used may limit OOI sparing. This study assessed how optimizing robustness settings for adequate target coverage affected OOI dose, and evaluated the potential of online adaptive PT (OAPT).</div></div><div><h3>Materials and methods</h3><div>Twenty oesophageal cancer patients treated with intensity-modulated PT were analysed. Plans with 8 (clinical standard), 7, 6 and 5 mm setup robustness settings were generated on the planning 4D-CT (pCT) and robustly evaluated on weekly repeat 4D-CTs (rCTs). OAPT plans with individualized robustness settings were optimized and robustly evaluated on rCTs. Clinical target volume (CTV) V<sub>95%</sub> and OOI doses were assessed, and two-year mortality estimated using a validated model.</div></div><div><h3>Results</h3><div>A 5 mm setup robustness setting maintained CTV V<sub>95%</sub> ≥ 98% for 80% of patients, with 92.4–97.7% in the remaining 20%. With OAPT, V<sub>95%</sub> ≥ 98% was achieved in 75%, with 97.6–97.9% in the remaining 25%. Mean heart dose decreased from 11.8 Gy (RBE) (Inter Quartile Range (IQR) 10.9–13.9) to 9.2 Gy (RBE) (IQR 8.2–11.6) when reducing settings from 8 to 5 mm. OAPT provided a reduction of 3.7 Gy (RBE), reducing two-year mortality by 6.9% compared to the 8 mm setting.</div></div><div><h3>Conclusions</h3><div>Reducing setup robustness settings to 5 mm was feasible for most patients and reduced OOI dose. Large anatomical changes required plan adaptation. OAPT allowed further OOI dose reductions while preserving acceptable target coverage.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"38 ","pages":"Article 100939"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147413718","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}
Pub Date : 2026-03-01Epub Date: 2026-03-10DOI: 10.1016/j.phro.2026.100944
Thomas Opsommer , Mylène Messéant , Florence Le Tinier , Julien Laffarguette , Thomas Lacornerie , Frederik Crop
Free-breathing spine-based positioning/tracking in lung stereotactic body radiotherapy is required when direct tumor positioning is not possible. Respiratory baseline, motion and target position reproducibility interact and remain uncertainty sources. This results in conflicting margins but also clinical control. The internal target volume geometric reproducibility, spine distance dependency and four-dimensional per-fraction gross tumor volume (GTV) dose was analyzed in 340 fractions. While the target would leave a projected isotropic 5 mm planned target volume in 11% of fractions, ΔD98%(4D-GTV) > 10% occurred in 2.6% of fractions. Risk mitigation is suggested through additional off-line 4DCT, surface guidance, fractionation and increased inferior-superior and posterior-anterior margins.
{"title":"Internal target volume reproducibility and dose coverage for lung stereotactic body radiotherapy using spine-based positioning and tracking","authors":"Thomas Opsommer , Mylène Messéant , Florence Le Tinier , Julien Laffarguette , Thomas Lacornerie , Frederik Crop","doi":"10.1016/j.phro.2026.100944","DOIUrl":"10.1016/j.phro.2026.100944","url":null,"abstract":"<div><div>Free-breathing spine-based positioning/tracking in lung stereotactic body radiotherapy is required when direct tumor positioning is not possible. Respiratory baseline, motion and target position reproducibility interact and remain uncertainty sources. This results in conflicting margins but also clinical control. The internal target volume geometric reproducibility, spine distance dependency and four-dimensional per-fraction gross tumor volume (GTV) dose was analyzed in 340 fractions. While the target would leave a projected isotropic 5 mm planned target volume in 11% of fractions, ΔD<sub>98%</sub>(4D-GTV) > 10% occurred in 2.6% of fractions. Risk mitigation is suggested through additional off-line 4DCT, surface guidance, fractionation and increased inferior-superior and posterior-anterior margins.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"38 ","pages":"Article 100944"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147450517","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}
Pub Date : 2026-03-01Epub Date: 2026-03-18DOI: 10.1016/j.phro.2026.100949
Wonhyeong Lee , Yeon-Joo Kim , Jin Hee Kim , Sung-Ja Ahn , Jong Hoon Lee , Younghee Park , Jin Hwa Choi , Jin-ho Song , Yoonsun Chung
Background and purpose
A dummy run quality assurance was conducted for a prospective phase II trial of tailored radiotherapy (RT) according to the response after neoadjuvant chemotherapy (NAC) followed by surgery in locally advanced breast cancer (RTaNAC). Since inter-institutional variations in dose distributions can impact clinical outcomes, this dummy run aimed to develop an RT plan protocol to minimize these variations.
Material and methods
This study involved computed tomography images from three clinical scenarios: RT with no lymph node (LN) boost (Scenario 1), LN boost up to 60 Gy3.5, equivalent dose in 2 Gy fractions (EQD2) with α/β = 3.5 Gy (Scenario 2), and LN boost up to 66 Gy3.5 (Scenario 3). Seven institutions developed RT plans under a two-step process: first according to each institution’s policies (Step 1) and then using additional reference information, including artificial intelligence (AI) auto-contoured structures and LN boost target volume information (Step 2). Dose-volume histograms for breast and regional nodal areas were analyzed between the two steps.
Results
Inter-institutional variation observed in Step 1 improved in Step 2 for breast and regional nodal areas. Specifically for Scenario 1, dose coverage for the nodal clinical target volumes of the axillary level I LN improved from 57.5% to 97.5% (p-value = 0.075), and that of the supraclavicular LN improved from 75.6% to 88.8% (p-value = 0.046).
Conclusion
Variations in dose/volume metrics among institutions were mitigated by AI auto-contoured structures and LN boost target volume information. Through this dummy run, the participating institutions reached a consensus on an RT plan protocol to support multi-institutional expansion of RTaNAC.
{"title":"Quality assurance incorporating artificial intelligence-generated reference contours in a phase II radiotherapy trial","authors":"Wonhyeong Lee , Yeon-Joo Kim , Jin Hee Kim , Sung-Ja Ahn , Jong Hoon Lee , Younghee Park , Jin Hwa Choi , Jin-ho Song , Yoonsun Chung","doi":"10.1016/j.phro.2026.100949","DOIUrl":"10.1016/j.phro.2026.100949","url":null,"abstract":"<div><h3>Background and purpose</h3><div>A dummy run quality assurance was conducted for a prospective phase II trial of tailored radiotherapy (RT) according to the response after neoadjuvant chemotherapy (NAC) followed by surgery in locally advanced breast cancer (RTaNAC). Since inter-institutional variations in dose distributions can impact clinical outcomes, this dummy run aimed to develop an RT plan protocol to minimize these variations.</div></div><div><h3>Material and methods</h3><div>This study involved computed tomography images from three clinical scenarios: RT with no lymph node (LN) boost (Scenario 1), LN boost up to 60 Gy<sub>3.5</sub>, equivalent dose in 2 Gy fractions (EQD2) with α/β = 3.5 Gy (Scenario 2), and LN boost up to 66 Gy<sub>3.5</sub> (Scenario 3). Seven institutions developed RT plans under a two-step process: first according to each institution’s policies (Step 1) and then using additional reference information, including artificial intelligence (AI) auto-contoured structures and LN boost target volume information (Step 2). Dose-volume histograms for breast and regional nodal areas were analyzed between the two steps.</div></div><div><h3>Results</h3><div>Inter-institutional variation observed in Step 1 improved in Step 2 for breast and regional nodal areas. Specifically for Scenario 1, dose coverage for the nodal clinical target volumes of the axillary level I LN improved from 57.5% to 97.5% (p-value = 0.075), and that of the supraclavicular LN improved from 75.6% to 88.8% (p-value = 0.046).</div></div><div><h3>Conclusion</h3><div>Variations in dose/volume metrics among institutions were mitigated by AI auto-contoured structures and LN boost target volume information. Through this dummy run, the participating institutions reached a consensus on an RT plan protocol to support multi-institutional expansion of RTaNAC.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"38 ","pages":"Article 100949"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147541425","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}
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