Pub Date : 2025-10-01DOI: 10.1016/j.phro.2025.100845
Bart J.J. Kremers , Dave S.C. van Gruijthuijsen , Dominique Reijtenbagh , Jacco L.G. Steenhuijsen , Mariska de Smet , Rob H.N. Tijssen
This technical note evaluates the performance of an adaptive four-dimensional computed tomography (4DCT) acquisition method compared to conventional 4DCT using a motion phantom. Metrics assessed include deviations in volume, CT number, diameter, peak-to-peak amplitude and determination of the internal target volume (ITV) and mid-position. Under regular breathing, most measurements fall within predefined clinical tolerances for all systems. Under irregular motion, the adaptive method showed reduced deviations in ITV and minimal impact on mid-position determination. These findings support the clinical value of adaptive 4DCT in improving motion management and target definition accuracy in radiotherapy planning.
{"title":"A phantom study of internal target volume and mid-position accuracy in adaptive and conventional four-dimensional computed tomography across regular and irregular motion","authors":"Bart J.J. Kremers , Dave S.C. van Gruijthuijsen , Dominique Reijtenbagh , Jacco L.G. Steenhuijsen , Mariska de Smet , Rob H.N. Tijssen","doi":"10.1016/j.phro.2025.100845","DOIUrl":"10.1016/j.phro.2025.100845","url":null,"abstract":"<div><div>This technical note evaluates the performance of an adaptive four-dimensional computed tomography (4DCT) acquisition method compared to conventional 4DCT using a motion phantom. Metrics assessed include deviations in volume, CT number, diameter, peak-to-peak amplitude and determination of the internal target volume (ITV) and mid-position. Under regular breathing, most measurements fall within predefined clinical tolerances for all systems. Under irregular motion, the adaptive method showed reduced deviations in ITV and minimal impact on mid-position determination. These findings support the clinical value of adaptive 4DCT in improving motion management and target definition accuracy in radiotherapy planning.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100845"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268548","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 : 2025-10-01DOI: 10.1016/j.phro.2025.100847
Suryakant Kaushik , Nadine Vatterodt , Jakob Ödén , Albin Fredriksson , Stine S. Korreman , Iuliana Toma-Dasu
Head and neck (HN) radiotherapy often requires corrective interventions. This study evaluated three methods for synthetic computed tomography (CT) generation for adaptive HN planning using cone-beam CT (CBCT) images. CBCT images for 15 patients were paired with same-day repeat CT scans and robustly optimized proton plans were recalculated. The anatomy-preserving virtual CT (APvCT) method utilized organs-at-risk as deformation controlling structures. APvCT and conventional virtual CT methods showed lower mean absolute errors in CT number values compared to corrected CBCT; however, all synthetic CT methods were found suitable for proton dose recalculation with gamma passing rates greater than 96.7% ().
{"title":"Synthetic computed tomography techniques for adaptive proton therapy in head and neck cancers","authors":"Suryakant Kaushik , Nadine Vatterodt , Jakob Ödén , Albin Fredriksson , Stine S. Korreman , Iuliana Toma-Dasu","doi":"10.1016/j.phro.2025.100847","DOIUrl":"10.1016/j.phro.2025.100847","url":null,"abstract":"<div><div>Head and neck (HN) radiotherapy often requires corrective interventions. This study evaluated three methods for synthetic computed tomography (CT) generation for adaptive HN planning using cone-beam CT (CBCT) images. CBCT images for 15 patients were paired with same-day repeat CT scans and robustly optimized proton plans were recalculated. The anatomy-preserving virtual CT (APvCT) method utilized organs-at-risk as deformation controlling structures. APvCT and conventional virtual CT methods showed lower mean absolute errors in CT number values compared to corrected CBCT; however, all synthetic CT methods were found suitable for proton dose recalculation with gamma passing rates greater than 96.7% (<span><math><mrow><mn>2</mn><mtext>%</mtext><mo>,</mo><mn>2</mn><mspace></mspace><mi>mm</mi></mrow></math></span>).</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100847"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321176","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 : 2025-10-01DOI: 10.1016/j.phro.2025.100865
Gregory Buti , Marcela Giovenco , Tugba Yilmaz , Ali Ajdari , Christopher P. Bridge , Gregory C. Sharp , Fredrik Löfman , Helen A. Shih , Thomas Bortfeld
Background and purpose
Delineating clinical target volumes (CTVs) for glioma is challenging as consistency with the neuroanatomy needs to be carefully verified. We developed an automated approach that incorporates tumor infiltration pathways and anatomic barriers to improve the neuroanatomical consistency and efficiency of CTV delineation.
Materials and methods
A deep learning model for brain structure segmentation was developed based on manual delineations of hemispheres, brainstem, cerebellum, optic chiasm, optic nerves, ventricles, and midline on CT images of ninety-nine glioma patients. Brain structures predictions are integrated into a constrained distance transform that defines the CTV as a 15-mm expansion of the gross tumor volume. Connecting structures with white matter tracts allow for expansions across different structure boundaries, e.g., cerebellum and brainstem connecting at the cerebellar peduncles.
Results
Mean (±std) Dice Similarity Coefficient (DSC) for the hemispheres, brainstem, cerebel-lum, chiasm, optic nerves, midline and ventricles were (98.5 ± 0.8)%, (92.5 ± 2.8)%, (96.7 ± 2.2)% (63.9 ± 12.2)%, (83.8 ± 9.0)%, (81.2 ± 7.0) and (91.5 ± 3.9)%. Mean (±std) 95 % Hausdorff distance (HD95) were, in mm, 1.9 ± 2.5, 7.0 ± 5.4, 1.8 ± 1.2, 7.2 ± 3.2, 2.3 ± 1.0, 9.5 ± 10.5, and 3.8 ± 3.1, respectively. Auto-generated CTVs are compared against reference CTVs (15-mm expansion constrained by manually-contoured brain structures). The automatic CTVs showed excellent similarity to the reference CTVs with mean (±std) Surface DSC with 2 mm tolerance and HD95 scores of (95.6 ± 3.4)% and (1.4 ± 1.2) mm, respectively. A physician’s quality assessment reported that the automated method would result in a substantial amount of time saved in 85 % of CTV delineations.
Conclusion
We have successfully incorporated expert knowledge to improve the neuroanatom-ical consistency of automatically-generated CTVs for glioma.
{"title":"Clinical target volumes for glioma – Automated delineation to improve neuroanatomic consistency","authors":"Gregory Buti , Marcela Giovenco , Tugba Yilmaz , Ali Ajdari , Christopher P. Bridge , Gregory C. Sharp , Fredrik Löfman , Helen A. Shih , Thomas Bortfeld","doi":"10.1016/j.phro.2025.100865","DOIUrl":"10.1016/j.phro.2025.100865","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Delineating clinical target volumes (CTVs) for glioma is challenging as consistency with the neuroanatomy needs to be carefully verified. We developed an automated approach that incorporates tumor infiltration pathways and anatomic barriers to improve the neuroanatomical consistency and efficiency of CTV delineation.</div></div><div><h3>Materials and methods</h3><div>A deep learning model for brain structure segmentation was developed based on manual delineations of hemispheres, brainstem, cerebellum, optic chiasm, optic nerves, ventricles, and midline on CT images of ninety-nine glioma patients. Brain structures predictions are integrated into a constrained distance transform that defines the CTV as a 15-mm expansion of the gross tumor volume. Connecting structures with white matter tracts allow for expansions across different structure boundaries, e.g., cerebellum and brainstem connecting at the cerebellar peduncles.</div></div><div><h3>Results</h3><div>Mean (±std) Dice Similarity Coefficient (DSC) for the hemispheres, brainstem, cerebel-lum, chiasm, optic nerves, midline and ventricles were (98.5 ± 0.8)%, (92.5 ± 2.8)%, (96.7 ± 2.2)% (63.9 ± 12.2)%, (83.8 ± 9.0)%, (81.2 ± 7.0) and (91.5 ± 3.9)%. Mean (±std) 95 % Hausdorff distance (HD95) were, in mm, 1.9 ± 2.5, 7.0 ± 5.4, 1.8 ± 1.2, 7.2 ± 3.2, 2.3 ± 1.0, 9.5 ± 10.5, and 3.8 ± 3.1, respectively. Auto-generated CTVs are compared against reference CTVs (15-mm expansion constrained by manually-contoured brain structures). The automatic CTVs showed excellent similarity to the reference CTVs with mean (±std) Surface DSC with 2 mm tolerance and HD95 scores of (95.6 ± 3.4)% and (1.4 ± 1.2) mm, respectively. A physician’s quality assessment reported that the automated method would result in a substantial amount of time saved in 85 % of CTV delineations.</div></div><div><h3>Conclusion</h3><div>We have successfully incorporated expert knowledge to improve the neuroanatom-ical consistency of automatically-generated CTVs for glioma.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100865"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576303","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 : 2025-10-01DOI: 10.1016/j.phro.2025.100866
Christina Sarosiek, Asma Amjad, Renae Conlin, Beth Erickson, William A. Hall, Eric S. Paulson
Introduction
The adapt-to-shape (ATS) process on the MR-Linac involves manual contour edits followed by treatment plan re-optimization on daily pre-beam MRIs. A verification image is acquired after plan optimization to assess the dose distribution with respect to intrafraction motion using the pre-beam contours. We introduce here a workflow to automatically detect organ motion of gastrointestinal structures that results in exceeded planned dose constraints.
Materials and methods
The workflow first transferred the contours and dose distribution created on the daily pre-beam MRI to the verification MRI. A deep learning-refined contour propagation (DL-RCP) tool, trained on 79 images, improved the transferred contours and the dose to 0.03 cm3 (D0.03 cm3) is updated. The workflow notified the physician if D0.03 cm3 exceeds the constraint. We tested the workflow on 48 daily ATS fractions of 11 patients treated for pancreatic cancer (33–40 Gy in 5 fractions). We added manually drawn contours to the verification images for reference.
Results
The Dice similarity coefficient and mean distance to agreement for the clinical/DL-refined contours were 0.56/0.71 and 9.08/5.08 mm, respectively. The workflow detected exceeded constraints with specificity 0.90, sensitivity 0.75, and accuracy 0.85. In one case, the duodenal D0.03 cm3 was 29.9 Gy for the clinical contour, and 36.0 Gy and 35.6 Gy with the reference and DL-refined contours.
Conclusion
The proposed method detected exceeded dose constraints in gastrointestinal structures due to intrafraction motion during ATS planning for pancreatic treatments and can aid in the clinical decision to re-optimize the plan on the verification MR.
{"title":"Workflow to detect exceeded dose constraints in pancreatic stereotactic body irradiation after intrafraction motion during magnetic resonance-guided adaptive radiotherapy using a deep learning-refined contour propagation tool","authors":"Christina Sarosiek, Asma Amjad, Renae Conlin, Beth Erickson, William A. Hall, Eric S. Paulson","doi":"10.1016/j.phro.2025.100866","DOIUrl":"10.1016/j.phro.2025.100866","url":null,"abstract":"<div><h3>Introduction</h3><div>The adapt-to-shape (ATS) process on the MR-Linac involves manual contour edits followed by treatment plan re-optimization on daily pre-beam MRIs. A verification image is acquired after plan optimization to assess the dose distribution with respect to intrafraction motion using the pre-beam contours. We introduce here a workflow to automatically detect organ motion of gastrointestinal structures that results in exceeded planned dose constraints.</div></div><div><h3>Materials and methods</h3><div>The workflow first transferred the contours and dose distribution created on the daily pre-beam MRI to the verification MRI. A deep learning-refined contour propagation (DL-RCP) tool, trained on 79 images, improved the transferred contours and the dose to 0.03 cm<sup>3</sup> (D<sub>0.03 cm<sup>3</sup></sub>) is updated. The workflow notified the physician if D<sub>0.03 cm<sup>3</sup></sub> exceeds the constraint. We tested the workflow on 48 daily ATS fractions of 11 patients treated for pancreatic cancer (33–40 Gy in 5 fractions). We added manually drawn contours to the verification images for reference.</div></div><div><h3>Results</h3><div>The Dice similarity coefficient and mean distance to agreement for the clinical/DL-refined contours were 0.56/0.71 and 9.08/5.08 mm, respectively. The workflow detected exceeded constraints with specificity 0.90, sensitivity 0.75, and accuracy 0.85. In one case, the duodenal D<sub>0.03 cm<sup>3</sup></sub> was 29.9 Gy for the clinical contour, and 36.0 Gy and 35.6 Gy with the reference and DL-refined contours.</div></div><div><h3>Conclusion</h3><div>The proposed method detected exceeded dose constraints in gastrointestinal structures due to intrafraction motion during ATS planning for pancreatic treatments and can aid in the clinical decision to re-optimize the plan on the verification MR.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100866"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576372","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 : 2025-10-01DOI: 10.1016/j.phro.2025.100855
Oscar Casares-Magaz , Renata G. Raidou , Katarina Furmanová , Niclas Pettersson , Vitali Moiseenko , John Einck , Austin Hopper , Rick Knopp , Ludvig P. Muren
Background and purpose
The risk of genitourinary late effects is a major dose-limiting factor in radiotherapy for prostate cancer. By using shape analysis and machine learning, the aim of this study was to evaluate whether bladder shape descriptors from the first week of treatment could identify patients experiencing genitourinary late effects.
Material and methods
From a cohort of 258 prostate cancer patients treated with daily cone-beam computed tomography (CBCT)-guided radiotherapy (prescription doses of 77.4–81.0 Gy), 7 pre-treatment asymptomatic cases experiencing RTOG genitourinary late effects ≥Grade 2 and 21 matched controls were selected. The bladder was manually contoured on each CBCT, and a 17-D vector comprising shape descriptors was used for patient clustering, focusing on bladder contours from the first week of treatment. ANOVA was used to test statistical significance of descriptors across and within clusters.
Results
Of the contours from the first week of treatment, 84 % could be classified in two main clusters with distinct bladder shape characteristics. This cluster stratification remained identical when bladder contours from the entire course of treatment were used. Convexity, elliptic variance and compactness were significantly different between patients with vs. without genitourinary late effects ≥Grade 2 (p < 0.05). Dice Coefficients between predictive models using descriptors of the first week and the voxels’ probability of belonging to the bladder were above 93 ± 6 % (median ± interquartile range).
Conclusion
Bladder shape descriptors in the first week of treatment showed potential to predict the risk of developing genitourinary late effects after radiotherapy for prostate cancer.
{"title":"Risk of genitourinary late effects after radiotherapy for prostate cancer associated with early changes in bladder shape","authors":"Oscar Casares-Magaz , Renata G. Raidou , Katarina Furmanová , Niclas Pettersson , Vitali Moiseenko , John Einck , Austin Hopper , Rick Knopp , Ludvig P. Muren","doi":"10.1016/j.phro.2025.100855","DOIUrl":"10.1016/j.phro.2025.100855","url":null,"abstract":"<div><h3>Background and purpose</h3><div>The risk of genitourinary late effects is a major dose-limiting factor in radiotherapy for prostate cancer. By using shape analysis and machine learning, the aim of this study was to evaluate whether bladder shape descriptors from the first week of treatment could identify patients experiencing genitourinary late effects.</div></div><div><h3>Material and methods</h3><div>From a cohort of 258 prostate cancer patients treated with daily cone-beam computed tomography (CBCT)-guided radiotherapy (prescription doses of 77.4–81.0 Gy), 7 pre-treatment asymptomatic cases experiencing RTOG genitourinary late effects ≥Grade 2 and 21 matched controls were selected. The bladder was manually contoured on each CBCT, and a 17-D vector comprising shape descriptors was used for patient clustering, focusing on bladder contours from the first week of treatment. ANOVA was used to test statistical significance of descriptors across and within clusters.</div></div><div><h3>Results</h3><div>Of the contours from the first week of treatment, 84 % could be classified in two main clusters with distinct bladder shape characteristics. This cluster stratification remained identical when bladder contours from the entire course of treatment were used. Convexity, elliptic variance and compactness were significantly different between patients with vs. without genitourinary late effects ≥Grade 2 (<em>p</em> < 0.05). Dice Coefficients between predictive models using descriptors of the first week and the voxels’ probability of belonging to the bladder were above 93 ± 6 % (median ± interquartile range).</div></div><div><h3>Conclusion</h3><div>Bladder shape descriptors in the first week of treatment showed potential to predict the risk of developing genitourinary late effects after radiotherapy for prostate cancer.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100855"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417032","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 : 2025-10-01DOI: 10.1016/j.phro.2025.100853
Evangelia Choulilitsa , Katarzyna Czerska , Barbara Bachtiary , Damien Charles Weber , Antony John Lomax , Francesca Albertini
Background and purpose
Standard care for head and neck cancer (HNC) treatment with proton therapy typically involves a 4–6 field Intensity Modulated Proton Therapy plan to enhance robustness towards anatomical changes and patient misalignments. This study aimed to evaluate whether a more efficient plan with fewer beams, designed for faster delivery, can be combined with online daily adaptation (DAPT) to provide treatment of comparable quality, and improve treatment outcomes.
Materials and methods
We retrospectively analyzed five HNC patients with available daily 3D imaging treated at our institution. To simulate DAPT, synthetic Computed Tomography (CT) images were generated by deforming planning CT to each daily Cone-Beam CT with targets and organs-at-risk (OARs) propagated to daily images. Three plans were created per-patient: OfflineSBC and DAPTSBC with standard, and DAPTRBC with reduced, beam configuration. DAPTSBC and DAPTRBC were reoptimized on daily synCTs, while OfflineSBC followed clinical workflow, with offline replanning as needed.
Results
OfflineSBC showed >5% target underdosage in 15% of fractions, with both adaptive approaches significantly improving coverage. Although DAPTRBC outperformed OfflineSBC for target coverage, its advantage in OARs sparing was less definitive. DAPTSBC reduced pooled average normal tissue dose across patients and fractions by 13% and pooled average normal tissue complication probability for xerostomia by 7%. Delivery of DAPTRBC with fewer beams was 24% faster than plans with conventional arrangement.
Conclusions
Our delivery efficiency study shows that DAPT can allow fewer beams to achieve faster delivery, as shown in case of DAPTRBC workflow, and a reduction in the dose to normal tissue.
{"title":"Time-saving potential of daily online adaptive proton therapy for head and neck cancers by reducing number of beams","authors":"Evangelia Choulilitsa , Katarzyna Czerska , Barbara Bachtiary , Damien Charles Weber , Antony John Lomax , Francesca Albertini","doi":"10.1016/j.phro.2025.100853","DOIUrl":"10.1016/j.phro.2025.100853","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Standard care for head and neck cancer (HNC) treatment with proton therapy typically involves a 4–6 field Intensity Modulated Proton Therapy plan to enhance robustness towards anatomical changes and patient misalignments. This study aimed to evaluate whether a more efficient plan with fewer beams, designed for faster delivery, can be combined with online daily adaptation (DAPT) to provide treatment of comparable quality, and improve treatment outcomes.</div></div><div><h3>Materials and methods</h3><div>We retrospectively analyzed five HNC patients with available daily 3D imaging treated at our institution. To simulate DAPT, synthetic Computed Tomography (CT) images were generated by deforming planning CT to each daily Cone-Beam CT with targets and organs-at-risk (OARs) propagated to daily images. Three plans were created per-patient: Offline<sub>SBC</sub> and DAPT<sub>SBC</sub> with standard, and DAPT<sub>RBC</sub> with reduced, beam configuration. DAPT<sub>SBC</sub> and DAPT<sub>RBC</sub> were reoptimized on daily synCTs, while Offline<sub>SBC</sub> followed clinical workflow, with offline replanning as needed.</div></div><div><h3>Results</h3><div>Offline<sub>SBC</sub> showed >5% target underdosage in 15% of fractions, with both adaptive approaches significantly improving coverage. Although DAPT<sub>RBC</sub> outperformed Offline<sub>SBC</sub> for target coverage, its advantage in OARs sparing was less definitive. DAPT<sub>SBC</sub> reduced pooled average normal tissue dose across patients and fractions by 13% and pooled average normal tissue complication probability for xerostomia by 7%. Delivery of DAPT<sub>RBC</sub> with fewer beams was 24% faster than plans with conventional arrangement.</div></div><div><h3>Conclusions</h3><div>Our delivery efficiency study shows that DAPT can allow fewer beams to achieve faster delivery, as shown in case of DAPT<sub>RBC</sub> workflow, and a reduction in the dose to normal tissue.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100853"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363046","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 : 2025-10-01DOI: 10.1016/j.phro.2025.100867
David Nash , Sarah Muscat , Chelmis M. Thiong’o , Eliana Vasquez Osorio , Antony L. Palmer
Background and purpose
Reirradiation is increasingly common, but accounting for prior dose to the spinal cord and brainstem is challenging. This study compares a simple isodose-based method of previous dose compensation with voxel-wise equivalent dose in 2 Gy fractions (EQD2/2) dose mapping to assess accuracy and safety.
Materials and methods
Ten head and neck reirradiation cases were retrospectively reviewed. During planning, original dose distributions were mapped onto the reirradiation computed tomography scan. Isodoses within the cord and brainstem were used to segment dose-level substructures, with cumulative doses kept within defined tolerances. Following 3D EQD2/2 mapping, the same cases were audited by recalculating cumulative maximum doses. Cumulative doses from both methods were compared.
Results
Retrospective EQD2/2 analysis confirmed all cumulative doses were within tolerance, with up to 9.7 Gy difference between the two methods. In two cases, cord and brainstem doses approached tolerance.
Conclusions
A simple, isodose-based approach to spinal cord and brainstem reirradiation tolerance calculation has been shown to be safe when retrospectively compared with voxel-wise EQD2/2 mapping. This method can be implemented in any planning system capable of generating contours from isodose lines, offering a practical alternative where advanced EQD2/2 dose accumulation software is unavailable.
{"title":"Using three-dimensional equieffective dose mapping to audit a methodology for calculating permitted doses for head and neck reirradiation","authors":"David Nash , Sarah Muscat , Chelmis M. Thiong’o , Eliana Vasquez Osorio , Antony L. Palmer","doi":"10.1016/j.phro.2025.100867","DOIUrl":"10.1016/j.phro.2025.100867","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Reirradiation is increasingly common, but accounting for prior dose to the spinal cord and brainstem is challenging. This study compares a simple isodose-based method of previous dose compensation with voxel-wise equivalent dose in 2 Gy fractions (EQD<sub>2/2</sub>) dose mapping to assess accuracy and safety.</div></div><div><h3>Materials and methods</h3><div>Ten head and neck reirradiation cases were retrospectively reviewed. During planning, original dose distributions were mapped onto the reirradiation computed tomography scan. Isodoses within the cord and brainstem were used to segment dose-level substructures, with cumulative doses kept within defined tolerances. Following 3D EQD<sub>2/2</sub> mapping, the same cases were audited by recalculating cumulative maximum doses. Cumulative doses from both methods were compared.</div></div><div><h3>Results</h3><div>Retrospective EQD<sub>2/2</sub> analysis confirmed all cumulative doses were within tolerance, with up to 9.7 Gy difference between the two methods. In two cases, cord and brainstem doses approached tolerance.</div></div><div><h3>Conclusions</h3><div>A simple, isodose-based approach to spinal cord and brainstem reirradiation tolerance calculation has been shown to be safe when retrospectively compared with voxel-wise EQD<sub>2/2</sub> mapping. This method can be implemented in any planning system capable of generating contours from isodose lines, offering a practical alternative where advanced EQD<sub>2/2</sub> dose accumulation software is unavailable.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100867"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614239","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 : 2025-10-01DOI: 10.1016/j.phro.2025.100874
Nathan Torelli , Jonas Willmann , Katja Dähler , Madalyne Day , Nicolaus Andratschke , Jan Unkelbach
Background and purpose
Reirradiation for non-small cell lung cancer (NSCLC) is commonly delivered using coplanar techniques. In this study, we investigated whether the selection of favorable non-coplanar beam orientations may limit cumulative doses to critical organs-at-risk (OARs) and thus improve the therapeutic window.
Materials and methods
Fifteen cases of challenging high-dose reirradiation for locoregionally recurrent NSCLC were included in this in-silico study. For each patient, the dose distribution from the previous treatment was first mapped to the new patient anatomy using rigid dose registration, and subsequently converted to equivalent dose in 2 Gy fractions (EQD2). A two-arc non-coplanar reirradiation plan was then generated using an EQD2-based direct aperture optimization algorithm, which allows for the simultaneous optimization of dynamic gantry-couch paths and the cumulative EQD2 distribution. Non-coplanar reirradiation plans were benchmarked against two-arc coplanar plans.
Results
Considerable reductions of at least 5 Gy in the maximum cumulative EQD2 to critical organs were achieved in 6 out of 15 patients using non-coplanar versus coplanar arcs. In particular, the maximum cumulative EQD2 was reduced by up to −9.0 Gy for the bronchial tree, −5.8 Gy for the esophagus, −5.3 Gy for the trachea and −5.6 Gy for the great vessel. At the same time, target coverage and lung EQD2 metrics were comparable for both methods.
Conclusions
The automated selection of favorable non-coplanar beam orientations may reduce the maximum cumulative EQD2 to critical OARs in challenging thoracic reirradiation cases. This allows to explore either better OAR sparing or dose-escalation in future clinical studies.
{"title":"Improving reirradiation of recurrent non-small cell lung cancer through non-coplanar beam arrangements","authors":"Nathan Torelli , Jonas Willmann , Katja Dähler , Madalyne Day , Nicolaus Andratschke , Jan Unkelbach","doi":"10.1016/j.phro.2025.100874","DOIUrl":"10.1016/j.phro.2025.100874","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Reirradiation for non-small cell lung cancer (NSCLC) is commonly delivered using coplanar techniques. In this study, we investigated whether the selection of favorable non-coplanar beam orientations may limit cumulative doses to critical organs-at-risk (OARs) and thus improve the therapeutic window.</div></div><div><h3>Materials and methods</h3><div>Fifteen cases of challenging high-dose reirradiation for locoregionally recurrent NSCLC were included in this in-silico study. For each patient, the dose distribution from the previous treatment was first mapped to the new patient anatomy using rigid dose registration, and subsequently converted to equivalent dose in 2 Gy fractions (EQD2). A two-arc non-coplanar reirradiation plan was then generated using an EQD2-based direct aperture optimization algorithm, which allows for the simultaneous optimization of dynamic gantry-couch paths and the cumulative EQD2 distribution. Non-coplanar reirradiation plans were benchmarked against two-arc coplanar plans.</div></div><div><h3>Results</h3><div>Considerable reductions of at least 5 Gy in the maximum cumulative EQD2 to critical organs were achieved in 6 out of 15 patients using non-coplanar versus coplanar arcs. In particular, the maximum cumulative EQD2 was reduced by up to −9.0 Gy for the bronchial tree, −5.8 Gy for the esophagus, −5.3 Gy for the trachea and −5.6 Gy for the great vessel. At the same time, target coverage and lung EQD2 metrics were comparable for both methods.</div></div><div><h3>Conclusions</h3><div>The automated selection of favorable non-coplanar beam orientations may reduce the maximum cumulative EQD2 to critical OARs in challenging thoracic reirradiation cases. This allows to explore either better OAR sparing or dose-escalation in future clinical studies.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100874"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614363","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 : 2025-10-01DOI: 10.1016/j.phro.2025.100868
Maddalena M.G. Rossi, Barbara Stam, Iris Walraven , Jose A. Belderbos, Jan-Jakob Sonke
Background and purpose
Tumour position may change after the acquisition of an initial cone-beam computed-tomography for setup correction (CBCTPreCor). In this study, the impact of post-correction validation (CBCTVal) and intra-arc scans (CBCTIA) on intrafraction tumour misalignment during volumetric-modulated-arc-therapy (VMAT) lung stereotactic-body radiotherapy (SBRT) was evaluated.
Material and methods
Early stage lung cancer patients (n = 167) treated with VMAT SBRT had the following image guided (IG)RT protocol: (1) CBCTPreCor, (2) CBCTVal to verify tumour alignment, (3) an intra-arc scan (CBCTIA) during both VMAT arcs. Additional corrections were made for residual misalignments ≥0.3 cm. The actual and two simulated protocols were analysed: (1) clinical (CBCTClin), (2) simulations without validation scans (CBCTNo_Val), (3) simulations without repeat CBCTs (CBCTNo_IFMM). Grand-mean (GM), systematic (∑) and random (σ) tumour misalignment in CBCTIA-1 and CBCTIA-2 were calculated. Patient characteristics were evaluated for association with extra validation scans.
Results
CBCTVal triggered a second correction in 20.4 % of fractions in 47 % of patients and CBCTIA-1 in 14.4 % of fractions in 40 % of patients. Omitting CBCTVal increased ∑ and σ ranging from 27–30 % and 20–45 % for the different directions. Omitting also CBCTIA further increased ∑ ranging from 55–90 %. Omitting CBCTVal and CBCTIA would require a 1–2 mm planning target volume margin increase. Respiratory amplitude and body mass index (BMI) were significantly associated with extra corrections (area under the curve: 0.75).
Conclusion
This study demonstrates that CBCTVal and CBCTIA-1 reduce geometric uncertainties in VMAT lung SBRT. Respiratory amplitude and BMI were significantly associated with extra corrections but cannot reliably identify patients requiring extra validation scans.
{"title":"Impact of post-correction validation scans on intrafraction tumour misalignment in lung stereotactic body radiotherapy","authors":"Maddalena M.G. Rossi, Barbara Stam, Iris Walraven , Jose A. Belderbos, Jan-Jakob Sonke","doi":"10.1016/j.phro.2025.100868","DOIUrl":"10.1016/j.phro.2025.100868","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Tumour position may change after the acquisition of an initial cone-beam computed-tomography for setup correction (CBCT<sup>PreCor</sup>). In this study, the impact of post-correction validation (CBCT<sup>Val</sup>) and intra-arc scans (CBCT<sup>IA</sup>) on intrafraction tumour misalignment during volumetric-modulated-arc-therapy (VMAT) lung stereotactic-body radiotherapy (SBRT) was evaluated.</div></div><div><h3>Material and methods</h3><div>Early stage lung cancer patients (n = 167) treated with VMAT SBRT had the following image guided (IG)RT protocol: (1) CBCT<sup>PreCor</sup>, (2) CBCT<sup>Val</sup> to verify tumour alignment, (3) an intra-arc scan (CBCT<sup>IA</sup>) during both VMAT arcs. Additional corrections were made for residual misalignments ≥0.3 cm. The actual and two simulated protocols were analysed: (1) clinical (CBCT<sup>Clin</sup>), (2) simulations without validation scans (CBCT<sup>No_Val</sup>), (3) simulations without repeat CBCTs (CBCT<sup>No_IFMM</sup>). Grand-mean (GM), systematic (∑) and random (σ) tumour misalignment in CBCT<sup>IA-1</sup> and CBCT<sup>IA-2</sup> were calculated. Patient characteristics were evaluated for association with extra validation scans.</div></div><div><h3>Results</h3><div>CBCT<sup>Val</sup> triggered a second correction in 20.4 % of fractions in 47 % of patients and CBCT<sup>IA-1</sup> in 14.4 % of fractions in 40 % of patients. Omitting CBCT<sup>Val</sup> increased ∑ and σ ranging from 27–30 % and 20–45 % for the different directions. Omitting also CBCT<sup>IA</sup> further increased ∑ ranging from 55–90 %. Omitting CBCT<sup>Val</sup> and CBCT<sup>IA</sup> would require a 1–2 mm planning target volume margin increase. Respiratory amplitude and body mass index (BMI) were significantly associated with extra corrections (area under the curve: 0.75).</div></div><div><h3>Conclusion</h3><div>This study demonstrates that CBCT<sup>Val</sup> and CBCT<sup>IA-1</sup> reduce geometric uncertainties in VMAT lung SBRT. Respiratory amplitude and BMI were significantly associated with extra corrections but cannot reliably identify patients requiring extra validation scans.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100868"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614361","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 : 2025-10-01DOI: 10.1016/j.phro.2025.100885
Carmen Seller-Oria, Suzanne van Beek, Suzan Gerrets, Sanne van Weerdenburg, Paula Bos, Simon van Kranen, Marloes Frantzen-Steneker, Zeno Gouw, Jan-Jakob Sonke, Peter Remeijer
Background and purpose
Locally advanced lung cancer patients are commonly treated with daily cone beam CT (CBCT) guided radiotherapy using one treatment isocenter. Due to differential motion between primary tumor (GTVprim) and affected lymph nodes, a compromise needs to be made during daily patient alignment, requiring enlarged treatment margins. In this work, an online adaptive (OART) strategy was proposed to correct for residual target misalignments and enable treatment margin reduction.
Material and methods
We developed in-house an application that produced a synthetic CT (sCT) and delineations to correct for residual target misalignments. A deformation vector field (DVF) was created by using conventional CBCT-to-CT rigid target registrations. The DVF was applied to the planning CT (pCT) and delineations to generate a sCT where GTVprim was loco-rigidly shifted into the correct position. Twenty CBCTs of eight patients were selected to assess sCTs in terms of GTVprim position (via CBCT-to-sCT and CBCT-to-pCT registration vector lengths), pixel-wise sCT-pCT Hounsfield unit (HU) errors inside GTVprim, and sCT-pCT GTVprim volume differences.
Results
Median vector lengths were 5.1 mm relative to pCTs, and 0.7 mm relative to sCTs, demonstrating the ability of the proposed tool to correct residual misalignments. Median HU errors across all scans were within 1 HU, and the median GTVprim volume difference was −3.7 %.
Conclusions
A correction method for residual target misalignments in locally advanced lung cancer patients was proposed. It automatically produces sCTs and delineations, enabling OART implementation without the need for manual delineation corrections, and with potentially smaller treatment margins.
{"title":"Automated target misalignment correction for cone beam computed tomography-based online adaptive radiotherapy of locally advanced lung cancer patients","authors":"Carmen Seller-Oria, Suzanne van Beek, Suzan Gerrets, Sanne van Weerdenburg, Paula Bos, Simon van Kranen, Marloes Frantzen-Steneker, Zeno Gouw, Jan-Jakob Sonke, Peter Remeijer","doi":"10.1016/j.phro.2025.100885","DOIUrl":"10.1016/j.phro.2025.100885","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Locally advanced lung cancer patients are commonly treated with daily cone beam CT (CBCT) guided radiotherapy using one treatment isocenter. Due to differential motion between primary tumor (GTV<sub>prim</sub>) and affected lymph nodes, a compromise needs to be made during daily patient alignment, requiring enlarged treatment margins. In this work, an online adaptive (OART) strategy was proposed to correct for residual target misalignments and enable treatment margin reduction.</div></div><div><h3>Material and methods</h3><div>We developed in-house an application that produced a synthetic CT (sCT) and delineations to correct for residual target misalignments. A deformation vector field (DVF) was created by using conventional CBCT-to-CT rigid target registrations. The DVF was applied to the planning CT (pCT) and delineations to generate a sCT where GTV<sub>prim</sub> was loco-rigidly shifted into the correct position. Twenty CBCTs of eight patients were selected to assess sCTs in terms of GTV<sub>prim</sub> position (via CBCT-to-sCT and CBCT-to-pCT registration vector lengths), pixel-wise sCT-pCT Hounsfield unit (HU) errors inside GTV<sub>prim</sub>, and sCT-pCT GTV<sub>prim</sub> volume differences.</div></div><div><h3>Results</h3><div>Median vector lengths were 5.1 mm relative to pCTs, and 0.7 mm relative to sCTs, demonstrating the ability of the proposed tool to correct residual misalignments. Median HU errors across all scans were within 1 HU, and the median GTV<sub>prim</sub> volume difference was −3.7 %.</div></div><div><h3>Conclusions</h3><div>A correction method for residual target misalignments in locally advanced lung cancer patients was proposed. It automatically produces sCTs and delineations, enabling OART implementation without the need for manual delineation corrections, and with potentially smaller treatment margins.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100885"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145680903","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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