Physics and Imaging in Radiation Oncology最新文献

{"title":"Comparison of cone beam computed tomography post-processing methods for online adaptive proton therapy of prostate cancer","authors":"Mislav Bobić ,&nbsp;Daniel H. Bushe ,&nbsp;Hoyeon Lee ,&nbsp;Brian A. Winey ,&nbsp;Jason A. Efstathiou ,&nbsp;Harald Paganetti ,&nbsp;Jennifer Pursley ,&nbsp;Nils Peters ,&nbsp;Lena Nenoff","doi":"10.1016/j.phro.2025.100858","DOIUrl":"10.1016/j.phro.2025.100858","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Although cone beam computed tomography (CBCT) enables online adaptive radiotherapy, its CT number accuracy may be insufficient for online adaptive proton therapy (OAPT). We compared proton dose distributions calculated directly on CBCT with calculations using additional CBCT image-processing methods in prostate cancer.</div></div><div><h3>Materials and methods</h3><div>Retrospective proton plans were created for 10 prostate patients originally treated with 5-fraction online adaptive photon radiotherapy using CBCT. These plans were forward-calculated on each CBCT with four different approaches: (1) the clinical CBCT with a dedicated CT number calibration, (2) CBCT with histogram correction, (3) CT deformed to the CBCT, and (4) deformed CT with an air-cavity correction. Additionally, adaptive treatment using an OAPT workflow was simulated for each fraction and compared among the four CBCT-based methods. Dose-volume histograms (DVH) and related parameters were compared between the four methods for both non-adaptive and online adaptive treatment simulations.</div></div><div><h3>Results</h3><div>Proton dose distributions were comparable across all CBCT-based strategies, with median differences of up to 1% for all DVH metrics compared to a reference method. Larger differences were observed for doses calculated directly on the CBCT for patient geometries deviating from the CBCT-specific calibration. Despite these differences, all four methods indicated the dosimetric benefits of OAPT over non-adaptive treatment.</div></div><div><h3>Conclusion</h3><div>An advanced CBCT system enables proton dose calculations performed directly on the CBCT, demonstrating sufficient accuracy for integration into an OAPT workflow. Additional CBCT-based post-processing techniques are recommended to maximize the dosimetric benefit of plan adaptation in all patient populations.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100858"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145520096","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":"Apparent diffusion coefficient as a quantitative biomarker for prostate cancer treatment response on a 1.5 Tesla magnetic resonance-linear accelerator: Impact of image registration and acquisition type","authors":"Prashant P. Nair ,&nbsp;Joan Chick ,&nbsp;Magali Nuixe ,&nbsp;Bastien Lecoeur ,&nbsp;Yu Xiao ,&nbsp;Sian Cooper ,&nbsp;Alison C. Tree ,&nbsp;Petra J. van Houdt ,&nbsp;Uwe Oelfke ,&nbsp;Andreas Wetscherek","doi":"10.1016/j.phro.2025.100851","DOIUrl":"10.1016/j.phro.2025.100851","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Diffusion-weighted magnetic resonance imaging (DW-MRI) is a quantitative biomarker for cancer detection and treatment monitoring. On magnetic resonance-linear accelerator (MR-Linac) systems, diffusion-weighted echo planar imaging (DW-EPI) suffers from geometric distortion, reducing the repeatability of apparent diffusion coefficient (ADC) measurements. This study evaluated the effect of low-distortion split acquisition of fast spin-echo signal (SPLICE) sequences, and of image registration on the repeatability coefficient (RC) of ADC.</div></div><div><h3>Materials and methods</h3><div>ADC bias, repeatability, signal-to-noise ratio (SNR) and geometric fidelity were measured in a diffusion phantom using three DW-EPI and two DW-SPLICE protocols. ADC short-term and long-term RCs were measured in healthy volunteers. In patients, the registration of DW-EPI to unweighted images (b0) was tested for its effect on RC in gross tumour volume (GTV) and non-tumour prostate (NT-P), and for its ability to detect significant ADC changes.</div></div><div><h3>Results</h3><div>Phantom experiments showed strong linear correlation with ground-truth ADC (R² &gt; 0.99). Among EPI protocols, DW-EPI-AP offered the best balance of high SNR and low RC, while Z-direction encoded DW-EPI was the most variable. Both DW-SPLICE variants exhibited reduced distortion compared with EPI but poorer repeatability. In volunteers, long-term RCs (8.0–33.7 %) varied more than short-term RCs (8.9–15.4 %). In patients, registration improved RCs (GTV: 28.0 → 25.1 %; NT-P: 19.6 → 12.6 %) and improved detection of significant ADC change in patients (GTV: 0/6 → 1/6; NT-P: 2/6 → 5/6).</div></div><div><h3>Conclusion</h3><div>RC and accuracy of DW-EPI agrees with published literature and improves after registration. DW-SPLICE shows lower geometric distortion but would require further optimization and validation to improve repeatability.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100851"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321177","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":"Detection and localization of radiation-induced pneumonitis using T2-mapping magnetic resonance imaging","authors":"Rabea Klaar ,&nbsp;Kaltra Begaj ,&nbsp;Moritz Rabe ,&nbsp;Stefanie Corradini ,&nbsp;Chukwuka Eze ,&nbsp;Claus Belka ,&nbsp;Bastian Sabel ,&nbsp;Guillaume Landry ,&nbsp;Christopher Kurz ,&nbsp;Julien Dinkel","doi":"10.1016/j.phro.2025.100878","DOIUrl":"10.1016/j.phro.2025.100878","url":null,"abstract":"&lt;div&gt;&lt;h3&gt;Background and purpose:&lt;/h3&gt;&lt;div&gt;Radiation-induced pneumonitis (RP), a complication of lung radiotherapy, occurs at the earliest 6–12 weeks post-treatment. To assess RP, repeated computed tomography (CT)-scans post-radiotherapy are standard-of-care, but increase the patients’ dose burden and secondary cancer risk. We propose a pipeline based on magnetic resonance imaging (MRI) &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;-mapping acquired 2–3 months post-radiotherapy that provides an automated patient stratification and initial segmentation of the RP lung volume.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Materials and methods:&lt;/h3&gt;&lt;div&gt;In total, 24 lung tumor patients received MRI-guided radiotherapy at a 0.35&lt;!--&gt; &lt;!--&gt;T MR-Linac. MRI &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;-maps were retrieved from &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;-weighted images acquired at a diagnostic 1.5&lt;!--&gt; &lt;!--&gt;T MRI-scanner 8–20 weeks post-radiotherapy. Mean baseline-corrected &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;-values were calculated in the planning target volume and the lung volume receiving&lt;span&gt;&lt;math&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;20&lt;!--&gt; &lt;!--&gt;Gy excluding the gross tumor volume. Their stratification potential (endpoint RP grade&lt;span&gt;&lt;math&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;1) was assessed in a univariate receiver operating characteristic curve–area under the curve (ROC–AUC) analysis using bootstrapping. Significant differences were probed (Mann–Whitney U test, &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;Stats&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;=0.05). Thresholding using the maximal Youden index was utilized for the &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;-based RP segmentation. The Dice similarity coefficient (DSC), 95% Hausdorff distance (HD95), sensitivity, precision and segmentation AUC (SegAUC) were used for the comparison with the ground-truth CT-based RP segmentation.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Results:&lt;/h3&gt;&lt;div&gt;RP grade&lt;span&gt;&lt;math&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;1 was diagnosed in 15/24 patients. The &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;-values in both regions achieved significant separation of distributions (median 13.8/2.9&lt;!--&gt; &lt;!--&gt;ms and 5.0/-2.6&lt;!--&gt; &lt;!--&gt;ms RP/non-RP) with &lt;span&gt;&lt;math&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;-values&lt;span&gt;&lt;math&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;0.05 and AUC&lt;span&gt;&lt;math&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;0.76. Moderate quantitative agreement was found between &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;-based and ground-truth segmentation (DSC=0.32, HD95=20.1&lt;!--&gt; &lt;!--&gt;mm and SegAUC=0.76).&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Conclusion:&lt;/h3&gt;&lt;div&gt;MRI &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;-values allow an automated RP patient stratification and initial ","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100878"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145681097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temporal changes in native and late gadolinium enhanced ultrashort echo time magnetic resonance imaging during gynecologic cancer radiation therapy","authors":"Khadija Sheikh ,&nbsp;Bruce L. Daniel ,&nbsp;Michael Roumeliotis ,&nbsp;Junghoon Lee ,&nbsp;Thomas Benkert ,&nbsp;Himanshu Bhat ,&nbsp;Pan Su ,&nbsp;Ravi T. Seethamraju ,&nbsp;Daniel Y. Song ,&nbsp;Akila N. Viswanathan ,&nbsp;Ehud J. Schmidt","doi":"10.1016/j.phro.2025.100883","DOIUrl":"10.1016/j.phro.2025.100883","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Radiotherapy (RT) response in gynecologic cancers varies widely and is influenced by several factors. We evaluated whether fibrosis detected with inversion-recovery ultrashort-echo-time (IR-UTE) MRI (magnetic-resonance-imaging) signal-intensity (SI) could serve as noninvasive biomarkers of treatment response in patients imaged serially during external-beam RT (EBRT) and brachytherapy (BT).</div></div><div><h3>Materials and methods</h3><div><em>Patients:</em> Fifteen patients with gynecologic cancer were included. Five participants underwent seven MRIs: pre-RT, weeks 1 (RT_wk1), 2 (RT_wk2), and 3 (RT_wk3) of EBRT, post-EBRT, 1-week post-BT, and 12 weeks post-BT. Ten participants did not receive MRI in RT_wk1, RT_wk2, or 1-week post-BT. <em>Imaging:</em> T2-weighted, diffusion-weighted images, and dynamic-contrast-enhanced MR images were acquired to segment the remnant-tumor-volume. Diffuse-fibrosis (F_Diffuse) was imaged with non-contrast dual-echo IR research application, only retaining the ultrashort-(50 µs)-echo SI. Dense-fibrosis (F_Dense) imaging utilized Late-Gadolinium-Enhanced IR-UTE, acquired ∼ 15 min post-Gadavist. <em>Analysis:</em> R2* (apparent transverse relaxation rate) maps, indicative of hypoxia, were generated using R2* MRI. The mean F_Diffuse SI, F_Dense SI, and R2* within the remnant-tumor-volume were determined and compared over the course of RT.</div></div><div><h3>Results</h3><div>Changes in F_Diffuse SI and F_Dense SI were observed after 14 Gy. Across all patients, F_Diffuse SI peaked during RT_wk2 and F_Dense SI peaked during RT_wk3. F_Dense SI was higher during RT_wk3 than pre-RT (<em>p &lt;</em> 0.05). Minor changes in F_Dense SI were observed post-BT week-12 (<em>p &gt;</em> 0.05). Remnant-tumor R2* correlated with F_Dense SI (<em>p =</em> 0.03).</div></div><div><h3>Conclusions</h3><div>The largest increase in F_Dense occurred early during EBRT. Elevated F_Dense correlated with elevated R2* in the remnant-tumor, suggesting that fibrosis is an early indicator of radiation-resistant hypoxic regions.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100883"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145681098","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":"Towards clinical implementation of T2-weighted cine imaging for intrafraction drift correction workflows on the 1.5 Tesla magnetic resonance-linear accelerator","authors":"Lieke T.C. Meijers ,&nbsp;Johannes C.J. de Boer ,&nbsp;Jochem R.M. van de Voort van Zyp ,&nbsp;Nicole G.P.M. Vissers ,&nbsp;Reijer H.A. Rutgers ,&nbsp;Eveline Alberts ,&nbsp;Jasmijn M. Westerhoff ,&nbsp;Alice M. Couwenberg ,&nbsp;Marieke I. Snijder-van As ,&nbsp;Stefano Mandija ,&nbsp;Edwin Versteeg ,&nbsp;Martijn P.W. Intven ,&nbsp;Bas W. Raaymakers ,&nbsp;Astrid L.H.M.W. van Lier","doi":"10.1016/j.phro.2025.100859","DOIUrl":"10.1016/j.phro.2025.100859","url":null,"abstract":"<div><h3>Background and purpose</h3><div>In magnetic resonance–linear accelerator (MR-Linac) treatments, balanced Turbo Field Echo (bTFE) cine imaging is used to monitor and correct intrafraction motion but provides limited contrast and is prone to artifacts. This study evaluates a T2-weighted Turbo Spin Echo (T2-TSE) cine sequence for intrafraction drift correction in pelvic targets and compares its performance with the bTFE-cine.</div></div><div><h3>Materials and methods</h3><div>During 86 fractions in 52 patients with pelvic tumors, the standard bTFE-cine and the T2-TSE-cine images were acquired interleaved coronal and sagittal on the MR-Linac. Pre- and post-treatment T2-weighted 3D images were registered. Intrafraction motion, deviations between 3D-3D and 3D-2D registration, and jitter were compared. Visual grading scores and acoustic noise levels were assessed in both sequences.</div></div><div><h3>Results</h3><div>The bTFE-cine shows in 26 cases &gt; 1 mm between the 3D-3D and 3D-2D registration compared to 6 cases for the T2-TSE-cine in all directions, however these differences were not statistically significant. The jitter was higher for the bTFE-cine in prostate cases compared to T2-TSE-cine, but comparable or less for rectum and pelvic lymph node metastatic cases. The visual assessment indicates a high preference for the T2-TSE-cine regarding target, organs at risk (OAR) visualization and in terms of artifacts. The equivalent sound levels for the bTFE-cine and T2-TSE-cine were 110.7 and 100.1 dB(A), respectively.</div></div><div><h3>Conclusion</h3><div>This study shows comparable tracking results, higher visual grading scores and lower acoustic noise levels of the T2-TSE-cine sequence over the bTFE-cine used for intrafraction drift correction workflows of pelvic targets on the MR-Linac.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100859"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466708","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":"Early response prediction during radiotherapy in rectal cancer using sequential diffusion-weighted imaging at a magnetic resonance image-guided linear accelerator","authors":"Johanna A. Hundvin ,&nbsp;Jonas Habrich ,&nbsp;Cihan Gani ,&nbsp;Jörg Assmus ,&nbsp;Inger Marie Løes ,&nbsp;Sara Pilskog ,&nbsp;Kathrine R. Redalen ,&nbsp;Daniela Thorwarth","doi":"10.1016/j.phro.2025.100846","DOIUrl":"10.1016/j.phro.2025.100846","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Varying response to chemoradiotherapy (CRT) challenges the treatment of locally advanced rectal cancer (LARC). Our purpose was to timely stratify responders by investigating the predictive potential of sequential, in-treatment diffusion-weighted (DW) magnetic resonance (MR) images.</div></div><div><h3>Materials and methods</h3><div>DW images were acquired with a 1.5 T MR-Linac at baseline and during MR-guided CRT in 15 patients with LARC prescribed long-course CRT, prospectively enrolled between 2018 and 2021. Tumour response was classified as good or poor based on pathologic tumour regression. Changes in mean tumour apparent diffusion coefficient (ADC) were analysed by linear mixed-effects models and compared to modelling using volume. Model coefficient analysis and receiver operating characteristics (ROCs) with area under the curve (AUC) were applied for timepoint investigation of response.</div></div><div><h3>Results</h3><div>Six patients had good response, with significant difference in median (range) baseline ADC; ADC_good = 1.3 (1.1–1.5) ∙ 10^-3 mm²/s, ADC_poor = 1.1 (0.9–1.4) ∙ 10^-3 mm²/s, (p = 0.03), and with greater ADC change at all evaluated timepoints. This resulted in AUCs of 0.73–0.85 and the steepest slope (m) after five fractions (m_good = 0.090, m_poor = 0.014). Combining baseline and slope improved the differentiation with AUCs of 0.90, 0.87, 0.85 and 0.83 after 5, 10, 13 or all fractions, respectively. Stratification based on volume changes was feasible after 15/25 fractions.</div></div><div><h3>Conclusions</h3><div>Early indication of treatment response in LARC was achieved by combining baseline and sequential ADC information. These encouraging results should be validated in a larger cohort.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100846"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321043","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":"Evaluation and tuning of a commercial automated planning system for prostate radiotherapy","authors":"Antony Carver,&nbsp;Stuart Green","doi":"10.1016/j.phro.2025.100834","DOIUrl":"10.1016/j.phro.2025.100834","url":null,"abstract":"<div><h3>Background and Purpose:</h3><div>Artificial Intelligence (AI) based automated planning is increasing in popularity. Guidance has been published recommending approaches for the safe implementation and monitoring of these techniques. An evaluation of a commercial AI tool was undertaken and reported along with the specific methods used to evaluate, tune and monitor the plan quality.</div></div><div><h3>Materials and Methods:</h3><div>A total of 335 previously planned prostate patients were used to evaluate and commission a commercial AI based planning solution. The quality of the automatically produced plans was compared to previous practice using models inspired by existing research into knowledge based planning. A quantile regression based technique identified the most optimal historic plans to be used for model tuning. Finally, a control chart based method was validated for post-deployment monitoring of the produced plan quality.</div></div><div><h3>Results:</h3><div>The baseline model provided by the manufacturer was found to provide good plan quality overall with 9 out 15 plan quality metrics found to have lower variance after accounting for anatomy. Rectum sparing was found to be inferior to human generated plans. Two further iterations of the model were produced in collaboration with the manufacturer. Further iterations of the model resulted in comparable rectum sparing, a 0.02 mean difference in rectum V50 Gy, was achieved whilst maintaining much of the improved consistency.</div></div><div><h3>Conclusions:</h3><div>A method to implement the guidance for commissioning of automated and AI based planning tools is presented alongside a method for monitoring the subsequent plan quality. The final plan quality achieved was comparable to or better than the original plans following two revisions.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100834"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221821","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":"First experimental demonstration of magnetic resonance-guided multileaf collimator tracking for (ultra-)hypofractionated prostate radiotherapy","authors":"Prescilla Uijtewaal ,&nbsp;Pim T.S. Borman ,&nbsp;Peter L. Woodhead ,&nbsp;Hans C.J. de Boer ,&nbsp;Bas W. Raaymakers ,&nbsp;Martin F. Fast","doi":"10.1016/j.phro.2025.100828","DOIUrl":"10.1016/j.phro.2025.100828","url":null,"abstract":"<div><h3>Background and purpose:</h3><div>(Ultra-)hypofractionated radiotherapy is an effective treatment for localized prostate cancer, but intrafraction motion can increase toxicity and/or reduce treatment efficacy. Therefore, motion management is essential. This study explores magnetic resonance imaging (MRI)-guided multileaf collimator (MLC) tracking for 2-fraction prostate radiotherapy on an MR-linac.</div></div><div><h3>Materials and methods:</h3><div>We compared two MRI-guided MLC centroid tracking workflows, each using a different motion manager to derive and stream target positions to our in-house MLC tracking software. The first workflow relies on interleaved 2D (2.5D) cine-MRI, introducing minimal latency. In contrast, the second workflow utilized 3D cine-MRI, which operates at a relatively lower imaging frequency that introduces more latency.</div><div>For experimental validation, we used a motion phantom equipped with an integrated insert that combines film with plastic scintillation dosimetry. A 2x12 Gy 11-beam prostate intensity modulated radiotherapy plan was created for tracking deliveries.</div></div><div><h3>Results:</h3><div>The signal latency introduced by the motion managers was 0.6 s for 2.5D cine-MRI and 6.3 s for 3D cine-MRI. Despite this latency, MLC tracking effectively restored the planned dose, improving the 2%/2mm local gamma pass-rates from 21% (due to linear drift) to 89% (2.5D) and 91% (3D). Plastic scintillator measurements showed reduced dose deviations at the periphery of the clinical target volume from 13–64% (no tracking) to 0–11% (2.5D) and 2–26% (3D).</div></div><div><h3>Conclusion:</h3><div>Our experiments demonstrated the technical feasibility of 2.5D and 3D cine-MRI-based MLC tracking on an MR-linac for 2-fraction prostate radiotherapy, with both motion management strategies achieving comparable dosimetric improvements despite the difference in latency.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100828"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268547","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":"Identifying the optimal time point for adaptive re-planning in prostate cancer radiotherapy to minimise rectal toxicity using normal tissue imaging biomarkers","authors":"Zhuolin Yang ,&nbsp;David J. Noble ,&nbsp;Sarah Elliot ,&nbsp;Leila Shelley ,&nbsp;Thomas Berger ,&nbsp;Raj Jena ,&nbsp;Duncan B McLaren ,&nbsp;Neil G. Burnet ,&nbsp;William H. Nailon","doi":"10.1016/j.phro.2025.100850","DOIUrl":"10.1016/j.phro.2025.100850","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Adaptive radiotherapy (ART) in prostate cancer (PCa), although not yet standard practice, is typically triggered by inter-fractional anatomical changes that emerge progressively during treatment. This study investigates whether radiomics extracted before and during treatment can identify the optimal time point for re-planning, with the goal of reducing late rectal bleeding.</div></div><div><h3>Materials and methods</h3><div>This study included 187 PCa patients from the single-centre, prospectively collected VoxTox dataset (UK-CRN-ID-13716), treated with image-guided radiotherapy using TomoTherapy and daily MVCT. Patients received either 74 Gy in 37 fractions (N = 110) or 60 Gy in 20 fractions (N = 77). Radiomic features were extracted from pre-treatment planning CTs and daily MVCTs. Grade ≥ 1 rectal bleeding was assessed at 2 years post-treatment using CTCAE v4.03. Two analysis strategies were employed: a separate analysis, where weekly features were evaluated independently; and a cumulative analysis, which progressively incorporated features from previous weeks. Logistic regression models with elastic net penalty were trained and evaluated using AUC.</div></div><div><h3>Results</h3><div>In both groups, week 1 provided the highest standalone predictive performance (test AUC = 0.766 for 74 Gy; 0.734 for 60 Gy). In the cumulative analysis, week 3 was optimal for the 74 Gy group (test AUC = 0.767), balancing performance and timing. For the 60 Gy group, week 1 remained optimal but suffered from reduced generalisability (test AUC = 0.643).</div></div><div><h3>Conclusions</h3><div>Radiomic analysis of daily imaging can support early, proactive ART in PCa, offering a personalised strategy to reduce late rectal bleeding beyond conventional anatomy-based approaches.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100850"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268549","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":"Microstructural modelling based on diffusion weighted imaging to guide dose painting in carbon ions for large sacral chordomas","authors":"Giovanni Parrella ,&nbsp;Letizia Morelli ,&nbsp;Giuseppe Magro ,&nbsp;Lars Glimelius ,&nbsp;Jakob Ödén ,&nbsp;Mario Ciocca ,&nbsp;Sara Imparato ,&nbsp;Marco Rotondi ,&nbsp;Maria Rosaria Fiore ,&nbsp;Ester Orlandi ,&nbsp;Guido Baroni ,&nbsp;Silvia Molinelli ,&nbsp;Chiara Paganelli","doi":"10.1016/j.phro.2025.100887","DOIUrl":"10.1016/j.phro.2025.100887","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Dose Painting (DP) in radiotherapy is a strategy to account for the tumor microstructural heterogeneity. This study evaluated a DP approach in carbon ion radiotherapy (CIRT), using cell count estimates derived from diffusion-weighted magnetic resonance imaging (DWI).</div></div><div><h3>Materials and methods</h3><div>Thirty-seven large sacral chordoma (SC) patients were analysed. Voxel-wise cell count was estimated from DWI using a published microstructural model. A Poisson-based tumor control probability (TCP) model, fitted on 27 patients, guided DP optimization in a research version of RayStation 2024A. The approach was tested on 10 patients, comparing uniform-dose plans against two strategies: dose redistribution (DR), which maintained the mean gross tumor volume (GTV) dose, and dose escalation (DE), which allowed a 3 % increase. Plan evaluation on targets and organs at risk (OARs) included dose-volume histogram metrics (D_95%, D_50%, D_1%) and dose-averaged linear energy transfer (LET_d)-volume histogram metrics (L_98%, L_50%, L_1%) to assess clinical acceptability. TCP gain quantified the benefit of biologically targeted strategies. TCP uncertainty was evaluated by propagating the microstructural model’s errors to generate best- and worst-case cell count maps.</div></div><div><h3>Results</h3><div>DE and DR plans met clinical acceptability criteria. DE increased TCP from 75.5 ± 5.6 % to 83.3 ± 3.9 % (p &lt; 0.001), with −3 to +5 percentage points variation under uncertainty. DR plans showed a TCP gain of 1.8 ± 1.0 percentage points. No significant dose or LET_d increase was observed in OARs, while DE plans showed a lower L_98% in GTV.</div></div><div><h3>Conclusions</h3><div>Dose painting based on microstructural modelling in CIRT showed potential to improve TCP while sparing OARs.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"36 ","pages":"Article 100887"},"PeriodicalIF":3.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145736397","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}