Physics and Imaging in Radiation Oncology最新文献

{"title":"Computed tomography-based prediction of early recurrence risks with estimating individual times to recurrence for lung cancer patients prior to radiotherapy","authors":"Takumi Kodama,&nbsp;Hidetaka Arimura,&nbsp;Yuko Shirakawa,&nbsp;Yagiz Yedekci,&nbsp;Hidetake Yabuuchi,&nbsp;Yu Jin,&nbsp;Noriyuki Nagami,&nbsp;Tadamasa Yoshitake,&nbsp;Yoshiyuki Shioyama,&nbsp;Pervin Hurmuz","doi":"10.1016/j.phro.2026.101021","DOIUrl":"10.1016/j.phro.2026.101021","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Current radiomics approaches have limitations in predicting recurrence with the time gap between radiomic features prior to treatment and individual recurrence risks following treatment. This study aimed to develop computed tomography (CT)-based prediction models of early recurrence risks by estimating individual times to recurrence (TTRs) in patients with non-small cell lung cancer (NSCLC) prior to stereotactic ablative radiotherapy (SABR).</div></div><div><h3>Materials and methods</h3><div>A total of 143 patients with stage I-II NSCLC treated with SABR were enrolled. Planning CT images were used to construct internal (<em>n</em> = 125; 43 recurrent, 56 censored, and 26 recurrence-free within 5 years) and external (<em>n</em> = 18; 15 recurrent and 3 recurrence-free) datasets. Reference TTR data from 124 recurrent patients were used to estimate virtual TTRs of 56 censored patients using a Bayesian approach with the Markov chain Monte Carlo algorithm. Three types of regression models were developed to estimate the TTR based on significant CT image features associated with early recurrences. The predictions of 1-year and 2-year recurrences based on the estimated TTRs were evaluated using the areas under the receiver operating characteristic curves (AUCs).</div></div><div><h3>Results</h3><div>The best prediction models achieved AUCs of 0.926 and 0.763 for 1-year and 0.869 and 0.883 for 2-year recurrence in the internal and external tests, respectively.</div></div><div><h3>Conclusion</h3><div>The proposed CT-based model demonstrated improved performance for predicting 1- and 2-year recurrences by directly predicting TTRs. This study could bridge the time gap between pretreatment radiomic features and individual recurrence risks.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101021"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13324663/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148377624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Helium pencil beam commissioning and beam modeling","authors":"Lukas Martin,&nbsp;Barbara Knäusl,&nbsp;Peter Kuess,&nbsp;Dietmar Georg,&nbsp;Hugo Palmans,&nbsp;Lorenz Wolf,&nbsp;Nadia Gambino,&nbsp;Fabio Farinon,&nbsp;Andrej Prochazka,&nbsp;Mansure Schafasand,&nbsp;Lars Glimelius,&nbsp;Walter Ikegami Andersson,&nbsp;Daniel Simon Colomar,&nbsp;Antonio Carlino,&nbsp;Markus Stock,&nbsp;Hermann Fuchs","doi":"10.1016/j.phro.2026.101046","DOIUrl":"10.1016/j.phro.2026.101046","url":null,"abstract":"<div><h3>Background and Purpose:</h3><div>Helium ions combine reduced lateral scattering compared to protons and a lower fragmentation tail than carbon ions, enabling sharp dose gradients and improved normal tissue sparing. This study reports the commissioning of a scanned helium pencil beam line and validation of its corresponding beam model.</div></div><div><h3>Materials and Methods:</h3><div>Synchrotron-based helium ion beams were commissioned covering energies from 54.6 to 402.8<!--> <!-->MeV/u. Depth–dose curves were measured and absolute dose calibration was performed. Beam optics (spot size, position, and intraspill stability) were evaluated for various spill lengths. A beam model was implemented in the RayStation treatment planning system (TPS) and validated through 2D absolute dose measurements in homogeneous and heterogeneous phantoms and 3D measurements of cubic spread-out Bragg peak fields. Gamma-index analysis and Monte Carlo (MC) simulations with GATE/Geant4 were performed for benchmarking.</div></div><div><h3>Results:</h3><div>Measured ranges agreed with MC simulations within <span><math><mo>±</mo></math></span>0.3<!--> <!-->mm. Spot sizes decreased with energy, independently of the spill length. Spot positions remained within <span><math><mo>±</mo></math></span>0.5<!--> <!-->mm and intraspill variations were <span><math><mo>≤</mo></math></span>0.2<!--> <!-->mm (position) and <span><math><mo>≤</mo></math></span>5.4<!--> <!-->% (size). TPS-predicted doses agreed within 0.1<!--> <!-->%. For 3D validations in homogeneous phantoms, the dose differences were generally within 2<!--> <!-->%. Median gamma pass rates exceeded 90<!--> <!-->% for 3<!--> <!-->%/1.5<!--> <!-->mm and 95<!--> <!-->% for 5<!--> <!-->%/1.5<!--> <!-->mm. For the heterogeneous phantom, differences were within -3.2<!--> <!-->%.</div></div><div><h3>Conclusions:</h3><div>Stable scanned beam delivery with helium ions was established. Validation demonstrated strong agreement between measurements, TPS calculations, and MC simulations, supporting research and future clinical application.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101046"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148658301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monte Carlo-based characterization of proton minibeam radiation therapy across clinically relevant beam parameters","authors":"Angela Corvino,&nbsp;Tim Schneider,&nbsp;Yolanda Prezado","doi":"10.1016/j.phro.2026.101032","DOIUrl":"10.1016/j.phro.2026.101032","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Proton minibeam radiotherapy (pMBRT) uses a 1D array of narrow beams to widen the therapeutic window of difficult-to-treat tumors. With the aim of identifying tumor locations that could benefit most from pMBRT, we evaluated how irradiation parameters shape 3D dose distributions.</div></div><div><h3>Materials and methods</h3><div>Monte Carlo simulations were used to compute dose distributions in water for different proton energies, beam widths (bw<em>s</em>) and center-to-center distances (ctc<em>s</em>). Optimal parameter combinations were selected according to three criteria: (i) minimization of the bw in normal tissue; (ii) maximization of the valley dose in the target; and (iii) minimization of the peak dose in normal tissue.</div></div><div><h3>Results</h3><div>For shallow tumors (≤ 2 cm), 0.5 mm beams with ctc = 3bw kept normal-tissue widths &lt; 1 mm with Bragg-peak-to-entrance dose ratio (BEDR) &gt; 1. For intermediate and deep-seated tumors (8–20 cm), 1.0–1.5 mm beams with ctc = 4–5bw kept normal-tissue widths &lt; 7 mm with peak-to-valley dose ratio (PVDR) &gt; 3 and achieved lateral dose homogeneity in the target. For very deep-seated tumors (&gt; 20 cm), 2 mm beams with ctc = 4bw maintained normal-tissue widths &lt; 10 mm with PVDR &gt; 3 at the cost of BEDR ∼ 0.5.</div></div><div><h3>Conclusion</h3><div>pMBRT may offer advantages over conventional proton therapy and GRID therapy for treating shallow and deep-seated tumors. For very deep-seated tumors (&gt; 20 cm), feasibility will depend on tumor size and proximity of organs at risk.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101032"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148738744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Systematic gravity-induced posterior tumour drift in free-breathing lung stereotactic ablative radiotherapy","authors":"Lars Merring-Mikkelsen,&nbsp;Hella M.B. Sand,&nbsp;Mads H. Brincker","doi":"10.1016/j.phro.2026.101030","DOIUrl":"10.1016/j.phro.2026.101030","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Intra-fractional respiratory tumour motion is a known challenge in lung stereotactic ablative radiotherapy (SABR), as it can compromise target dose coverage. Gravity-induced tumour baseline drift during free-breathing carries the same risk but remains uncharacterised. This study aimed to quantify posterior tumour drift in peripheral lung SABR, investigate predictive factors, and evaluate tumour dose coverage.</div></div><div><h3>Materials and methods</h3><div>In total, 97 patients (102 tumours) treated with 67.5 Gy in 3 fractions were analysed. Pre- and post-treatment cone beam computed tomography (CBCT) imaging quantified intra-fractional shifts at the first and second fraction. Temporal linear regression determined patient-specific drift rates. Correlations between drift rates and patient and tumour parameters were assessed. Plans were recalculated for worst-case drifts exceeding the 4 mm posterior planning target volume (PTV) margin.</div></div><div><h3>Results</h3><div>Systematic posterior drift was observed, with mean vertical shifts of −1.45 mm at the first fraction and − 1.24 mm at the second fraction (both <em>p</em> &lt; 0.001). Mean lateral and longitudinal shifts were negligible. No correlations with patient or tumour characteristics were identified. Based on drift rates, 15.7% of patients would exceed the 4 mm posterior margin within a 20-min treatment. Recalculated plans revealed severe gross tumour volume (GTV) underdosage: mean D_90% coverage decreased from 99.9% to 74.2% (<em>p</em> &lt; 0.001) under worst-case scenarios.</div></div><div><h3>Conclusions</h3><div>Gravity-induced posterior drift represents a systematic, clinically significant phenomenon in free-breathing lung SABR. In 15.7% of patients, drifts exceeded planning margins, with potentially severe target underdosage. Routine post-treatment CBCT verification is recommended to identify at-risk patients, enabling intervention at subsequent fractions to ensure treatment accuracy.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101030"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148478229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Breathing-phase selection for gated proton therapy in lung cancer towards temporally targeted ultra-high dose rate delivery","authors":"Simone N. Visser,&nbsp;Krista C.J. van Doorn-Wink,&nbsp;Koen F. Crama,&nbsp;Coen R.N. Rasch,&nbsp;Steven J.M. Habraken","doi":"10.1016/j.phro.2026.101065","DOIUrl":"10.1016/j.phro.2026.101065","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Ultra-high dose rate (UHDR) irradiation has been demonstrated to reduce normal tissue damage compared to conventional dose rates, while maintaining tumor response (FLASH-effect). UHDR could potentially freeze intra-fraction breathing motion, enabling margin reduction for moving tumors when accurately timed. Targeting the optimal breathing-phase could reduce organ-at-risk (OAR) dose and side effects. In this treatment planning study, the optimal phase(s) for UHDR proton therapy were identified and potential benefits were evaluated.</div></div><div><h3>Materials and methods</h3><div>Twenty lung cancer patients, previously treated with 66 GyE/24 or 60 GyE/30 fractions, were included. Four-dimensional computed tomography (4D-CT) scans with clinical target and OAR delineations were used to create new treatment plans for individual 4D-CT phases, one-phase plans (OPP) and multiple-phase plans (MPP). Clinically relevant dose-volume parameters and normal tissue complication probabilities (NTCP) were evaluated.</div></div><div><h3>Results</h3><div>Phase-targeted proton therapy (PTPT) significantly reduced OAR dose. The largest reductions were achieved with OPP, while MPP showed smaller reductions. With OPP, mean lung dose (mean: −0.7 GyE, range: −1.7 to 0.3 GyE), mean heart dose (mean: −0.4 GyE, range: −1.4 to 0.5 GyE), and mean esophagus dose (mean: −0.9 GyE, range: −6.0 to 0 GyE) were reduced, with most reductions in the 0%, 40%, and 70% phases, respectively. NTCP values indicated reduced complication probabilities across all phases, with additional gains for optimal phases.</div></div><div><h3>Conclusions</h3><div>With PTPT, OAR dose may be reduced with potential clinical benefit across all phases. The optimal phase depended on the endpoint, suggesting patient-specific phase targeting could further improve outcomes. Future research should address phase targetability, residual variation and required robustness.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101065"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148854455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In vivo dosimetry using an electronic portal imaging device for pediatric myeloablative Total body irradiation with volumetric modulated arc therapy","authors":"Francesca Greco,&nbsp;Matteo Galetto,&nbsp;Maria Vaccaro,&nbsp;Marco De Spirito,&nbsp;Andrea Fidanzio,&nbsp;Elisa Placidi,&nbsp;Enrico Rosa,&nbsp;Gerardina Stimato,&nbsp;Stefania Teodoli,&nbsp;Silvia Mariani,&nbsp;Nicola Dinapoli,&nbsp;Vincenzo Frascino,&nbsp;Maria Antonietta Gambacorta,&nbsp;Silvia Chiesa,&nbsp;Elisa Meldolesi","doi":"10.1016/j.phro.2026.101025","DOIUrl":"10.1016/j.phro.2026.101025","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Volumetric Modulated Arc Therapy (VMAT) has enabled highly conformal Total Body Irradiation (TBI), improving dose homogeneity and sparing of organs-of-interest. However, the increased complexity of VMAT-based TBI requires robust quality assurance strategies. This study evaluated the feasibility, accuracy, and reproducibility of Electronic Portal Imaging Device (EPID)-based in-vivo dosimetry (IVD) for VMAT TBI treatments.</div></div><div><h3>Materials and Methods</h3><div>Forty pediatric patients treated with VMAT-based TBI were retrospectively analyzed with two prescription schemes: 12 Gy/six fractions and 9.99 Gy/three fractions. EPID transmission images were acquired during each VMAT arc and analyzed using a gamma passing rate (Pγ) of 5%/2 mm, 10% threshold. IVD was evaluated across different anatomical regions. The impact of inter-fraction anatomical variations (weight loss, abdominal swelling, gastrointestinal air) was assessed through dose recalculations on modified CT datasets. Phantom measurements were performed to validate the sensitivity of EPID-based IVD to clinically relevant perturbations.</div></div><div><h3>Results</h3><div>IVD measurements showed median Pγ of 97.3 ± 3.2%. Across the forty patients, a mean Pγ of 99.3 ± 0.8% and 99.0 ± 0.4% was observed in the head and thoracic regions respectively, lower values (96.5 ± 3.4% and 94.3 ± 3.6%) were found in the lumbar and pelvic regions respectively. Simulated abdominal swelling ≥1.5 cm reduced target coverage, while weight loss and gastrointestinal air had limited dosimetric impact. Phantom tests confirmed IVD sensitivity to significant anatomical changes.</div></div><div><h3>Conclusions</h3><div>EPID-based IVD was a feasible tool for verifying VMAT-based TBI, enabling detection of clinically relevant inter-fraction anatomical variations and supporting safe treatment delivery.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101025"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13331980/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148391983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Feasibility of in-vivo 4D prompt-gamma treatment verification in proton therapy for pancreatic cancer","authors":"Jonathan Berthold,&nbsp;Lena Nenoff,&nbsp;Stefanie Bertschi,&nbsp;Julia Thiele,&nbsp;Fabian Lohaus,&nbsp;Guillaume Janssens,&nbsp;Julien Smeets,&nbsp;Kristin Stützer,&nbsp;Christian Richter","doi":"10.1016/j.phro.2026.101027","DOIUrl":"10.1016/j.phro.2026.101027","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Prompt-gamma imaging (PGI) can detect deviations between planned and delivered proton spots. To date, PGI has been limited to body sites not influenced by regular motion or substantial intrafraction anatomical changes that can affect the proton range during treatment delivery. This study investigates the feasibility of time-resolved (4D) PGI treatment verification with a PGI slit camera, incorporating breathing motion in a first patient application.</div></div><div><h3>Material and methods</h3><div>Synchronously acquired beam delivery (log files), breathing phase and PGI data are evaluated in 3D and 4D for four fractions with control CTs of a pancreatic cancer patient.</div></div><div><h3>Results</h3><div>The first 4D PGI workflow was developed. The median range shifts between control CT-based simulation and PGI measurements were &lt; 2.3 mm. Planning-CT-based interfraction PGI evaluations showed good agreement between planned and delivered spots for early fractions (median shift &lt; 2.1 mm), but larger deviations (median shift ∼ 6 mm) for later fractions, related to progressive patient weight loss visible on the control CTs. Differences between 3D and 4D PGI were small, due to breathing suppression applied as part of the standard clinical protocol.</div></div><div><h3>Conclusions</h3><div>A 4D PGI workflow has been successfully developed and tested on a pancreatic-cancer patient, demonstrating the feasibility of PGI-based treatment verification for patients with tumors affected by respiratory motion, even though the proof-of-concept measurements were done with breathing suppression.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101027"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13355200/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148424929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Translational barriers to digital twins in radiation oncology","authors":"Federico Mastroleo,&nbsp;Mariana Borras-Osorio,&nbsp;Shiv P. Patel,&nbsp;David M. Routman,&nbsp;Doug J. Moseley,&nbsp;Satomi Shiraishi,&nbsp;Andrew Y.K. Foong,&nbsp;Mark R. Waddle","doi":"10.1016/j.phro.2026.101024","DOIUrl":"10.1016/j.phro.2026.101024","url":null,"abstract":"<div><div>Digital twin research in radiation oncology has expanded rapidly across multiple domains, yet the field lacks definitional consensus and validated translational frameworks. A systematic search (PubMed, Scopus and Web of Science – September 2025) identified 903 records and six original studies met inclusion criteria. Appraisal of the available original studies revealed three recurring translational barriers: misuse of the term “digital twin” for virtual humans or patient-specific predictive models; overreliance on internal or in-silico validation; and limited benchmarking against clinically established alternatives. Progress toward clinical translation requires disciplined nomenclature, real-patient external validation, head-to-head benchmarking, explicit attention to data-pipeline and regulatory pathways.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101024"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13355216/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148424958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Repeatability and reproducibility of MRI-derived radiomics on a 0.35 T MR-Linac using a tissue-mimicking phantom","authors":"Florian Collard,&nbsp;Fanny Herault,&nbsp;Ludovic Vanquin,&nbsp;Anne-Laure Gagez,&nbsp;Alain Loussert,&nbsp;Dominique Collard,&nbsp;David Pasquier","doi":"10.1016/j.phro.2026.101035","DOIUrl":"10.1016/j.phro.2026.101035","url":null,"abstract":"<div><h3>Background and purpose</h3><div>Magnetic resonance–guided radiotherapy provides real-time soft-tissue–based targeting during dose delivery. Beyond image guidance, magnetic resonance linear accelerator (MR-Linac) systems offer new opportunities for developing magnetic resonance imaging (MRI)-derived radiomics biomarkers. However, the reproducibility of these biomarkers in a low-field MR-Linac environment remains unclear.</div></div><div><h3>Materials and methods</h3><div>This study evaluated the repeatability and reproducibility of MRI-derived radiomic features acquired on a 0.35 T MR-Linac using a tissue-mimicking phantom containing multiple tissue-equivalent materials. Fifty balanced steady-state free precession acquisitions were performed over 10 sessions, enabling both intra- and inter-session analyses. Forty-eight preprocessing pipelines combining normalization, discretization, and bias-field correction were assessed using the coefficient of variation and intraclass correlation coefficient for 68 radiomic features across 12 defined regions of interest.</div></div><div><h3>Results</h3><div>The combination of N4 bias correction and z-score normalization yielded the highest overall stability, with several first-order (e.g. Entropy, Mean) and texture-based (e.g. glcm_DifferenceEntropy and glrlm_ShortRunEmphasis) features showing a coefficient of variation &lt;5% and/or an intraclass correlation coefficient (2,1) &gt; 0.85 across phantom materials. Stability varied with phantom composition, with higher reproducibility in homogeneous PVP-40 and water inserts compared to fat or fibroglandular compartments. Comparison with previous 0.35 T MR-Linac studies identified a consistent subset of robust features, supporting their potential as standardized MRI-derived radiomic biomarkers.</div></div><div><h3>Conclusions</h3><div>These findings demonstrated the critical role of preprocessing and tissue composition in feature reproducibility and highlighted the importance of tissue-mimicking phantoms for validating MR-Linac-based quantitative imaging pipelines.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101035"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148477866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a cost-effective end-to-end commissioning test for simulation-omitted direct-to-unit adaptive radiotherapy","authors":"Da Wang,&nbsp;Justin Visak,&nbsp;Sean Domal,&nbsp;Zhisheng Tong,&nbsp;Viktor Iakovenko,&nbsp;Tsuicheng Chiu,&nbsp;Andrew Godley,&nbsp;David Parsons,&nbsp;Mu-Han Lin","doi":"10.1016/j.phro.2026.101028","DOIUrl":"10.1016/j.phro.2026.101028","url":null,"abstract":"<div><h3>Background and Purpose</h3><div>Direct-to-Unit (simulation-omitted) adaptive radiotherapy (ART) enables same-day treatment by generating treatment plans from diagnostic images, eliminating the need for computed tomography (CT) simulation. These workflows rely on online plan re-optimization to account for anatomical, CT-number, and setup variations. However, no standardized end-to-end (E2E) credentialing protocol currently exists to validate the accuracy of Direct-to-Unit ART. Although customized ART phantoms are available, they are often costly, and impractical for one-time commissioning. To address this gap, we developed a low-cost E2E commissioning framework using a commercially available CIRS ZEUS phantom to verify workflow accuracy while minimizing financial burden.</div></div><div><h3>Materials and Methods</h3><div>E2E commissioning tests were performed on Varian Ethos and Elekta Unity systems using a CIRS ZEUS phantom (Model 008Z) equipped with inserts for ionization chamber point-dose and planar film measurements. The ionization chamber and Gafchromic EBT4 films were independently cross-calibrated on an Elekta Versa linear accelerator. Pseudo–diagnostic CT datasets were generated and deformed to simulate anatomical variation. Pre-plans (2 Gy × 30 fractions) were created and delivered across three ART fractionation schemes. Point-dose measurements were compared with system-reported values, and planar dose distributions were evaluated using global gamma analysis.</div></div><div><h3>Results</h3><div>All point-dose differences were within 3% (for high-dose regions) or 3 cGy (for low-dose regions) of the system-reported values. All planar film measurements achieved gamma pass rates exceeding 90% using 3%/3 mm criterion.</div></div><div><h3>Conclusion</h3><div>This cost-effective E2E approach provides a practical commissioning solution for Direct-to-Unit ART, supporting safe clinical implementation and facilitating cross-institutional standardization.</div></div>","PeriodicalId":36850,"journal":{"name":"Physics and Imaging in Radiation Oncology","volume":"40 ","pages":"Article 101028"},"PeriodicalIF":3.2,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148477915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}