Introduction Evidence regarding radiation therapist (RTT)-led follow-up utilising electronic patient-reported outcomes (ePROs) in radiotherapy is scarce. This study evaluated patient and clinician compliance within a novel ePRO-integrated care pathway for prostate cancer (PCa) patients, exploring its impact on communication, involvement, and post-radiotherapy preferences regarding follow-up. Materials and methods Weekly ePROs were collected via a hospital application during treatment and up to 24 weeks post-radiotherapy. During radiotherapy, RTTs monitored acute toxicity in real-time during weekly ePRO-guided symptom reviews. Compliance was defined as ePROs completed and actively reviewed by the RTT. Patient satisfaction was evaluated using a validated Patient Feedback Form. Four weeks after radiotherapy, patients could choose a structured, RTT-led follow-up consultation. Results Of 287 enrolled patients November 2020 – March 2024, 248 (86%) completed The Patient Feedback Form. During active radiotherapy, the pooled patient ePRO response rate was 84.8% (1548/1826), and the RTT handling rate was 88.4% (1368/1548 questionnaires). Patient post-treatment response rates remained high at weeks 12 (88.7%) and 24 (82.5%). ePRO integration improved communication with RTTs (93.0%), symptom discussion (95.5%), and control over care (93.0%). Among 177 having the choice of follow-up, 73% selected RTT-led follow-up. In logistic regression models, no sociodemographic or clinical factors predicted follow-up preference, though older age showed a trend for RTT-led follow-up selection (aOR 1.05, 95% CI: 0.99–1.11, p = 0.086). Conclusions The ePRO-integrated workflow fostered an empowering clinical environment with strong patient involvement. Our findings demonstrated high patient and RTT compliance across the digital pathway in a diverse prostate cancer cohort that significantly improved patient-clinician communication with a feasible, preference-driven post-treatment follow-up.

Accurate delineation of pancreatic tumors on Magnetic Resonance Imaging (MRI) is important for diagnosis, radiotherapy treatment planning, and outcome assessment, but remains challenging due to complex anatomy and subtle tumor appearance. In routine practice, tumor contours on MRI are produced manually, which is time-consuming and subject to inter-observer variability. Radiotherapy on MRI-Linear Accelerator (MRI-Linac) systems further requires fast and consistent Gross Tumor Volume (GTV) contours for online adaptation, yet most public pancreas tumor segmentation benchmarks focus on Computed Tomography (CT). The Pancreatic Tumor Segmentation in Therapeutic and Diagnostic MRI (PANTHER) challenge addresses this gap by benchmarking automatic pancreatic tumor segmentation on MRI. The dataset includes contrast-enhanced T1-weighted diagnostic MRI and T2-weighted MRI-Linac scans with expert pancreas and tumor annotations, organized into two tasks: (1) tumor segmentation on diagnostic MRI and (2) tumor segmentation on MRI-Linac images. Performance was evaluated using overlap metrics, distance-based metrics, and tumor volume error. The challenge attracted 285 registered participants, with 12 and 9 final submissions for Tasks 1 and 2, respectively. On diagnostic MRI, top methods achieved performance close to inter-reader agreement. Multi-reader analysis suggested that models often reproduced the contouring style of the training annotator, highlighting the importance of annotation quality and consensus. In contrast, performance on MRI-Linac images was lower and more heterogeneous, including cases of complete localization failure. PANTHER provides the first public benchmark for pancreatic tumor segmentation on MRI, showing that clinically useful automation is feasible on diagnostic MRI, while robust MRI-Linac GTV segmentation remains an open challenge.

Background and purpose:Active motion management (AMM) during magnetic resonance image (MRI)-guided pancreatic cancer radioablation enables tight planning target volume (PTV) margins but may prolong treatment. AMM strategies include beam gating and drift correction, which respectively interrupt or adjust treatment delivery in response to target motion. This study evaluates gross tumor volume (GTV) dose coverage and time efficiency using varying AMM settings. Materials and methods:Cine MRI data from 100 fractions in 20 patients undergoing MRI-guided pancreatic cancer radioablation were used to simulate treatment delivery of 5 × 10.0 Gy using a 2 mm PTV margin. Seventeen scenarios were evaluated: No AMM and combinations of gating window and drift correction thresholds from 5 mm to 2 mm. Accumulated dose and treatment time efficiency (beam-on/total time) were derived from the simulated beam history. Results:Without AMM, the median (5th-95th percentile) change in GTV D98% was -1.8 (-10.3-1.6) Gy. Lowering the drift threshold to 2 mm while using a 5 mm gating window achieved almost similar GTV dose preservation to a 2 mm gating window with 5 mm drift threshold [-0.9 (-3.9-1.1) Gy vs -0.8 (-3.3-1.2) Gy), but with substantially higher efficiency [90 (69-100) % vs 60 (28-94) %]. Conclusions:AMM improved GTV dose fidelity for pancreatic cancer radioablation with tight PTV margins, but stricter motion thresholds reduced efficiency. Prioritizing a low drift threshold over a narrow gating window preserved most of dose-related benefits while maintaining more efficient delivery, and may represent an AMM strategy for clinical workflows.

PURPOSE:Stereotactic body radiation therapy (SBRT) is a local treatment option for liver metastases. The introduction of magnetic resonance imaging (MRI) guided SBRT has paved the way for optimal treatment outcomes by improving tumor visualization, daily plan adaptation and margin reduction. The purpose of this study was to review the tolerability of MRI-guided liver SBRT and to present early toxicity and quality of life (QoL) outcomes from a prospective multicenter registry. METHODS AND MATERIALS:All patients enrolled in the MOMENTUM study (NCT04075305) who were treated for liver metastases between April 2019 and April 2023 on a 1.5T MR-Linac were included. Descriptive statistics were used to present tolerability of treatment, acute toxicity (National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0) and Quality of Life questionnaires (QLQ-C30 and EQ-5D-5L) at baseline and 3 months after treatment. RESULTS:A total of 135 patients (median age, 67 years; range, 31-93) were treated in 7 institutes across 4 countries. The most common primary tumor origins were colorectal (50%) and lung cancer (12%). Prescribed total SBRT doses ranged from 20.0 to 67.5 Gy, delivered in 2 to 12 fractions of 7 to 22.5 Gy per fraction (median biologically effective dose, 180 Gy; range, 59.5-540 Gy). A total of 97% of patients (n = 131) completed their treatment, with no interruptions due to poor tolerability. Up to 3 months, 14 grade 3 toxicities were reported in 12 patients (10.6%), with only 1 (0.9%) recorded as radiation therapy related (gastritis). No grade ≥4 toxicities were reported. Sixty-two and 63 patients completed the QLQ-C30 and EQ-5D-5L questionnaires at both time points, respectively. These showed a worsening of 5 to 10 points at 3 months for role functioning, nausea, fatigue, constipation, and pain. CONCLUSIONS:In this prospective cohort, 97% of treatments were well tolerated and completed successfully, with only 1 case of acute grade 3 radiation therapy related toxicity and no grade ≥4 toxicity reported. QoL outcomes showed clinically relevant worsening (defined as ≥5 points) in 5 domains, which is comparable to that of computed tomography (CT-) guided SBRT. Overall, the outcomes showed that MRI-guided SBRT is a well-tolerated and safe treatment for patients with liver metastases.

Background and Purpose: Daily magnetic resonance image (MRI)-guided radiotherapy plan adaptation requires time-consuming manual contour edits of targets and organs at risk in the online workflow. Recent advances in auto-segmentation promise to deliver high-quality delineations within a short time frame. However, the actual time benefit in a clinical setting is unknown. The current study investigated the feasibility and time gain of implementing online artificial intelligence (AI)-based delineations at a 1.5 T MRI-Linac. Materials and methods: Fifteen consecutive prostate cancer patients, treated to 60 Gy in 20 fractions at a 1.5 T MRI-Linac, were included in the study. The first 5 patients (Group 1) were treated using the standard contouring workflow for all fractions. The last 10 patients (Group 2) were treated with the standard workflow for fractions 1 up to 3 (Group 2 - Standard) and an AI-based workflow for the remaining fractions (Group 2 - AI). AI delineations were delivered using an in-house developed AI inference service and an in-house trained nnU-Net. Results: The AI-based workflow reduced delineation time from 9.8 to 5.3 min. The variance in delineation time seemed to increase during the treatment course for Group 1, while the delineation time for the AI-based workflow was constant (Group 2 - AI). Fewer occurrences of readaptation due to target movement occurred with the AI-based workflow. Conclusion: Implementing an AI-based workflow at the 1.5 T MRI-Linac is feasible and reduces the delineation time. Lower variance in delineation duration supports a better ability to plan daily treatment schedules and avoids delays.

Background and purpose: Magnetic resonance imaging-guided radiotherapy (MRIgRT) enables precise tumour targeting through adaptive planning, which is particularly relevant for glioblastoma due to its dynamic morphology. Gadolinium-based contrast agents (GBCAs) enhance tumour visibility, but frequent use during MRIgRT raises safety concerns related to cumulative gadolinium exposure. This study investigated the feasibility of a reduced GBCA dose protocol for patients with glioblastoma undergoing MRIgRT, aiming to balance tumour conspicuity with minimisation of GBCA-related risks. Patient/material and methods: Nine patients with glioblastoma received hypo-fractionated MRI-Linac radiotherapy (10 × 3.4 Gy) with MRI performed with either full-dose, half-dose or no GBCA enhancement. Online gross tumour volume (GTV) delineation was performed by radiation oncologists, while offline GTV delineation was independently conducted by an expert neuroradiologist on GBCA-enhanced scans. Objective assessment using automatic thresholding and a structured Likert-scale evaluation were also performed. Results: During online adaptation, GTV volumes generally remained stable or increased, whereas offline expert assessments revealed a general volume reduction and systematic volume underestimation with half-dose scans (~18%). Relative delineation volume discrepancies were most pronounced in small tumours. Structured radiologist feedback reported lower confidence, tumour conspicuity and image quality in half-dose scans, particularly for small lesions. Otsu’s thresholding revealed reduced edge definition with decreasing contrast dose. No signs of GBCA retention were observed between fractions. Interpretation: Reduced-dose GBCA-protocols are feasible. Full-dose contrast is recommended at key fractions (e.g. baseline and mid-treatment) and for small tumours, with half-dose imaging reserved for selected intervals or larger tumours. This hybrid approach may balance safety and imaging precision in adaptive MRIgRT.

PURPOSE:Online adaptive magnetic resonance guided radiation therapy (MRgRT) using a hybrid magnetic resonance imaging and linear accelerator enables stereotactic ablative radiation doses to pancreatic tumors. We evaluated patient-reported quality of life (QoL) and clinician-reported toxicity in patients with pancreatic ductal adenocarcinoma after stereotactic MRgRT. METHOD:Patients with nonmetastatic pancreatic ductal adenocarcinoma treated with stereotactic MRgRT on a 1.5-Tesla magnetic resonance imaging and linear accelerator according to local standard practices between May 2019 and December 2023 were identified using the international, prospective observational Multi-OutcoMe EvaluatioN of radiation Therapy Using the MR-Linac study (MOMENTUM, NCT04075305). Patient-reported QoL and clinician-reported toxicity were assessed using the European Organization for Research and Treatment of Cancer Core Quality-of-Life Questionnaires and National Cancer Institute Common Terminology Criteria for Adverse Events at baseline, 3, 6, and 12 months of follow-up. Patients with new systemic therapy or resection were censored. Patients with disease progression were additionally censored for a sensitivity analysis. Mean difference (MD) QoL scores from baseline were estimated using a linear mixed model, which were evaluated for clinical relevance (MD ≥ 10) and statistical significance (P ≤ .05). Acute (≤3 months follow-up) and late (3-12 months follow-up) toxicity was captured if grade ≥3. RESULTS:A total of 127 patients were included from 8 centers. Treatment dose ranged from 30 to 50 Gy in 5 fractions. Functional QoL domains remained stable over time. A statistically significant and clinically relevant improvement was found for nausea and vomiting (MD -10; 95% CI, -17 to -3; P < .001), and in the sensitivity analysis for nausea and vomiting (MD -11; 95% CI -18 to -3; P < .001) and appetite (MD -14; 95% CI -28 to 0; P = .05), all at 6 months follow-up. No clinically relevant and statistically significant deterioration was found in other domains. New-onset acute and late grade 3 toxicity occurred in 2 patients and 1 patient, respectively. CONCLUSION:Stereotactic MRgRT for patients with nonmetastatic pancreatic ductal adenocarcinoma was associated with stable functioning, improved disease-related symptoms, and minimal toxicity up to 12 months after treatment.

BACKGROUND AND PURPOSE:The SOFT (Stereotactic ablative radiotherapy of infra-diaphragmatic sOFT tissue metastases) trial assesses the safety and efficacy of risk-adapted MR-guided stereotactic ablative radiotherapy (SABR) of infra-diaphragmatic soft tissue metastasis in patients with oligometastatic disease (OMD) (clinicaltrials.gov ID NCT04407897). This paper reports the one-year efficacy analysis and evaluates associations between local control (LC) and clinical and dosimetric parameters. MATERIALS AND METHODS:This investigator-initiated, multicenter, single-arm, phase 2 study recruited patients from four MR-linac centers in Denmark and the US. Patients with De novo or recurrent OMD with ≤5 metastases in ≤3 organs and patients with induced OMD or oligoprogressive disease (OPD) with ≤3 metastases were eligible. Fractionation schemes were 45-75 Gy in 3-8 fractions. RESULTS:The trial included 121 patients with 147 oligometastatic lesions, primarily in the liver (41 %), lymph nodes (35 %), or adrenal glands (14 %). The median follow-up time was 13.0 months, interquartile range (IQR) (11.7,13.7) months. The 1-year LC rate was 89 %, 95 % confidence interval (CI) (83,94 %). We did not observe any statistically significant associations between LC and clinical and dosimetric parameters. The median progression-free survival was 7.1 months, 95 % CI (6.0,9.4). One- and two-year overall survival was 82.6 %, 95 % CI (76.2 %,89.7 %), and 65.1 %, 95 % CI (56.4 %,75.3 %). Sixty-one patients (50 %) were kept off systemic therapy throughout the one-year follow-up. CONCLUSION:In our study, treatment with risk-adapted, MR-guided SABR resulted in a high one-year local control and survival rate and could keep half of the patients off systemic therapy within the first year of follow-up.

Background: Diagnostic quality MRI acquired daily for radiotherapy (RT) planning on an MR-linac allows longitudinal evaluation of the patients’ anatomy. This study investigated changes in prostate volume during MR-guided RT. The changes were assessed from manual delineations used clinically for daily online adaptation as well as automated segmentation by artificial intelligence (AI). The consistency and congruity of these two methods were evaluated. Methods: The prostate volumes were extracted from daily planning MRI scans of 45 patients receiving 60 Gy in 20 fractions. These volumes were manually edited during the online adaptive treatment planning workflow. The prostate was re-segmented retrospectively for each fraction by AI with an in-house developed nnU-net, trained on prostate cancer patients. The volume for each fraction was normalized to the volume at the patients’ 1st fraction to identify possible time trends. Results: Increased population mean prostate volume was seen both based on manual and automatic segmentation. However, based on manual delineations, the peak volume occurred at the 12th fraction at 106.8% of the initial volume, while based on automatic segmentation, the volume peaked at a mean increase 110.8% by the 5th fraction. Standard deviation of volumes for automated segmentation (5.2%) versus manual delineation (12.7%), and reduced variation between fractions from 3.6% to 2.6% indicate better consistency of the automatic segmentation. Conclusion: Automated segmentation by our locally trained nnU-net was more consistent than manual delineations performed clinically. The population mean increase in prostate volume peaked at 110.8% by the 5th fraction after reduce over the remaining treatment course.

Introduction:Frequent electronic patient-reported outcomes (ePROs) may become an important tool for monitoring outcomes in ultrahypofractionated MRgRT for prostate cancer, enabling real-time remote tracking of toxicity. By integrating weekly ePROs and health-related quality of life (HRQoL) assessments into the early prostate MRgRT workflow, this study aimed to explore real-time acute symptom trajectories and the impact on HRQoL. Methods:Two cohorts were followed: Patients receiving MRgRT for localised PCa (60Gy/20fx) or low-volume metastatic (M1) PCa (36Gy/6fx) and eligible to complete weekly ePROs and HRQoL measures (EQ-5D-5L, EORTC QLQ-C30) during and up to 24 weeks of follow-up. Linear mixed models were used to evaluate symptom changes over time. Results:Of 76 included PCa patients, 42 had localised PCa and 34 low-volume M1 PCa. The linear model revealed significant changes in urinary symptoms from treatment week one, persisting 2 weeks post-MRgRT in the 36 Gy cohort, and 3-4 weeks in the 60 Gy cohort. Bowel symptoms increased early post-treatment in both cohorts, with diarrhoea being most frequent. Clinically relevant changes in HRQoL were observed during follow-up: patients in the 60 Gy cohort showed HRQoL improvements after 12 and 24 weeks. In the 36 Gy cohort, patients reported improved self-rated Global health status/QoL and emotional functioning. Conclusion:Frequent ePROs during and after MRgRT provide critical insights into the timing, fluctuation and severity of acute toxicity, potentially missed with standard follow-up schedules. Integrating real-time ePROs into the MRgRT workflow is a feasible patient-centered method to systematically optimize the outcome assessments of MRgRT.

Background and purpose: The SOFT trial is a prospective, multicenter, phase 2 trial investigating magnetic resonance (MR)-guided stereotactic ablative radiotherapy (SABR) for abdominal, soft tissue metastases in patients with oligometastatic disease (OMD) (clinicaltrials.gov ID NCT04407897). We present the primary endpoint analysis of 1-year treatment-related toxicity (TRAE). Materials and methods: Patients with up to five oligometastases from non-hematological cancers were eligible for inclusion. A risk-adapted strategy prioritized fixed organs at risk (OAR) constraints over target coverage. Fractionation schemes were 45-67.5 Gy in 3-8 fractions. The primary endpoint was grade >= 4 TRAE within 12 months post-SABR. The association between the risk of gastrointestinal (GI) toxicity and clinical and dosimetric parameters was tested using a normal tissue complication probability model. Results: We included 121 patients with 147 oligometastatic targets, mainly located in the liver (41 %), lymph nodes (35 %), or adrenal glands (14 %). Nearly half of all targets (48 %, n = 71) were within 10 mm of a radiosensitive OAR. No grade 4 or 5 TRAEs, 3.5 % grade 3 TRAEs, and 43.7 % grade 2 TRAEs were reported within the first year of follow-up. We found a significant association between grade >= 2 GI toxicity and the parameters GI OAR D0.1cc, D1cc, and D20cc. Conclusion: In this phase II study of MR-guided SABR of oligometastases in the infra-diaphragmatic region, we found a low incidence of toxicity despite half of the lesions being within 10 mm of a radiosensitive OAR. GI OAR D0.1cc, D1cc, and D20cc were associated with grade >= 2 GI toxicity.

Background and Purpose: Application of different deformable dose accumulation (DDA) solutions makes institutional comparisons after online-adaptive magnetic resonance-guided radiotherapy (OA-MRgRT) challenging. The aim of this multi-institutional study was to analyze accuracy and agreement of DDA-implementations in OA-MRgRT. Material and Methods: One gold standard (GS) case deformed with a biomechanical-model and five clinical cases consisting of prostate (2x), cervix, liver, and lymph node cancer, treated with OA-MRgRT, were analyzed. Six centers conducted DDA using institutional implementations. Deformable image registration (DIR) and DDA results were compared using the contour metrics Dice Similarity Coefficient (DSC), surface-DSC, Hausdorff-distance (HD95%), and accumulated dose-volume histograms (DVHs) analyzed via intraclass correlation coefficient (ICC) and clinical dosimetric criteria (CDC). Results: For the GS, median DDA errors ranged from 0.0 to 2.8 Gy across contours and implementations. DIR of clinical cases resulted in DSC > 0.8 for up to 81.3% of contours and a variability of surface-DSC values depending on the implementation. Maximum HD95%=73.3 mm was found for duodenum in the liver case. Although DVH ICC > 0.90 was found after DDA for all but two contours, relevant absolute CDC differences were observed in clinical cases: Prostate I/II showed maximum differences in bladder V28Gy (10.2/7.6%), while for cervix, liver, and lymph node the highest differences were found for rectum D2cm3 (2.8 Gy), duodenum Dmax (7.1 Gy), and rectum D0.5cm3 (4.6 Gy). Conclusion: Overall, high agreement was found between the different DIR and DDA implementations. Case- and algorithm-dependent differences were observed, leading to potentially clinically relevant results. Larger studies are needed to define future DDA-guidelines.

Purpose: Stereotactic body radiotherapy (SBRT) has emerged as a promising new modality for locally advanced pancreatic cancer (LAPC). The current study evaluated the efficacy and toxicity of SBRT in patients with LAPC (NCT03648632). Methods: This prospective single institution phase II study recruited patients with histologically or cytologically proven adenocarcinoma of the pancreas after more than two months of combination chemotherapy with no sign of progressive disease. Patients were prescribed 50-60 Gy in 5-8 fractions. Patients were initially treated on a standard linac (n = 4). Since 2019, patients were treated using online magnetic resonance (MR) image-guidance on a 1.5 T MRI-linac, where the treatment plan was adapted to the anatomy of the day. The primary endpoint was resection rate. Results: Twenty-eight patients were enrolled between August 2018 and March 2022. All patients had nonresectable disease at time of diagnosis. Median follow-up from inclusion was 28.3 months (95 % CI 24.0-NR). Median progression-free and overall survival from inclusion were 7.8 months (95 % CI 5.0-14.8) and 16.5 months (95 % CI 10.7-22.6), respectively. Six patients experienced grade III treatment-related adverse events (jaundice, nausea, vomiting and/or constipation). One of the initial four patients receiving treatment on a standard linac experienced a grade IV perforation of the duodenum. Six patients (21 %) underwent resection. A further one patient was offered resection but declined. Conclusion: This study demonstrates that SBRT in patients with LAPC was associated with promising overall survival and resection rates. Furthermore, SBRT was safe and well tolerated, with limited severe toxicities.

Objective. The apparent diffusion coefficient (ADC) extracted from diffusion-weighted magnetic resonance imaging (DWI) is a potential biomarker in radiotherapy (RT). DWI is often implemented with an echo-planar imaging (EPI) read-out due to speed, but unfortunately low geometric accuracy follows. This study aimed to investigate the influence of geometric distortions on the ADCs extracted from the gross tumor volume (GTV) and on the shape of the GTV in abdominal EPI-DWI.Approach. Twenty-one patients had EPI-DWI scans on a 1.5 T MRI sim before treatment and on a 1.5 T MRI-Linac at one of the first treatment fractions. Off-resonance correction with and without eddy current correction were applied to ADC maps. The clinical GTVs were deformed based on the same (but inverted) corrections to assess the local-regional geometric influence of distortions. Mean surface distance (MSD), Hausdorff distance (HD), and Dice similarity coefficient (DSC) were calculated to compare the original and distorted GTVs, and ADC values were calculated based on a mono-exponential model. Phantom measurements were performed to validate the applied correction method.Main results. The median (range) ADC change within the GTV after full distortion correction was 1.3% (0.02%-6.9%) for MRI-Sim and 1.5% (0.1%-6.4%) for MRI-Linac. The additional effect of the eddy current correction was small in both systems. The median (range) MSD, HD, and DSC comparing the original and off-resonance distorted GTVs for all patients were 0.43 mm (0.11-0.94 mm), 4.00 mm (1.00-7.81 mm) and 0.93 (0.82-0.99), respectively.Significance. Overall effect of distortion correction was small in terms of derived ADC values, indicating that distortion correction is unimportant for prediction of outcomes based on ADC. However, large local geometric changes occurred after off-resonance distortion correction for some patients, suggesting that if the spatial information from ADC maps is to be used for dose painting strategies, corrections should be applied.