Studies have demonstrated the potential of online adaptive radiotherapy (oART). However, routine use has been limited due to resource demanding solutions. This study reports on experiences with oART ...in the pelvic region using a novel cone-beam computed tomography (CBCT)-based, artificial intelligence (AI)-driven solution.
Automated pre-treatment planning for thirty-nine pelvic cases (bladder, rectum, anal, and prostate), and one hundred oART simulations were conducted in a pre-clinical release of Ethos (Varian Medical Systems, Palo Alto, CA). Plan quality, AI-segmentation accuracy, oART feasibility and an integrated calculation-based quality assurance solution were evaluated. Experiences from the first five clinical oART patients (three bladder, one rectum and one sarcoma) are reported.
Auto-generated pre-treatment plans demonstrated similar planning target volume (PTV) coverage and organs at risk doses, compared to institution reference. More than 75% of AI-segmentations during simulated oART required none or minor editing and the adapted plan was superior in 88% of cases. Limitations in AI-segmentation correlated to cases where AI model training was lacking. The five first treated patients complied well with the median adaptive procedure duration of 17.6 min (from CBCT acceptance to treatment delivery start). The treated bladder patients demonstrated a 42% median primary PTV reduction, indicating a 24%-30% reduction in V45Gy to the bowel cavity, compared to non-ART.
A novel commercial oART solution was demonstrated feasible for various pelvic sites. Clinically acceptable AI-segmentation and auto-planning enabled adaptation within reasonable timeslots. Possibilities for reduced PTVs observed for bladder cancer indicated potential for toxicity reductions.
Chemo-radiotherapy with curative intent for anal cancer has high complete remission rates, but acute treatment-related gastrointestinal (GI) toxicity is significant. Toxicity occurs due to ...irradiation of surrounding normal tissue. Current radiotherapy requires the addition of large planning margins to the radiation field to ensure target coverage regardless of the considerable organ motion in the pelvic region. This increases the irradiated volume and radiation dose to the surrounding normal tissue and thereby toxicity. Online adaptive radiotherapy uses artificial intelligence to adjust the treatment to the anatomy of the day. This allows for the reduction of planning margins, minimizing the irradiated volume and thereby radiation to the surrounding normal tissue.This study examines if cone beam computed tomography (CBCT)-guided oART with daily automated treatment re-planning can reduce acute gastrointestinal toxicity in patients with anal cancer.
The study is a prospective, single-arm, phase II trial conducted at Copenhagen University Hospital, Herlev and Gentofte, Denmark. 205 patients with local only or locally advanced anal cancer, referred for radiotherapy with or without chemotherapy with curative intent, are planned for inclusion. Toxicity and quality of life are reported with Common Terminology Criteria of Adverse Events and patient-reported outcome questionnaires, before, during, and after treatment. The primary endpoint is a reduction in the incidence of acute treatment-related grade ≥ 2 diarrhea from 36 to 25% after daily online adaptive radiotherapy compared to standard radiotherapy. Secondary endpoints include all acute and late toxicity, overall survival, and reduction in treatment interruptions.
Accrual began in January 2022 and is expected to finish in January 2026. Primary endpoint results are expected to be available in April 2026.
This is the first study utilizing online adaptive radiotherapy to treat anal cancer. We hope to determine whether there is a clinical benefit for the patients, with significant reductions in acute GI toxicity without compromising treatment efficacy.
ClinicalTrials.gov Identifier: NCT05438836. Danish Ethical Committee: H-21028093.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Purpose
The purpose of this study was to evaluate our 2 years’ experience with single-isocenter, non-coplanar, volumetric modulated arc therapy (VMAT) for brain metastasis (BM) stereotactic ...radiosurgery (SRS).
Methods
A total of 202 patients treated with the VMAT SRS solution were analyzed retrospectively. Plan quality was assessed for 5 mm (120) and 2.5 mm (high-definition, HD) central leaf width multileaf collimators (MLCs). For BMs at varying distances from the plan isocenter, the geometric offset from the ideal position for two image-guided radiotherapy workflows was calculated. In the workflow with ExacTrac (BrainLAB, München, Germany; W‑ET), patient positioning errors were corrected at each couch rotation. In the workflow without ExacTrac (W-noET), only the initial patient setup correction was considered. The dose variation due to rotational errors was simulated for multiple-BM plans with the HD-MLC.
Results
Plan conformity and quality assurance were equivalent for plans delivered with the two MLCs while the HD-MLC plans provided better healthy brain tissue (BmP) sparing. 95% of the BMs had residual intrafractional setup errors ≤ 2 mm for W‑ET and 68% for W‑noET. For small BM (≤1 cc) situated >3 cm from the plan isocenter, the dose received by 95% of the BM decreased in median (interquartile range) by 6.3% (2.8–8.8%) for a 1-degree rotational error.
Conclusion
This study indicates that the HD-MLC is advantageous compared to the 120-MLC for sparing healthy brain tissue. When a 2-mm margin is applied, W‑noET is sufficient to ensure coverage of BM situated ≤ 3 cm of the plan isocenter, while for BM further away, W‑ET is recommended.
•Automated treatment planning system compared to manual planning.•Equivalent plan quality between VMAT manually generated- and IMRT automatically generated plans.•Evaluation of anal, prostate and ...rectum treatment plans.•Generation of highly consistent IMRT automated plan within 2 to 3.5 min.
The Ethos system has enabled online adaptive radiotherapy (oART) by implementing an automated treatment planning system (aTPS) for both intensity-modulated radiotherapy (IMRT) and volumetric modulated arc radiotherapy (VMAT) plan creation. The purpose of this study is to evaluate the quality of aTPS plans in the pelvic region.
Sixty patients with anal (n = 20), rectal (n = 20) or prostate (n = 20) cancer were retrospectively re-planned with the aTPS. Three IMRT (7-, 9- and 12-field) and two VMAT (2 and 3 arc) automatically generated plans (APs) were created per patient. The duration of the automated plan generation was registered. The best IMRT-AP and VMAT-AP for each patient were selected based on target coverage and dose to organs at risk (OARs). The AP quality was analyzed and compared to corresponding clinically accepted and manually generated VMAT plans (MPs) using several clinically relevant dose metrics. Calculation-based pre-treatment plan quality assurance (QA) was performed for all plans.
The median total duration to generate the five APs with the aTPS was 55 min, 39 min and 35 min for anal, prostate and rectal plans, respectively. The target coverage and the OAR sparing were equivalent for IMRT-APs and VMAT-MPs, while VMAT-Aps.
demonstrated lower target dose homogeneity and higher dose to some OARs. Both conformity and homogeneity index were equivalent (rectal) or better (anal and prostate) for IMRT-APs compared to VMAT-MPs. All plans passed the patient-specific QA tolerance limit.
The aTPS generates plans comparable to MPs within a short time-frame which is highly relevant for oART treatments.
•Online adaptive radiotherapy (oART) of anal cancer enabled PTV margin reductions.•oART reduced critical dose-volume parameters of bowel bag and bladder.•Rigid propagation was necessary for an ...efficient and safe oART workflow.•CBCT-guided oART was feasible for patients with anal cancer.
Online adaptive radiotherapy (oART) potentially spares OARs as PTV margins are reduced. This study evaluates dosimetric benefits, compared to standard non-adaptive radiotherapy (non-ART), target propagation methods, and first clinical treatments of CBCT-guided oART of anal cancer.
Treatment plans with standard non-ART and reduced oART PTV margins were retrospectively generated for 23 consecutive patients with anal cancer. For five patients randomly selected among the 23 patients, weekly CBCT-guided oART sessions were simulated, where the targets were either deformed or rigidly propagated. Preferred target propagation method and dose to OARs were evaluated. Ten consecutive patients with anal cancer were treated with CBCT-guided oART. Target propagation methods and oART procedure time were evaluated.
For the retrospective treatment plans, oART resulted in median reductions in bowel bag V45Gy of 11.4 % and bladder V35Gy of 16.1%. Corresponding values for the simulated sessions were 7.5% and 27.1%. In the simulated sessions, 35% of all targets were deformed while 65% were rigidly propagated. Manual editing and rigid propagation were necessary to obtain acceptable target coverage. In the clinical treatments, the primary and some elective targets were rigidly propagated, while other targets were deformed. The median oART procedure time, measured from CBCT acquisition to completion of plan review and QA, was 23 min.
Simulated oART reduced the dose to OARs, indicating potential reduction in toxicity. Rigid propagation of targets was necessary to reduce the need for manual edit. Clinical treatments demonstrated that oART of anal cancer is feasible but time-consuming.
•CBCT-guided oART was feasible for patients with bladder cancer.•A novel solution with AI fostered a time-efficient oART procedure.•oART with patient-specific margins enabled large PTV-T ...reductions.•Conducting oART reduced critical dose-volume parameters of bowel bag and rectum.
Online adaptive radiotherapy (oART) potentially reduces the dose to organs at risk (OARs) as the planning target volume (PTV) margins are reduced compared to a non-adaptive approach (non-ART). This study evaluates the feasibility and dosimetric impact of cone-beam computed tomography (CBCT)-guided oART of urinary bladder cancer for the first patients treated, using patient-specific margins.
Sixteen consecutive patients with muscle-invasive bladder cancer received two or more (median = 23) fractions as oART, and remaining fractions as non-ART. The non-ART fractions were delivered with standard population-based margins, while reduced patient-specific margins based on intra-fractional variations extracted from 2-4 fractions were applied to the primary PTV (PTV-T) during the oART fractions. Target volume and coverage, and dose to OARs were compared between non-ART and oART plans, and the oART procedure time was recorded.
In total, 297/512 fractions were delivered as oART with full re-optimization to the anatomy of the day. The median (interquartile range, IQR) oART procedure time, measured from the end of CBCT generation to completion of plan review, and quality assurance was 13.9 (11.9;16.6) min. The median (IQR) volume reduction in PTV-T volume was 33.9 (24.2;45.0)%, comparing oART and non-ART plans, resulting in median (IQR) reductions in bowel bag V45Gy of 18.8 (12.7;27.9)% and rectum V50Gy of 70.7 (35.9;94.8)%. By re-optimizing the plan to the daily anatomy, full target coverage was achieved at all oART fractions.
oART resulted in large reductions in treatment volumes and doses to OARs, compared to non-ART, while ensuring target coverage. This indicates potential reductions in gastrointestinal toxicity.
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