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Muscle-Invasive Bladder Cancer: Novel Approach to Online Adaptive Radiotherapy

By: Amanda E. Ruffino, BA
Posted: Tuesday, January 16, 2024

Jorrit Visser, PhD, of Cancer Center Amsterdam, and colleagues have examined the feasibility of online adaptive radiotherapy for bladder cancer, incorporating simultaneous integrated boost and fiducial markers. The study used cone beam CT and artificial intelligence (AI)-assisted automatic delineation to evaluate the online treatment plan. The results, reported in the journal Radiation Oncology, suggested that this strategy, combined with fiducial markers, is viable for bladder cancer radiotherapy with a simultaneous integrated boost, meeting clinical requirements and offering potential enhancement of treatment precision.

“Improved automatic delineation to lower the need for manual corrections and faster reoptimization would result in shorter session time,” proposed the investigators.

A total of 15 patients underwent daily online adaptive radiotherapy with the study’s prescribed use of cone beam CT and AI assistance for automatic delineation. The treatment involved delivering 40 Gy to the bladder and pelvic lymph nodes, supplemented by a 15-Gy simultaneous integrated boost to the tumor. The researchers assessed dose distribution, target coverage, manual adjustments of gross tumor volume delineation, workflow duration, and the impact of fiducial markers.

All 300 adaptive plans consistently met clinical requirements, ensuring coverage for both the boost (55 Gy) and elective volume (40 Gy). Adaptive plans showed significantly reduced tissue receiving 55 Gy compared with scheduled plans, which the study authors believe indicates improved precision. Manual corrections of gross tumor volume occurred in 67% of sessions, with 96% resulting in a median 1% improvement in target coverage. The median on-couch time was 22 minutes, with one-third attributed to plan reoptimization. Fiducial markers were visible with the study’s use of cone beam CT, aiding consistent tumor localization.

Disclosure: For the study authors’ full disclosures, visit

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