Online adaptive radiotherapy of urinary bladder cancer with full re-optimization to the anatomy of the day: initial experience and dosimetric benefits

Lina M. Åström*, Claus P. Behrens, Lucie Calmels, David Sjöström, Poul Geertsen, Lene Sonne Mouritsen, Eva Serup-Hansen, Henriette Lindberg, Patrik Sibolt

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

2 Downloads (Pure)

Abstract

Background and purpose: 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 nonadaptive 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.
Materials and methods: 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.
Results: 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) minutes. 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 V 45Gy 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.
Conclusions: 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.
Original languageEnglish
JournalRadiotherapy and Oncology
Volume171
Pages (from-to)37-42
ISSN0167-8140
DOIs
Publication statusPublished - 2022

Keywords

  • Online adaptive radiotherapy
  • Bladder cancer
  • Re-optimization
  • Artificial intelligence
  • Cone-beam CT
  • Image-guided radiotherapy

Fingerprint

Dive into the research topics of 'Online adaptive radiotherapy of urinary bladder cancer with full re-optimization to the anatomy of the day: initial experience and dosimetric benefits'. Together they form a unique fingerprint.

Cite this