Dose-Escalated Magnetic Resonance Image–Guided Abdominopelvic Reirradiation With Continuous Intrafraction Visualization, Soft Tissue Tracking, and Automatic Beam Gating

Michael D. Chuong, John M. Bryant, Roberto Herrera, James McCulloch, Jessika Contreras, Rupesh Kotecha, Tino Romaguera, Diane Alvarez, Matthew D. Hall, Muni Rubens, Minesh P. Mehta, Adeel Kaiser, Martin Tom, Alonso N. Gutierrez, Kathryn E. Mittauer

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: Compared with computed tomography, magnetic resonance (MR) image guidance offers significant advantages for radiation therapy (RT) that may be particularly beneficial for reirradiation (reRT). However, clinical outcomes of MR-guided reRT are not well described in the published literature. Methods and Materials: We performed a single-institution retrospective safety and efficacy analysis of reRT patients treated on the MRIdian Linac to targets within the abdomen or pelvis using continuous intrafraction MR-based motion management with automatic beam triggering. Fiducial markers were not used. Results: We evaluated 11 patients who received prior RT to a median of 50 Gy (range, 30-58.8 Gy) in 25 fractions (range, 5-28 fractions). The median interval to reRT was 26.8 months. The most frequently retreated sites were nodal metastases (36.4%) and pancreatic cancer (27.3%). The median reRT dose was 40 Gy (range, 25-54 Gy) in 6 fractions (range, 5-36 fractions); ultrahypofractionation (63.6%) was more common than hyperfractionation (36.4%). Daily on-table adaptive replanning was used for 3 patients (27.3%). With a median of 14 months’ follow-up from reRT completion (range, 6-32 months), the median and 1-year freedom from local progression were 29 months and 88.9%, respectively, and the median and 1-year overall survival were 17.5 months and 70.0%, respectively. One patient (9.1%) experienced acute grade 2 toxic effects; there were no acute or late treatment-related toxic effects of grade 3 or greater. Conclusions: Magnetic resonance–guided reRT appeared to be feasible and may facilitate safe dose escalation. Additional follow-up is needed to better assess long-term efficacy and late toxic effects. Prospective evaluation of this novel treatment strategy is warranted.

Original languageEnglish (US)
Article number100840
JournalAdvances in Radiation Oncology
Volume7
Issue number2
DOIs
StatePublished - Mar 1 2022
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging

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