1. Stereotactic MR-guided adaptive radiation therapy for peripheral lung tumors
- Author
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Suresh Senan, Femke O.B. Spoelstra, C.J.A. Haasbeek, Marjan A. Admiraal, Miguel A. Palacios, Frank J. Lagerwaard, Tobias Finazzi, A. Bruynzeel, Berend J. Slotman, CCA - Cancer Treatment and quality of life, and Radiation Oncology
- Subjects
Lung Neoplasms ,Planning target volume ,Radiosurgery ,SABR volatility model ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Humans ,Medicine ,Radiology, Nuclear Medicine and imaging ,Lung cancer ,Mr linac ,Lung ,business.industry ,Radiotherapy Planning, Computer-Assisted ,Radiotherapy Dosage ,Hematology ,medicine.disease ,Peripheral ,medicine.anatomical_structure ,Oncology ,030220 oncology & carcinogenesis ,business ,Nuclear medicine ,Mri guided ,Adaptive radiation therapy ,Radiotherapy, Image-Guided - Abstract
BACKGROUND AND PURPOSE: We studied the benefits of using stereotactic MR-guided adaptive radiation therapy (SMART) for delivery of SABR in peripherally located lung tumors.METHODS AND MATERIALS: Twenty-three patients (25 peripheral lung tumors) underwent SMART in 3-8 fractions on an MR Linac or Cobalt-60 system. Before each fraction, a breath-hold MR scan was acquired, followed by on-table plan adaptation based on the anatomy-of-the-day. Breath-hold gated delivery was performed under continuous MR-guidance using an in-room monitor. Benefits of on-table adaptation were studied by comparing 112 «predicted» plans, which are the baseline plans recalculated on the anatomy-of-the-day, with the on-table reoptimized plans.RESULTS: The full SMART procedure took a median of 48 and 62 minutes on the MR Linac and Cobalt-60 system, respectively. Median SMART-PTVs were 9.5 cm3 (range, 3.1-55.6). In 14 patients who had undergone a free-breathing 4DCT, SMART-PTVs measured 53.7% (range, 31.9-75.0) of PTVs that would have been generated using a motion-encompassing internal target volume approach. On-table adaptation improved prescription dose coverage of the PTV from a median of 92.1% in predicted plans, to 95.0% in reoptimized ones, thereby increasing the proportion of fractions delivering ≥100 Gy (BED10Gy) to 95% of PTV, from 90.2% to 100.0%.CONCLUSION: Delivery of gated breath-hold SABR using MR-guidance resulted in significantly smaller target volumes than would have been the case with an ITV-based approach. Although on-table adaptation ensured delivery of ablative doses in all fractions, the dosimetric benefits were modest, suggesting that daily online plan adaptation may not benefit most patients with peripheral lung tumors.
- Published
- 2020