Treatment plan quality during online adaptive re-planning
- PDF / 743,168 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 77 Downloads / 147 Views
RESEARCH
Open Access
Treatment plan quality during online adaptive re-planning Janita E. van Timmeren* , Madalyne Chamberlain, Jérôme Krayenbuehl, Lotte Wilke, Stefanie Ehrbar, Marta Bogowicz, Callum Hartley, Mariangela Zamburlini, Nicolaus Andratschke, Helena Garcia Schüler, Matea Pavic, Panagiotis Balermpas, Chaehee Ryu, Matthias Guckenberger and Stephanie Tanadini-Lang
Abstract Background: Online adaptive radiotherapy is intended to prevent plan degradation caused by inter-fractional tumor volume and shape changes, but time limitations make online re-planning challenging. The aim of this study was to compare the quality of online-adapted plans to their respective reference treatment plans. Methods: Fifty-two patients treated on a ViewRay MRIdian Linac were included in this retrospective study. In total 238 online-adapted plans were analyzed, which were optimized with either changing of the segment weights (n = 85) or full re-optimization (n = 153). Five different treatment sites were evaluated: prostate, abdomen, liver, lung and pelvis. Dosimetric parameters of gross tumor volume (GTV), planning target volume (PTV), 2 cm ring around the PTV and organs at risk (OARs) were considered. The Wilcoxon signed-rank test was used to assess differences between online-adapted and reference treatment plans, p < 0.05 was considered significant. Results: The average duration of the online adaptation, consisting of contour editing, plan optimization and quality assurance (QA), was 24 ± 6 min. The GTV was slightly larger (average ± SD: 1.9% ± 9.0%) in the adapted plans than in the reference plans (p < 0.001). GTV-D95% exhibited no significant changes when considering all plans, but GTVD2% increased by 0.40% ± 1.5% on average (p < 0.001). There was a very small yet significant decrease in GTVcoverage for the abdomen plans. The ring Dmean increased on average by 1.0% ± 3.6% considering all plans (p < 0.001). There was a significant reduction of the dose to the rectum of 4.7% ± 16% on average (p < 0.001) for prostate plans. Conclusions: Dosimetric quality of online-adapted plans was comparable to reference treatment plans and OAR dose was either comparable or decreased, depending on treatment site. However, dose spillage was slightly increased. Keywords: Radiotherapy, MR-linac, Online-adaptive radiation therapy, MR-guided, MRgRT, Online, Adaptive, Planning, SBRT
* Correspondence: [email protected] Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Rämistrasse 100, 8091 Zürich, Switzerland © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless in
Data Loading...
