In:
Radiation Oncology, Springer Science and Business Media LLC, Vol. 15, No. 1 ( 2020-12)
Abstract:
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-D 95% exhibited no significant changes when considering all plans, but GTV-D 2% increased by 0.40% ± 1.5% on average ( p 〈 0.001). There was a very small yet significant decrease in GTV-coverage for the abdomen plans. The ring D mean 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.
Type of Medium:
Online Resource
ISSN:
1748-717X
DOI:
10.1186/s13014-020-01641-0
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2020
detail.hit.zdb_id:
2224965-5
Bookmarklink