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Title: Quality assurance of non-coplanar, volumetric-modulated arc therapy employing a C-arm linear accelerator, featuring continuous patient couch rotation
Authors: Hirashima, Hideaki  kyouindb  KAKEN_id  orcid (unconfirmed)
Nakamura, Mitsuhiro  kyouindb  KAKEN_id
Miyabe, Yuki  kyouindb  KAKEN_id
Mukumoto, Nobutaka  kyouindb  KAKEN_id
Ono, Tomohiro  kyouindb  KAKEN_id
Iramina, Hiraku  kyouindb  KAKEN_id  orcid (unconfirmed)
Mizowaki, Takashi  kyouindb  KAKEN_id  orcid (unconfirmed)
Author's alias: 平島, 英明
中村, 光宏
宮部, 結城
椋本, 宜学
小野, 智博
溝脇, 尚志
Keywords: Non-coplanar VMAT
Continuous couch rotation
Developer mode
Quality assurance
Issue Date: 11-Apr-2019
Publisher: BioMed Central Ltd.
Journal title: Radiation Oncology
Volume: 14
Thesis number: 62
Abstract: Purpose: To perform quality assurance of non-coplanar, volumetric-modulated arc therapy featuring continuous couch rotation (CCR-VMAT) using a C-arm linear accelerator. Methods: We planned and delivered CCR-VMAT using the TrueBeam Developer Mode. Treatment plans were created for both a C-shaped phantom and five prostate cancer patients using seven CCR trajectories that lacked collisions; we used RayStation software (ver. 4.7) to this end. Subsequently, verification plans were generated. The mean absolute error (MAE) between the center of an MV-imaged steel ball and the radiation field was calculated using the Winston–Lutz test. The MAEs between planned and actual irradiation values were also calculated from trajectory logs. In addition, correlation coefficients (r values) among the MAEs of gantry angle, couch angle, and multi-leaf collimator (MLC) position, and mechanical parameters including gantry speed, couch speed, MLC speed, and beam output, were estimated. The dosimetric accuracies of planned and measured values were also assessed using ArcCHECK. Results: The MAEs ±2 standard deviations as revealed by the Winston–Lutz test for all trajectories were 0.3 ± 0.3 mm in two dimensions. The MAEs of the gantry, couch, and MLC positions calculated from all trajectory logs were within 0.04°, 0.08°, and 0.02 mm, respectively. Deviations in the couch angle (r = 0.98, p < 0.05) and MLC position (r = 0.86, p < 0.05) increased significantly with speed. The MAE of the beam output error was less than 0.01 MU. The mean gamma passing rate ± 2 SD (range) of the 3%/3 mm, 3%/1 mm, and 5%/1 mm was 98.1 ± 1.9% (95.7–99.6%), 87.2 ± 2.8% (80.2–96.7%), and 96.3 ± 2.8% (93.9–99.6%), respectively. Conclusions: CCR-VMAT delivered via the TrueBeam Developer Mode was associated with high-level geometric and mechanical accuracy, thus affording to high dosimetric accuracy. The CCR-VMAT performance was stable regardless of the trajectory chosen.
Rights: © The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.
DOI(Published Version): 10.1186/s13014-019-1264-6
PubMed ID: 30971273
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