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ID 58221
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Tanaka, Yoshihiro Department of Radiation Therapy,Japanese Red Cross Society Kyoto Daiichi Hospital
Oita, Masataka Department of Healthcare Sciences,Graduate School of Interdisciplinary Scienceand Engineering in Health Systems,Okayama University Kaken ID researchmap
Inomata, Shinichiro Department of Radiation Therapy,Japanese Red Cross Society Kyoto Daiichi Hospital
Fuse, Toshiaki Department of Radiation Therapy,Japanese Red Cross Society Kyoto Daiichi Hospital
Akino, Yuichi Oncology Center, Osaka University Hospital
Shimomura, Kohei Kyoto College of Medical Science
Abstract
The aim of this study is to evaluate the patient positioning uncertainty in noncoplanar stereotactic radiosurgery or stereotactic radiotherapy (SRS/SRT) for intracranial lesions with the frameless 6D ExacTrac system. In all, 28 patients treated with SRS/SRT of 70 treatment plans at our institution were evaluated in this study. Two X-ray images with the frameless 6D ExacTrac system were first acquired to correct (XC) and verify (XV) the patient position at a couch angle of 0o. Subsequently, the XC and XV images were also acquired at each planned couch angle for using noncoplanar beams to detect position errors caused by rotating a couch. The translational XC and XV shift values at each couch angle were calculated for each plan. The percentages of the translational XC shift values within 1.0 mm for each planned couch angle for using noncoplanar beams were 77.86%, 72.26%, and 98.47% for the lateral, longitudinal, and vertical directions, respectively. Those within 2.0 mm were 98.22%, 97.96%, and 99.75% for the lateral, longitudinal, and vertical directions, respectively. The maximum absolute values of the translational XC shifts among all planned couch angles for using noncoplanar beams were 2.69, 2.45, and 2.17 mm for the lateral, longitudinal, and vertical directions, respectively. The overall absolute values of the translational XV shifts were less than 1.0 mm for all directions except for one case in the longitudinal direction. The patient position errors were detected after couch rotation for using noncoplanar beams, and they exceeded a planning target volume (PTV) margin of 1.0-2.0 mm used commonly in SRS/SRT treatment. These errors need to be corrected at each planned couch angle, or the PTV margin should be enlarged.
Keywords
IGRT
noncoplanar radiotherapy
patient positioning uncertainty
SRS
SRT
Published Date
2020-01-20
Publication Title
Journal of Applied Clinical Medical Physics
Volume
volume21
Issue
issue2
Publisher
Wiley
Start Page
89
End Page
97
ISSN
1526-9914
NCID
AA12034060
Content Type
Journal Article
language
English
OAI-PMH Set
岡山大学
Copyright Holders
© 2020 The Authors.
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isVersionOf https://doi.org/10.1002/acm2.12820
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https://creativecommons.org/licenses/by/4.0/