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ID 116183
Author
Honda, Hirofumi Ehime University|Tokushima University
Oita, Masataka Okayama University
Kanzaki, Hiromitsu National Hospital Organization Shikoku Cancer Center
Hamamoto, Yasushi National Hospital Organization Shikoku Cancer Center
Ishii, Yoshiaki Ehime University
Yamamoto, Ryuji Ehime University
Mochizuki, Teruhito Ehime University
Kido, Teruhito Ehime University
Keywords
prostate
transmission detector
volumetric‐modulated arc therapy
Content Type
Journal Article
Description
Volumetric‐modulated arc therapy (VMAT) requires highly accurate control of multileaf collimator (MLC) movement, rotation speed of linear accelerator gantry, and monitor units during irradiation. Pretreatment validation and monitoring of these factors during irradiation are necessary for appropriate VMAT treatment. Recently, a gantry mounted transmission detector “Delta4 Discover® (D4D)” was developed to detect errors in delivering doses and dose distribution immediately after treatment. In this study, the performance of D4D was evaluated. Simulation plans, in which the MLC position was displaced by 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mm from the clinically used original plans, were created for ten patients who received VMAT treatment for prostate cancer. Dose deviation (DD), distance‐to‐agreement (DTA), and gamma index analysis (GA) for each plan were evaluated by D4D. These results were compared to the results (DD, DTA and GA) measured by Delta4 Phantom + (D4P). We compared the deviations between the planned and measured values of the MLC stop positions A‐side and B‐side in five clinical cases of prostate VMAT during treatment and measured the GA values. For D4D, when the acceptable errors for DD, DTA, and GA were determined to be ≤3%, ≤2 mm, and ≤3%/2 mm, respectively, the minimum detectable errors in the MLC position were 2.0, 1.5, and 1.5 mm based on DD, DTA, and GA respectively. The corresponding minimum detectable MLC position errors were 2.0, 1.0, and 1.5 mm, respectively, for D4P. The deviation between the planned and measured position of MLC stopping point of prostate VMAT during treatment was stable at an average of −0.09 ± 0.05 mm, and all GA values were above 99.86%. In terms of delivering doses and dose distribution of VMAT, error detectability of D4D was comparable to that of D4P. The transmission‐type detector “D4D” is thus suitable for detecting delivery errors during irradiation.
Journal Title
Journal of Applied Clinical Medical Physics
ISSN
15269914
NCID
AA12034060
Publisher
Wiley Periodicals|American Association of Physicists in Medicine
Volume
22
Issue
7
Start Page
66
End Page
76
Published Date
2021-05-05
Rights
This is an open access article under the terms of the Creative Commons Attribution License(https://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium,provided the original work is properly cited.
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DOI (Published Version)
URL ( Publisher's Version )
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language
eng
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departments
Medical Sciences
Bioscience and Bioindustry