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Original Article

Korean Journal of Medical Physics 2016; 27(3): 169-174

Published online September 30, 2016

Copyright © Korean Society of Medical Physics.

Treatment Plan Delivery Accuracy of the ViewRay System in Two-Headed Mode

Jong Min Park*†‡§, So-Yeon Park*†‡, Hong-Gyun Wu*†‡║, Jung-in Kim*†‡

*Department of Radiation Oncology, Biomedical Research Institute, Seoul National University Hospital, Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, §Center for Convergence Research on Robotics, Advanced Institutes of Convergence Technology, Suwon, ║Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea

Received: September 22, 2016; Revised: September 23, 2016; Accepted: September 24, 2016

Abstract

The aim of this study is to investigate the delivery accuracy of intensity-modulated radiation therapy (IMRT) plans in the two-headed mode of the ViewRayTM system in comparison with that of the normal operation treatment plan of the machine. For this study, a total of eight IMRT plans and corresponding verification plans were generated (four head and neck, two liver, and two prostate IMRT plans). The delivered dose distributions were measured using ArcCHECKTM with the insertion of an ionization chamber. We measured the delivered dose distributions in three-headed mode (normal operation of the machine), two-headed mode with head 1 disabled, two-headed mode with head 2 disabled, and two-headed mode with head 3 disabled. Therefore, a total of four measurements were performed for each IMRT plan. The global gamma passing rates (3%/3 mm) in three-headed mode, head 1 disabled, head 2 disabled, and head 3 disabled were 99.9±0.1%, 99.8±0.3%, 99.6±0.7%, and 99.7±0.4%, respectively. The difference in the gamma passing rates of the three- and two-headed modes was insignificant. With 2%/2 mm, the rates were 96.6±3.6%, 97.2±3.5%, 95.7±6.2%, and 95.5±4.3%, respectively. Between three-headed mode and head 3 disabled, a statistically significant difference was observed with a p-value of 0.02; however, the difference was minimal (1.1%). The chamber readings showed differences of approximately 1% between three- and two-headed modes, which were minimal. Therefore, the treatment plan delivery in the two-headed mode of the ViewRayTM system seems accurate and robust.

KeywordsMRI-guided radiation therapy system, Two-headed mode, Co-60, Intensity modulated radiation therapy

Korean Society of Medical Physics

Vol.35 No.1
March 2024

pISSN 2508-4445
eISSN 2508-4453
Formerly ISSN 1226-5829

Frequency: Quarterly

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