Abstract

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Title:: Preliminary study on accuracy of real-time positioning with optical surface monitoring system during radiotherapy for head tumor

Author(s):: ZHANG Bailin; DAI Zhenhui; ZHU Lin; YANG Geng; ZHU Yuanhu; ZHAO Shiwu; CAI Chunya; LI Fei; WANG Xuetao; Radiotherapy Center, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510006, China

Keywords:: ; head tumor; optical surface monitoring system; cone beam CT; positioning error; stereotactic radiotherapy

Abstract:: Abstract: Objective To evaluate the deviation detection accuracy of optical surface monitoring system (OSMS) in Varian linear accelerator EDGE. Methods A head phantom was used to evaluate the positioning accuracy before treatment, monitor the position shift during treatment and assess the performance of OSMS under certain conditions (non-zero couch angle or only two cameras at work). Results OSMS achieved the positioning before treatment, and the deviation range between the positioning with CBCT and that with OSMS was (0.6±0.5) mm, with a maximum angle deviation of 0.3°. Moreover, the deviation range of position shift during treatment between OSMS and CBCT was (0.1±0.2) mm, and the deviation range of detection angle was 0.10°±0.07°. Even at different couch angles, the accuracy of OSMS was similar. However, an uncertainty of 0.5 mm was generated when one of cameras was blocked. Conclusion OSMS combined with CBCT in radiotherapy for head tumors can provide guarantee for positioning before treatment and real-time monitoring during treatment.