title: Verification of respiratory-gated radiotherapy with new real-time tumour-tracking radiotherapy system using cine EPID images and a log file.
abstract: A combined system comprising the TrueBeam linear accelerator and a new real-time tumour-tracking radiotherapy system, SyncTraX, was installed at our institution. The objectives of this study are to develop a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine electronic portal image device (EPID) images and a log file and to verify this treatment in clinical cases. Respiratory-gated radiotherapy was performed using TrueBeam and the SyncTraX system. Cine EPID images and a log file were acquired for a phantom and three patients during the course of the treatment. Digitally reconstructed radiographs (DRRs) were created for each treatment beam using a planning CT set. The cine EPID images, log file, and DRRs were analysed using a developed software. For the phantom case, the accuracy of the proposed method was evaluated to verify the respiratory-gated radiotherapy. For the clinical cases, the intra- and inter-fractional variations of the fiducial marker used as an internal surrogate were calculated to evaluate the gating accuracy and set-up uncertainty in the superior-inferior (SI), anterior-posterior (AP), and left-right (LR) directions. The proposed method achieved high accuracy for the phantom verification. For the clinical cases, the intra- and inter-fractional variations of the fiducial marker were  ⩽3 mm and  ±3 mm in the SI, AP, and LR directions. We proposed a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine EPID images and a log file and showed that this treatment is performed with high accuracy in clinical cases.
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, Yamaguchi University, 1-1-1 Minamikogushi, Yamaguchi 755-8535, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Shiinoki
authors.forename: Hideki
authors.initials: H
authors.lastname: Hanazawa
authors.forename: Yuki
authors.initials: Y
authors.lastname: Yuasa
authors.forename: Koya
authors.initials: K
authors.lastname: Fujimoto
authors.forename: Takuya
authors.initials: T
authors.lastname: Uehara
authors.forename: Keiko
authors.initials: K
authors.lastname: Shibuya
mesh_terms: D003199:Computer Systems; D057918:Fiducial Markers; D006801:Humans; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D019047:Phantoms, Imaging; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D055425:Respiratory-Gated Imaging Techniques / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D012984:Software; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods* / Q000592:standards