title: Commissioning and quality assurance of Dynamic WaveArc irradiation.
abstract: A novel three-dimensional unicursal irradiation technique "Dynamic WaveArc" (DWA), which employs simultaneous and continuous gantry and O-ring rotation during dose delivery, has been implemented in Vero4DRT. The purposes of this study were to develop a commissioning and quality assurance procedure for DWA irradiation, and to assess the accuracy of the mechanical motion and dosimetric control of Vero4DRT. To determine the mechanical accuracy and the dose accuracy with DWA irradiation, 21 verification test patterns with various gantry and ring rotational directions and speeds were generated. These patterns were irradiated while recording the irradiation log data. The differences in gantry position, ring position, and accumulated MU (EG, ER, and EMU, respectively) between the planned and actual values in the log at each time point were evaluated. Furthermore, the doses delivered were measured using an ionization chamber and spherical phantom. The constancy of radiation output during DWA irradiation was examined by comparison with static beam irradiation. The mean absolute error (MAE) of EG and ER were within 0.1° and the maximum error was within 0.2°. The MAE of EMU was within 0.7 MU, and maximum error was 2.7 MU. Errors of accumulated MU were observed only around control points, changing gantry, and ring velocity. The gantry rotational range, in which EMU was greater than or equal to 2.0 MU, was not greater than 3.2%. It was confirmed that the extent of the large differences in accumulated MU was negligibly small during the entire irradiation range. The variation of relative output value for DWA irradiation was within 0.2%, and this was equivalent to conventional arc irradiation with a rotating gantry. In conclusion, a verification procedure for DWA irradiation was designed and implemented. The results demonstrated that Vero4DRT has adequate mechanical accuracy and beam output constancy during gantry and ring rotation.
authors.affiliation: Graduate School of Medicine, Kyoto University. syksato@kuhp.kyoto-u.ac.jp.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Sato
authors.forename: Yuki
authors.initials: Y
authors.lastname: Miyabe
authors.forename: Kunio
authors.initials: K
authors.lastname: Takahashi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamada
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Nakamura
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Ishihara
authors.forename: Kenji
authors.initials: K
authors.lastname: Yokota
authors.forename: Shuji
authors.initials: S
authors.lastname: Kaneko
authors.forename: Takashi
authors.initials: T
authors.lastname: Mizowaki
authors.forename: Hajime
authors.initials: H
authors.lastname: Monzen
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hiraoka
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D006801:Humans; D019047:Phantoms, Imaging; D011785:Quality Assurance, Health Care; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000295:instrumentation*; D061089:Radiotherapy, Image-Guided / Q000295:instrumentation*