title: A Novel Evaluation Method for Displacement between Carbon Beam Axis and Positioning X-ray Axis Using an Imaging Plate.
abstract: We developed an evaluation method for easily calculating displacement directly between the carbon beam axis and positioning X-ray axis.
  
  
  
  A verification image was acquired by irradiating an imaging plate with a carbon beam and X-ray. The X-ray passed through a lead plate inserted in the range compensator holder. The displacement was calculated on the verification image from the center of a wire irradiated with carbon using a multi leaf collimator (MLC) and a wire irradiated with X-ray also using MLC. The accuracy of the method was evaluated by moving the carbon beam axis, the X-ray axis, and the setup angle. The weekly changes of vertical and lateral beams in all rooms were also evaluated.
  
  
  
  The displacements of the carbon beam axis and the setup angle did not influence the calculation results, whereas the displacement of the X-ray axis did (R=0.999). The displacements including weekly changes were all less than 1.00 mm.
  
  
  
  An evaluation method for calculating the displacement directly and simply between the carbon beam axis and positioning X-ray axis was developed and verified. The weekly changes of displacement between axes were evaluated to be acceptable at our facility.
authors.affiliation: Department of Radiology, Gunma University Hospital.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kurosawa
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Kubota
authors.forename: Eri
authors.initials: E
authors.lastname: Takeshita
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Okada
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Ohashi
authors.forename: Hikaru
authors.initials: H
authors.lastname: Souda
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ishii
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sutou
authors.forename: Tatsuaki
authors.initials: T
authors.lastname: Kanai
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ohno
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
mesh_terms: D002244:Carbon; D013679:Technology, Radiologic / Q000295:instrumentation* / Q000379:methods*; D014965:X-Rays
chemical_list: D002244:Carbon