title: Monitoring of respiratory movement of the diaphragm for gated radiotherapy.
abstract: OBJECTIVE
  In order to obtain a respiratory signal for gated radiotherapy, diaphragm movement was monitored.
  
  
  METHODS
  To obtain the diaphragm signal, an image brightness stabilizer for fluoroscopy of an X-ray simulator was used. The image brightness stabilizer output electric current in response to image brightness, which changed with diaphragm movement. The electric current was recorded as the diaphragm signal and compared with the abdominal wall signal, which was obtained by monitoring the height of the abdominal wall using a laser displacement sensor.
  
  
  RESULTS
  A regular diaphragm signal was obtained in all of nine patients. At 70% expiration of the abdominal wall signal, the diaphragm signal ranged from 35% to 70% expiration (median, 55%). At 30% inspiration of the abdominal wall signal, the diaphragm signal ranged from 10% to 30% inspiration (median, 20%).
  
  
  CONCLUSIONS
  A regular diaphragm signal could be conveniently obtained utilizing an image brightness stabilizer. The diaphragm signal tended to be delayed in comparison with the abdominal wall signal.
authors.affiliation: Department of Radiology, Osaka City University Graduate School of Medicine, Japan.
authors.forename: Takuhito
authors.initials: T
authors.lastname: Tada
authors.forename: Masako
authors.initials: M
authors.lastname: Hosono
authors.forename: Tomio
authors.initials: T
authors.lastname: Fujioka
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Fukuda
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Nakajima
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D003964:Diaphragm / Q000000981:diagnostic imaging / Q000502:physiology*; D005471:Fluoroscopy; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D012119:Respiration; D015656:Respiratory Mechanics