title: Four-dimensional measurement of intrafractional respiratory motion of pancreatic tumors using a 256 multi-slice CT scanner.
abstract: OBJECTIVE
  To quantify pancreas and pancreatic tumor movement due to respiratory motion using volumetric cine CT images.
  
  
  METHODS
  Six patients with pancreatic tumors were scanned in cine mode with a 256 multi-slice CT scanner under free breathing conditions. Gross tumor volume (GTV) and pancreas were manually contoured on the CT data set by a radiation oncologist. Intrafractional respiratory movement of the GTV and pancreas was calculated, and the results were compared between the respiratory ungated and gated phases, which is a 30% duty cycle around exhalation.
  
  
  RESULTS
  Respiratory-induced organ motion was observed mainly in the anterior abdominal side than the posterior side. Average GTV displacement (ungated/gated phases) was 0.7 mm/0.2mm in both the left and right directions, and 2.5mm/0.9 mm in the anterior, 0.1 mm/0mm in the posterior, and 8.9 mm/2.6mm in the inferior directions. Average pancreas center of mass displacement relative to that at peak exhalation was mainly in the inferior direction, at 9.6mm in the ungated phase and 2.3mm in the gated phase.
  
  
  CONCLUSIONS
  By allowing accurate determination of the margin, quantitative analysis of tumor and pancreas displacement provides useful information in treatment planning in all radiation approaches for pancreatic tumors.
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan. shinshin@nirs.go.jp
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Mori
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Hara
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yanagi
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Sharp
authors.forename: Motoki
authors.initials: M
authors.lastname: Kumagai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Asakura
authors.forename: Riwa
authors.initials: R
authors.lastname: Kishimoto
authors.forename: Shigeru
authors.initials: S
authors.lastname: Yamada
authors.forename: Susumu
authors.initials: S
authors.lastname: Kandatsu
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kamada
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D015656:Respiratory Mechanics / Q000502:physiology*; D014057:Tomography, X-Ray Computed / Q000379:methods*