title: Target volume definition for upper abdominal irradiation using CT scans obtained during inhale and exhale phases.
abstract: OBJECTIVE
  To evaluate the clinical utility of a treatment-planning technique involving the use of CT images obtained during both the static exhalation phase and static inhalation phase (two-phase planning).
  
  
  METHODS
  Ten patients with pancreatic or liver tumors underwent CT scanning under static exhale and inhale conditions, after a period of mild ventilation. By setting image positions differently, we were able to treat the two-phase images as one dataset. Each gross tumor volume (GTV) was contoured separately and the mixed GTV was used for the two-phase treatment planning. Treatment plans were constructed to compare the two-phase plans with the plans constructed using static exhalation images. The shift of the center of the GTV and kidneys and the minimum dose of GTV were then calculated.
  
  
  RESULTS
  The shift of the GTV ranged from 2.6 to 27. 3 mm and that of the kidneys from 2.2 to 24 mm. In some patients whose treatment was planned using exhalation planning, the minimum dose of GTV at inhalation was less than 90% of the isocenter dose.
  
  
  CONCLUSIONS
  Two-phase planning is a simple technique that can visualize tumor and organ movement simultaneously using CT. It further defines adequate field margins around the tumor and prevents unexpected radiation exposure to critical organs. Routine use of this technique for upper abdominal irradiation is recommended.
authors.affiliation: Department of Radiology, Chiba University Hospital, Chiba, Japan. arugat@hotmail.com
authors.forename: T
authors.initials: T
authors.lastname: Aruga
authors.forename: J
authors.initials: J
authors.lastname: Itami
authors.forename: M
authors.initials: M
authors.lastname: Aruga
authors.forename: K
authors.initials: K
authors.lastname: Nakajima
authors.forename: K
authors.initials: K
authors.lastname: Shibata
authors.forename: T
authors.initials: T
authors.lastname: Nojo
authors.forename: S
authors.initials: S
authors.lastname: Yasuda
authors.forename: T
authors.initials: T
authors.lastname: Uno
authors.forename: R
authors.initials: R
authors.lastname: Hara
authors.forename: K
authors.initials: K
authors.lastname: Isobe
authors.forename: N
authors.initials: N
authors.lastname: Machida
authors.forename: H
authors.initials: H
authors.lastname: Ito
mesh_terms: D000008:Abdominal Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000556:secondary; D009068:Movement; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012119:Respiration; D014057:Tomography, X-Ray Computed