title: Validation of active breathing control in patients with non-small-cell lung cancer to be treated with CHARTWEL.
abstract: OBJECTIVE
  Active breathing control (ABC) was validated using patients with non-small-cell lung cancer (NSCLC) to be treated with continuous hyperfractionated accelerated radiotherapy weekend-less (CHARTWEL). Effects of breath hold (BH) on accuracy and normal tissue doses were evaluated.
  
  
  METHODS
  Eleven patients were studied. Immediately after a free breathing (FB) planning scan, two ABC scans (ABC 1 and 2) were performed to assess intrafraction variation. A third ABC scan (ABC 3) was performed some weeks later to assess interfraction variation. Assisted BH was set at 75% of vital capacity and reproducibility assessed using computed tomography (CT) lung volumes. Planning target volumes (PTVs), doses to lung and spinal cord for FB and ABC 1 scans were compared.
  
  
  RESULTS
  Results were available for 10 patients. Disease and elective nodal regions were easier to define on ABC scans making PTVs smaller. ABC lung volumes showed no significant variation over several weeks, percentage volume of whole lung receiving > or =20 Gy (V(20)) was reduced in all (median 6.4%, p = 0.005), and spinal cord dose in 80% (median 1.03 Gy, p = 0.02), of the plans.
  
  
  CONCLUSIONS
  ABC allowed reproducible BH, and enabled better delineation of tumor and normal structures, as well as reduction in PTV, V(20), and spinal cord dose.
authors.affiliation: Department of Clinical OncologyMount Vernon Cancer Centre, Northwood, Middlesex, UK. EMW@tinyworld.co.uk
authors.forename: Elena M
authors.initials: EM
authors.lastname: Wilson
authors.forename: F Joy
authors.initials: FJ
authors.lastname: Williams
authors.forename: B Ethan
authors.initials: BE
authors.lastname: Lyn
authors.forename: John W
authors.initials: JW
authors.lastname: Wong
authors.forename: Edwin G A
authors.initials: EG
authors.lastname: Aird
mesh_terms: D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D004867:Equipment Design; D005260:Female; D006801:Humans; D001239:Inhalation; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012119:Respiration; D014057:Tomography, X-Ray Computed; D014797:Vital Capacity