title: Evaluation of deep inspiration breath-hold lung treatment plans with Monte Carlo dose calculation.
abstract: OBJECTIVE
  To evaluate dosimetry of deep inspiration breath-hold (DIBH) relative to free breathing (FB) for three-dimensional conformal radiation therapy of lung cancer with 6-MV photons and Monte Carlo (MC) dose calculations.
  
  
  METHODS
  Static three-dimensional conformal radiation therapy, 6-MV plans, based on DIBH and FB CT images for five non-small-cell lung cancer patients, were generated on a clinical treatment planning system with equivalent path length tissue inhomogeneity correction. Margins of gross to planning target volume were not reduced for DIBH plans. Cord and lung toxicity determined the maximum treatment dose for each plan. Dose distributions were recalculated for the same beams with an MC dose calculation algorithm and electron density distributions derived from the CT images.
  
  
  RESULTS
  MC calculations showed decreased target coverage relative to treatment-planning system predictions. Lateral disequilibrium caused more degradation of target coverage for DIBH than for FB (approximately 4% worse than expected for FB vs. 8% for DIBH). However, with DIBH higher treatment doses could be delivered without violating normal tissue constraints, resulting in higher total doses to gross target volume and to >99% of planning target volume.
  
  
  CONCLUSIONS
  If DIBH enables prescription dose increases exceeding 10%, MC calculations indicate that, despite lateral disequilibrium, higher doses will be delivered to medium-to-large, partly mediastinal gross target volumes, providing that 6-MV photons are used and margins are not reduced.
authors.affiliation: Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. yorkee@mskcc.org
authors.forename: Ellen D
authors.initials: ED
authors.lastname: Yorke
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.forename: Kenneth E
authors.initials: KE
authors.lastname: Rosenzweig
authors.forename: Dennis
authors.initials: D
authors.lastname: Mah
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Paoli
authors.forename: Chen-Shou
authors.initials: CS
authors.lastname: Chui
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009010:Monte Carlo Method; D017785:Photons; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000379:methods*; D012119:Respiration