title: Optimizing radiation treatment plans for lung cancer using lung perfusion information.
abstract: OBJECTIVE
  To study the impact of incorporation of lung perfusion information in the optimization of radical radiotherapy (RT) treatment plans for patients with medically inoperable non-small cell lung cancer (NSCLC).
  
  
  METHODS
  The treatment plans for a virtual phantom and for five NSCLC patients with typical defects of pre-RT lung perfusion were optimized to minimize geometrically determined parameters as the mean lung dose (MLD), the lung volume receiving more than 20 Gy (V20), and the functional equivalent of the MLD, using perfusion-weighted dose-volume histograms. For the patients the (perfusion-weighted) optimized plans were compared to the clinically applied treatment plans.
  
  
  RESULTS
  The feasibility of perfusion-weighted optimization was demonstrated in the phantom. Using perfusion information resulted in an increase of the weights of those beams that were directed through the hypo-perfused lung regions both for the phantom and for the studied patients. The automatically optimized dose distributions were improved with respect to lung toxicity compared with the clinical treatment plans. For patients with one hypo-perfused hemi-thorax, the estimated gain in post-RT lung perfusion was 6% of the prescribed dose compared to the geometrically optimized plan. For patients with smaller perfusion defects, perfusion-weighted optimization resulted in the same plan as the geometrically optimized plan.
  
  
  CONCLUSIONS
  Perfusion-weighted optimization resulted in clinically well applicable treatment plans, which cause less radiation damage to functioning lung for patients with large perfusion defects.
authors.affiliation: Department of Radiotherapy, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
authors.forename: Yvette
authors.initials: Y
authors.lastname: Seppenwoolde
authors.forename: Martijn
authors.initials: M
authors.lastname: Engelsman
authors.forename: Katrien
authors.initials: K
authors.lastname: De Jaeger
authors.forename: Sara H
authors.initials: SH
authors.lastname: Muller
authors.forename: Paul
authors.initials: P
authors.lastname: Baas
authors.forename: Daniel L
authors.initials: DL
authors.lastname: McShan
authors.forename: Benedick A
authors.initials: BA
authors.lastname: Fraass
authors.forename: Marc L
authors.initials: ML
authors.lastname: Kessler
authors.forename: José S A
authors.initials: JS
authors.lastname: Belderbos
authors.forename: Liesbeth J
authors.initials: LJ
authors.lastname: Boersma
authors.forename: Joos V
authors.initials: JV
authors.lastname: Lebesque
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy*; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000528:radiation effects; D008175:Lung Neoplasms / Q000532:radiotherapy*; D019047:Phantoms, Imaging; D011652:Pulmonary Circulation; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D015899:Tomography, Emission-Computed, Single-Photon