title: Adaptive radiotherapy of lung cancer patients with pleural effusion or atelectasis.
abstract: OBJECTIVE
  Changes in lung density due to atelectasis, pleural effusion and pneumonia/pneumonitis are observed in lung cancer patients. These changes may be an indication for adaptive radiotherapy in order to maintain target coverage and avoid increased risk of normal tissue complications.
  
  
  METHODS
  CBCT scans of 163 patients were reviewed to score lung changes and find the incidence, the impact of geometric and dosimetric changes and the timing of appearance and disappearance of changes.
  
  
  RESULTS
  23% of the patients had changes in the lung related to pleural effusion, atelectasis or pneumonia/pneumonitis. In 9% of all patients, the appearance or disappearance of a change introduced a shift of the tumor or lymph nodes relative to the spine >5mm. Only major density changes affected the dose distribution, and 9% of all patients needed adaptive treatment planning due to density changes. In total, 12% of all patients did benefit from an adaptive treatment plan and in 85% of these patients, an atelectasis did change.
  
  
  CONCLUSIONS
  An adaptive strategy was indicated for 12% of the patients due to atelectasis, pleural effusion or pneumonia/pneumonitis. The predominant cause for adaptation was atelectasis. No systematic pattern in the appearance and disappearance of the changes were observed and hence weekly evaluation is preferable.
authors.affiliation: Department of Medical Physics, Aarhus University Hospital, Denmark. Electronic address: dittmoel@rm.dk.
authors.forename: Ditte Sloth
authors.initials: DS
authors.lastname: Møller
authors.affiliation: Department of Oncology, Aarhus University Hospital, Denmark.
authors.forename: Azza Ahmed
authors.initials: AA
authors.lastname: Khalil
authors.affiliation: Department of Oncology, Aarhus University Hospital, Denmark.
authors.forename: Marianne Marquard
authors.initials: MM
authors.lastname: Knap
authors.affiliation: Department of Medical Physics, Aarhus University Hospital, Denmark.
authors.forename: Lone
authors.initials: L
authors.lastname: Hoffmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000150:complications / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000209:etiology*; D001261:Pulmonary Atelectasis / Q000209:etiology*; D011879:Radiotherapy Dosage
keywords: Adaptive RT; Atelectasis; IGRT; NSCLC; SCLC