title: Intra thoracic anatomical changes in lung cancer patients during the course of radiotherapy.
abstract: OBJECTIVE
  Conebeam-CT (CBCT) guidance is often used for setup verification of lung cancer patients treated with radiotherapy. The purpose of this study was to quantify intra-thoracic anatomical changes (ITACs) during the radiotherapy treatment and to hand over a decision support system to guide the radiation therapy technologist and radiation oncologist in prioritizing these changes.
  
  
  METHODS
  1793 CBCT-scans of 177 lung cancer patients treated in 2010 in our institute with radical radiotherapy were evaluated. Our decision support system: "the Traffic Light Protocol", was retrospectively applied to these CBCT-scans. The protocol has four levels: red (immediate action before treatment), orange (action before next fraction), yellow (no action required) and green (no change).
  
  
  RESULTS
  In 128 patients (72%), 210 ITACs were observed with a maximum level of red, orange and yellow in 12%, 36% and 24% respectively. Types of observed ITACs were, tumor regression (35%), tumor baseline shift (27%), changes in atelectasis (19%), tumor progression (10%), pleural effusion (6%) and infiltrative changes (3%).
  
  
  CONCLUSIONS
  ITACs have been observed in 72% of all lung cancer patients during the course of radical radiotherapy. The clinical relevance of the proposed ITAC classification in lung radiotherapy needs to be validated in a prospective analysis.
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Margriet
authors.initials: M
authors.lastname: Kwint
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Sanne
authors.initials: S
authors.lastname: Conijn
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Eva
authors.initials: E
authors.lastname: Schaake
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: Knegjens
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Maddalena
authors.initials: M
authors.lastname: Rossi
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Remeijer
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Jan-Jakob
authors.initials: JJ
authors.lastname: Sonke
authors.affiliation: Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands. Electronic address: j.belderbos@nki.nl.
authors.forename: Jose
authors.initials: J
authors.lastname: Belderbos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D054893:Cone-Beam Computed Tomography / Q000379:methods; D019583:Dose Fractionation, Radiation; D005260:Female; D056973:Four-Dimensional Computed Tomography / Q000379:methods; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology* / Q000528:radiation effects*; D008175:Lung Neoplasms / Q000150:complications / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D010996:Pleural Effusion / Q000000981:diagnostic imaging / Q000209:etiology; D011446:Prospective Studies; D001261:Pulmonary Atelectasis / Q000000981:diagnostic imaging / Q000209:etiology; D016634:Radiosurgery / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061106:Radiotherapy Setup Errors / Q000517:prevention & control; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods; D012189:Retrospective Studies
keywords: Adaptive delivery; Cone beam CT; Image guided radiotherapy; Inter-fractional variations; Lung cancer