title: Consequences of additional use of PET information for target volume delineation and radiotherapy dose distribution for esophageal cancer.
abstract: OBJECTIVE
  To determine the consequences of target volume (TV) modifications, based on the additional use of PET information, on radiation planning, assuming PET/CT-imaging represents the true extent of the tumour.
  
  
  METHODS
  For 21 patients with esophageal cancer, two separate TV's were retrospectively defined based on CT (CT-TV) and co-registered PET/CT images (PET/CT-TV). Two 3D-CRT plans (prescribed dose 50.4 Gy) were constructed to cover the corresponding TV's. Subsequently, these plans were compared for target coverage, normal tissue dose-volume histograms and the corresponding normal tissue complication probability (NTCP) values.
  
  
  RESULTS
  The addition of PET led to the modification of CT-TV with at least 10% in 12 of 21 patients (57%) (reduction in 9, enlargement in 3). PET/CT-TV was inadequately covered by the CT-based treatment plan in 8 patients (36%). Treatment plan modifications resulted in significant changes (p<0.05) in dose distributions to heart and lungs. Corresponding changes in NTCP values ranged from -3% to +2% for radiation pneumonitis and from -0.2% to +1.2% for cardiac mortality.
  
  
  CONCLUSIONS
  This study demonstrated that TV's based on CT might exclude PET-avid disease. Consequences are under dosing and thereby possibly ineffective treatment. Moreover, the addition of PET in radiation planning might result in clinical important changes in NTCP.
authors.affiliation: Department of Radiation Oncology, University Medical Centre Groningen/University of Groningen, Groningen, The Netherlands. c.t.muijs@rt.umcg.nl
authors.forename: Christina T
authors.initials: CT
authors.lastname: Muijs
authors.forename: Liesbeth M
authors.initials: LM
authors.lastname: Schreurs
authors.forename: Dianne M
authors.initials: DM
authors.lastname: Busz
authors.forename: Jannet C
authors.initials: JC
authors.lastname: Beukema
authors.forename: Arnout J
authors.initials: AJ
authors.lastname: van der Borden
authors.forename: Jan
authors.initials: J
authors.lastname: Pruim
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Van der Jagt
authors.forename: John Th
authors.initials: JT
authors.lastname: Plukker
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Langendijk
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18