title: Catch me if you can--the use of image guidance in the radiotherapy of an unusual case of esophageal cancer.
abstract: BACKGROUND
  Despite maximum therapy the prognosis of esophageal carcinoma still remains extremely poor. New treatment strategies including improved radiation therapy techniques promise better outcome by improving local control through precise dose delivery due to higher conformality.
  
  
  METHODS
  A 62-year-old patient with locally advanced carcinoma of the gastroesophageal junction underwent definitive radiochemotherapy with intensity-modulated radiation therapy (IMRT). On positioning control with the in-room CT, the distal esophagus, and hence the tumor, was found to be highly mobile exhibiting changes in position of up to 4 cm from fraction to fraction.
  
  
  RESULTS
  IMRT plans were created for various positions establishing a plan library to choose from as appropriate. CT scans were performed prior to each treatment fraction to clarify esophagus position in order to choose the adequate treatment plan.
  
  
  CONCLUSIONS
  Image guidance was crucial in this unusual case of esophageal carcinoma. Without the information from position control CTs, the tumor would have received only about half the prescribed dose due to variations in position. For this specific case, in-room CT scans are probably superior to kilo- or megavoltage CTs due to the higher soft-tissue contrast enabling detection of positioning variation of the organ and offering the possibility to use the CT for treatment planning.
authors.affiliation: Department of Radiation Oncology, University of Heidelberg Medical School, Heidelberg, Germany. alexandra.jensen@med.uni-heidelberg.de
authors.forename: Alexandra D
authors.initials: AD
authors.lastname: Jensen
authors.forename: Christian
authors.initials: C
authors.lastname: Grehn
authors.forename: Anna
authors.initials: A
authors.lastname: Nikoghosyan
authors.forename: Christian
authors.initials: C
authors.lastname: Thieke
authors.forename: Robert
authors.initials: R
authors.lastname: Krempien
authors.forename: Peter E
authors.initials: PE
authors.lastname: Huber
authors.forename: Jürgen
authors.initials: J
authors.lastname: Debus
authors.forename: Marc W
authors.initials: MW
authors.lastname: Münter
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D016477:Artifacts; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D019583:Dose Fractionation, Radiation; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D004943:Esophagogastric Junction / Q000473:pathology / Q000528:radiation effects; D006321:Heart / Q000528:radiation effects; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008168:Lung / Q000528:radiation effects; D008207:Lymphatic Metastasis / Q000473:pathology / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011832:Radiation Injuries / Q000000981:diagnostic imaging / Q000517:prevention & control; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D014057:Tomography, X-Ray Computed