title: Four-dimensional measurement of the displacement of internal fiducial markers during 320-multislice computed tomography scanning of thoracic esophageal cancer.
abstract: OBJECTIVE
  To investigate the three-dimensional movement of internal fiducial markers placed near esophageal cancers using 320-multislice CT.
  
  
  METHODS
  This study examined 22 metal markers in the esophageal wall near the primary tumors of 12 patients treated with external-beam photon radiotherapy. Motion assessment was analyzed in 41 respiratory phases during 20 s of cine CT in the radiotherapy position.
  
  
  RESULTS
  Motion in the cranial-caudal (CC) direction showed a strong correlation (R(2) > 0.4) with the respiratory curve in most markers (73%). The average absolute amplitude of the marker movement was 1.5 ± 1.6 mm, 1.6 ± 1.7 mm, and 3.3 ± 3.3 mm in the left-right (LR), anterior-posterior (AP), and CC directions, respectively. The average marker displacements in the CC direction between peak exhalation and inhalation for the 22 clips were 1.1 mm (maximum, 5.5 mm), 3.0 mm (14.5 mm), and 5.1 mm (16.3 mm) for the upper, middle, and lower thoracic esophagus, respectively.
  
  
  CONCLUSIONS
  Motion in primary esophagus tumor was evaluated with 320-multislice CT. According to this study, 4.3 mm CC, 1.5 mm AP, and 2.0 mm LR in the upper, 7.4 mm CC, 3.0 mm AP, and 2.4 mm LR in the middle, and 13.8 mm CC, 6.6 mm AP, and 6.8 mm LR in the lower thoracic esophagus provided coverage of tumor motion in 95% of the cases in our study population.
authors.affiliation: Department of Radiology, University of Tokyo Hospital, Tokyo, Japan.
authors.forename: Hideomi
authors.initials: H
authors.lastname: Yamashita
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kida
authors.forename: Akira
authors.initials: A
authors.lastname: Sakumi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Haga
authors.forename: Saori
authors.initials: S
authors.lastname: Ito
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Onoe
authors.forename: Kae
authors.initials: K
authors.lastname: Okuma
authors.forename: Kenji
authors.initials: K
authors.lastname: Ino
authors.forename: Masaaki
authors.initials: M
authors.lastname: Akahane
authors.forename: Kuni
authors.initials: K
authors.lastname: Ohtomo
authors.forename: Keiichi
authors.initials: K
authors.lastname: Nakagawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging*; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D057918:Fiducial Markers; D056973:Four-Dimensional Computed Tomography / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009038:Motion; D009068:Movement; D013902:Radiography, Thoracic; D012119:Respiration