title: Four-dimensional measurement of the displacement of internal fiducial and skin markers during 320-multislice computed tomography scanning of breast cancer.
abstract: OBJECTIVE
  To study the three-dimensional movement of internal tumor bed fiducial and breast skin markers, using 320-multislice computed tomography (CT); and to analyze intrafractional errors for breast cancer patients undergoing breast irradiation.
  
  
  METHODS
  This study examined 280 markers on the skin of the breast (200 markers) and on the primary tumor bed (80 markers) of 20 patients treated by external-beam photon radiotherapy. Motion assessment was analyzed in 41 respiratory phases during 20 s of cine CT in the radiotherapy position. To assess intrafractional errors resulting from respiratory motion, four-dimensional CT scans were acquired for 20 patients.
  
  
  RESULTS
  Motion in the anterior-posterior (A/P) and superior-inferior (S/I) directions showed a strong correlation (|r| > 0.7) with the respiratory curve for most markers (79% and 70%, respectively). The average marker displacements between maximum and minimum value during 20 s for the 200 breast skin metal markers were 1.1 ± 0.3 mm, 2.1 ± 0.6 mm, and 1.6 ± 0.4 mm in the left-right, A/P, and S/I directions, respectively. For the 80 tumor bed clips, displacements were 0.9 ± 0.2 mm in left-right, 1.7 ± 0.5 mm in A/P, and 1.1 ± 0.3 mm in S/I. There was no significant difference in the motion between breast quadrant regions or between the primary site and the other regions.
  
  
  CONCLUSIONS
  Motion in primary breast tumors was evaluated with 320-multislice CT. Very little change was detected during individual radiation treatment fractions.
authors.affiliation: Department of Radiology, University of Tokyo Hospital, Tokyo, Japan. yamachan07291973@yahoo.co.jp
authors.forename: Hideomi
authors.initials: H
authors.lastname: Yamashita
authors.forename: Kae
authors.initials: K
authors.lastname: Okuma
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Tada
authors.forename: Kenshiro
authors.initials: K
authors.lastname: Shiraishi
authors.forename: Wataru
authors.initials: W
authors.lastname: Takahashi
authors.forename: Shino
authors.initials: S
authors.lastname: Shibata-Mobayashi
authors.forename: Akira
authors.initials: A
authors.lastname: Sakumi
authors.forename: Naoya
authors.initials: N
authors.lastname: Saotome
authors.forename: Akihiro
authors.initials: A
authors.lastname: Haga
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Onoe
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: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D019583:Dose Fractionation, Radiation; D005260:Female; D057918:Fiducial Markers; D056973:Four-Dimensional Computed Tomography / Q000379:methods*; D006801:Humans; D007564:Japan; D008168:Lung / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D008176:Lung Volume Measurements; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009068:Movement; D061330:Multidetector Computed Tomography / Q000379:methods*; D012119:Respiration; D047368:Tumor Burden