title: Patterns of intrafractional motion and uncertainties of treatment setup reference systems in accelerated partial breast irradiation for right- and left-sided breast cancer.
abstract: OBJECTIVE
  This study investigated the patterns of intrafractional motion and accuracy of treatment setup strategies in 3-dimensional conformal radiation therapy of accelerated partial breast irradiation (APBI) for right- and left-sided breast cancers.
  
  
  METHODS
  Sixteen right-sided and 17 left-sided breast cancer patients were enrolled in an institutional APBI trial in which gold fiducial markers were strategically sutured to the surgical cavity walls. Daily pre- and postradiation therapy kV imaging were performed and were matched to digitally reconstructed radiographs based on bony anatomy and fiducial markers, respectively, to determine the intrafractional motion. The positioning differences of the laser-tattoo and the bony anatomy-based setups with respect to the marker-based setup (benchmark) were determined to evaluate their accuracy.
  
  
  RESULTS
  Statistical differences were found between the right- and left-sided APBI treatments in vector directions of intrafractional motion and treatment setup errors in the reference systems, but less in their overall magnitudes. The directional difference was more pronounced in the lateral direction. It was found that the intrafractional motion and setup reference systems tended to deviate in the right direction for the right-sided breast treatments and in the left direction for the left-sided breast treatments.
  
  
  CONCLUSIONS
  It appears that the fiducial markers placed in the seroma cavity exhibit side dependent directional intrafractional motion, although additional data may be needed to further validate the conclusion. The bony anatomy-based treatment setup improves the accuracy over laser-tattoo. But it is inadequate to rely on bony anatomy to assess intrafractional target motion in both magnitude and direction.
authors.affiliation: Department of Radiation Oncology, Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, New Jersey. Electronic address: yuenj@umdnj.edu.
authors.forename: Ning J
authors.initials: NJ
authors.lastname: Yue
authors.affiliation: Department of Radiation Oncology, Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, New Jersey.
authors.forename: Sharad
authors.initials: S
authors.lastname: Goyal
authors.affiliation: Department of Radiation Oncology, Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, New Jersey.
authors.forename: Leonard H
authors.initials: LH
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, New Jersey.
authors.forename: Atif
authors.initials: A
authors.lastname: Khan
authors.affiliation: Department of Radiation Oncology, Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, New Jersey.
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Haffty
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D057918:Fiducial Markers; D006801:Humans; D056888:Patient Positioning / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061089:Radiotherapy, Image-Guided / Q000379:methods