title: Comparing digital tomosynthesis to cone-beam CT for position verification in patients undergoing partial breast irradiation.
abstract: OBJECTIVE
  To evaluate digital tomosynthesis (DTS) technology for daily positioning of patients receiving accelerated partial breast irradiation (APBI) and to compare the positioning accuracy of DTS to three-dimensional cone-beam computed tomography (CBCT).
  
  
  METHODS
  Ten patients who underwent APBI were scanned daily with on-board CBCT. A subset of the CBCT projections was used to reconstruct a stack of DTS image slices. To optimize soft-tissue visibility, the DTS images were reconstructed in oblique directions so that the tumor bed, breast tissue, ribs, and lungs were well separated. Coronal and sagittal DTS images were also reconstructed. Translational shifts of DTS images were obtained on different days from the same patients and were compared with the translational shifts of corresponding CBCT images. Seventy-seven CBCT scans and 291 DTS scans were obtained from nine evaluable patients.
  
  
  RESULTS
  Tumor beds were best visible in the oblique DTS scans. One-dimensional positioning differences between DTS and CBCT images were 0.8-1.7 mm for the six patients with clips present and 1.2-2.0 mm for the three patients without clips. Because of the limited DTS scan angle, the DTS registration accuracy along the off-plane direction is lower than the accuracy along the in-plane directions.
  
  
  CONCLUSIONS
  For patients receiving APBI, DTS localization offers comparable accuracy to CBCT localization for daily patient positioning while reducing mechanical constraints and imaging dose.
authors.affiliation: Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA. junan.zhang@duke.edu
authors.forename: Junan
authors.initials: J
authors.lastname: Zhang
authors.forename: Q Jackie
authors.initials: QJ
authors.lastname: Wu
authors.forename: Devon J
authors.initials: DJ
authors.lastname: Godfrey
authors.forename: Toyosi
authors.initials: T
authors.lastname: Fatunase
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Marks
authors.forename: Fang-Fang
authors.initials: FF
authors.lastname: Yin
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D004867:Equipment Design; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D015588:Observer Variation; D011832:Radiation Injuries / Q000517:prevention & control; D011856:Radiographic Image Enhancement / Q000379:methods*; D011879:Radiotherapy Dosage