title: Prostate implant reconstruction from C-arm images with motion-compensated tomosynthesis.
abstract: OBJECTIVE
  Accurate localization of prostate implants from several C-arm images is necessary for ultrasound-fluoroscopy fusion and intraoperative dosimetry. The authors propose a computational motion compensation method for tomosynthesis-based reconstruction that enables 3D localization of prostate implants from C-arm images despite C-arm oscillation and sagging.
  
  
  METHODS
  Five C-arm images are captured by rotating the C-arm around its primary axis, while measuring its rotation angle using a protractor or the C-arm joint encoder. The C-arm images are processed to obtain binary seed-only images from which a volume of interest is reconstructed. The motion compensation algorithm, iteratively, compensates for 2D translational motion of the C-arm by maximizing the number of voxels that project on a seed projection in all of the images. This obviates the need for C-arm full pose tracking traditionally implemented using radio-opaque fiducials or external trackers. The proposed reconstruction method is tested in simulations, in a phantom study and on ten patient data sets.
  
  
  RESULTS
  In a phantom implanted with 136 dummy seeds, the seed detection rate was 100% with a localization error of 0.86 ± 0.44 mm (Mean ± STD) compared to CT. For patient data sets, a detection rate of 99.5% was achieved in approximately 1 min per patient. The reconstruction results for patient data sets were compared against an available matching-based reconstruction method and showed relative localization difference of 0.5 ± 0.4 mm.
  
  
  CONCLUSIONS
  The motion compensation method can successfully compensate for large C-arm motion without using radio-opaque fiducial or external trackers. Considering the efficacy of the algorithm, its successful reconstruction rate and low computational burden, the algorithm is feasible for clinical use.
authors: School of Computing, Queen's University, Kingston, Ontario, Canada.
authors: Ehsan
authors: E
authors: Dehghan
authors: Mehdi
authors: M
authors: Moradi
authors: Xu
authors: X
authors: Wen
authors: Danny
authors: D
authors: French
authors: Julio
authors: J
authors: Lobo
authors: W James
authors: WJ
authors: Morris
authors: Septimiu E
authors: SE
authors: Salcudean
authors: Gabor
authors: G
authors: Fichtinger
mesh_terms: D000465:Algorithms; D001918:Brachytherapy / Q000379:methods*; D002138:Calibration; D004867:Equipment Design; D005471:Fluoroscopy / Q000379:methods; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods; D009038:Motion; D009991:Oscillometry / Q000379:methods; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011874:Radiometry / Q000379:methods*; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000379:methods