title: Automated intraoperative calibration for prostate cancer brachytherapy.
abstract: OBJECTIVE
  Prostate cancer brachytherapy relies on an accurate spatial registration between the implant needles and the TRUS image, called "calibration". The authors propose a new device and a fast, automatic method to calibrate the brachytherapy system in the operating room, with instant error feedback.
  
  
  METHODS
  A device was CAD-designed and precision-engineered, which mechanically couples a calibration phantom with an exact replica of the standard brachytherapy template. From real-time TRUS images acquired from the calibration device and processed by the calibration system, the coordinate transformation between the brachytherapy template and the TRUS images was computed automatically. The system instantly generated a report of the target reconstruction accuracy based on the current calibration outcome.
  
  
  RESULTS
  Four types of validation tests were conducted. First, 50 independent, real-time calibration trials yielded an average of 0.57 ± 0.13 mm line reconstruction error (LRE) relative to ground truth. Second, the averaged LRE was 0.37 ± 0.25 mm relative to ground truth in tests with six different commercial TRUS scanners operating at similar imaging settings. Furthermore, testing with five different commercial stepper systems yielded an average of 0.29 ± 0.16 mm LRE relative to ground truth. Finally, the system achieved an average of 0.56 ± 0.27 mm target registration error (TRE) relative to ground truth in needle insertion tests through the template in a water tank.
  
  
  CONCLUSIONS
  The proposed automatic, intraoperative calibration system for prostate cancer brachytherapy has achieved high accuracy, precision, and robustness.
authors: Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors: Thomas
authors: T
authors: Kuiran Chen
authors: Tamas
authors: T
authors: Heffter
authors: Andras
authors: A
authors: Lasso
authors: Csaba
authors: C
authors: Pinter
authors: Purang
authors: P
authors: Abolmaesumi
authors: E Clif
authors: EC
authors: Burdette
authors: Gabor
authors: G
authors: Fichtinger
mesh_terms: D001331:Automation; D001918:Brachytherapy / Q000379:methods*; D002138:Calibration; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000601:surgery*; D013997:Time Factors; D014463:Ultrasonography