title: Investigation of active tracking for robotic arm assisted magnetic resonance guided focused ultrasound ablation.
abstract: BACKGROUND
  Focused ultrasound surgery (FUS) is a technique that does not need invasive access to the patient while allowing precise targeted therapy. Magnetic resonance (MR) guided FUS provides capabilities for monitoring treatments. Because the targeted tumours are distributed at different positions, focus repositioning becomes necessary.
  
  
  METHODS
  An MR compatible robot was used to increase the operational range of FUS application. Active tracking was developed to detect the robotic arm with regard to the MR coordinate system. The purpose of this study was to construct active tracking to allow a wide spatial range of repositioning the FUS transducer that is fast and accurate. The technique was characterised and validated by a series of positioning tests to prove its efficiency for guiding the robot.
  
  
  RESULTS
  In the calibration range, tracking achieved an RMS accuracy of 0.63 mm. Results of phantom ablation showed a focal scanning precision Δx = 0.4 ± 0.37 mm, Δy = 0.4 ± 0.28 mm and Δz = 0.7 ± 0.66 mm.
  
  
  CONCLUSIONS
  The active tracking localisation can be considered a feasible approach for the MR guided FUS system positioned by a robot. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Institute for Medical Science and Technology, University of Dundee, Dundee, UK.
authors.forename: Xu
authors.initials: X
authors.lastname: Xiao
authors.affiliation: School of Engineering, Physics and Mathematics, University of Dundee, Dundee, UK.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Institute for Medical Science and Technology, University of Dundee, Dundee, UK.
authors.forename: Martin A
authors.initials: MA
authors.lastname: Rube
authors.affiliation: Institute for Medical Science and Technology, University of Dundee, Dundee, UK.
authors.forename: Andreas
authors.initials: A
authors.lastname: Melzer
mesh_terms: D002138:Calibration; D004867:Equipment Design; D057086:High-Intensity Focused Ultrasound Ablation / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008279:Magnetic Resonance Imaging; D019047:Phantoms, Imaging; D065287:Robotic Surgical Procedures / Q000295:instrumentation / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014159:Transducers; D059708:Ultrasonic Surgical Procedures / Q000295:instrumentation / Q000379:methods*
keywords: MR compatible robotic arm; MRI; MRgFUS; active tracking; focused ultrasound