title: An integrated system for planning, navigation and robotic assistance for skull base surgery.
abstract: BACKGROUND
  We developed an image-guided robot system to provide mechanical assistance for skull base drilling, which is performed to gain access for some neurosurgical interventions, such as tumour resection. The motivation for introducing this robot was to improve safety by preventing the surgeon from accidentally damaging critical neurovascular structures during the drilling procedure.
  
  
  METHODS
  We integrated a Stealthstation navigation system, a NeuroMate robotic arm with a six-degree-of-freedom force sensor, and the 3D Slicer visualization software to allow the robotic arm to be used in a navigated, cooperatively-controlled fashion by the surgeon. We employed virtual fixtures to constrain the motion of the robot-held cutting tool, so that it remained in the safe zone that was defined on a preoperative CT scan.
  
  
  RESULTS
  We performed experiments on both foam skull and cadaver heads. The results for foam blocks cut using different registrations yielded an average placement error of 0.6 mm and an average dimensional error of 0.6 mm. We drilled the posterior porus acusticus in three cadaver heads and concluded that the robot-assisted procedure is clinically feasible and provides some ergonomic benefits, such as stabilizing the drill. We obtained postoperative CT scans of the cadaver heads to assess the accuracy and found that some bone outside the virtual fixture boundary was cut. The typical overcut was 1-2 mm, with a maximum overcut of about 3 mm.
  
  
  CONCLUSIONS
  The image-guided cooperatively-controlled robot system can improve the safety and ergonomics of skull base drilling by stabilizing the drill and enforcing virtual fixtures to protect critical neurovascular structures. The next step is to improve the accuracy so that the overcut can be reduced to a more clinically acceptable value of about 1 mm.
authors.affiliation: Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA.
authors.forename: Tian
authors.initials: T
authors.lastname: Xia
authors.forename: Clint
authors.initials: C
authors.lastname: Baird
authors.forename: George
authors.initials: G
authors.lastname: Jallo
authors.forename: Kathryn
authors.initials: K
authors.lastname: Hayes
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Nakajima
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Hata
authors.forename: Peter
authors.initials: P
authors.lastname: Kazanzides
mesh_terms: D003399:Craniotomy / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D038361:Neuronavigation / Q000295:instrumentation* / Q000379:methods*; D019047:Phantoms, Imaging; D012371:Robotics / Q000295:instrumentation* / Q000379:methods*; D019291:Skull Base / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D013523:Surgical Equipment