title: Spatial orientation in pathway surgery.
abstract: BACKGROUND
  In the field of minimally invasive surgery, specifically in pathway surgery (i.e. minimal invasive procedures carried out transluminally or through instrument-created pathways), spatial disorientation is a common experience to endoscopists. In this article, two effects that may cause spatial disorientation in pathway surgery, 'control-display compatibility' and 'local disorientation', were studied.
  
  
  METHODS
  A custom-developed simulator Endo-PaC was developed and used for mimicking pathway surgical scenarios. In Study 1, two ways of control-display alignment, normal mapping and mirrored mapping, were tested in combination with two control devices, thumb control and wrist control, in an orienting task using Endo-PaC. In Study 2, a tethered viewpoint was added to the virtual instrument tip. It was hypothesized that the visible tip would provide a cue of orientating direction in the reference frame during the instrument navigation. In both studies, novice participants were involved, and their performance was evaluated with regard to task time, path length travelled by the virtual tip, time and number of warnings, and subjective workload and personal preference.
  
  
  RESULTS
  In Study 1, normal-thumb and normal-wrist mapping yielded significantly lower means than mirrored-thumb and mirrored-wrist control for all investigated objective and subjective performance measurements. Out of 24 participants, 20 participants preferred normal control mapping. In Study 2, participants performed the task in shorter time and with shorter path length when the tip was visible tip on the monitor using a tethered viewpoint, but with a lower number and time of warnings without a visible tip.
  
  
  CONCLUSIONS
  The results of our studies show that eliminating the visual-display misalignment would greatly improve novice participants' performance, reduce the training time and their cognitive workload. A visible tip on the monitor would provide strong direction cue and shorten the performance time, but might introduce collision errors to novices and therefore requires longer training time.
authors.affiliation: Department BioMechanical Engineering, Faculty Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands, c.fan@tudelft.nl.
authors.forename: Chunman
authors.initials: C
authors.lastname: Fan
authors.forename: Dimitra
authors.initials: D
authors.lastname: Dodou
authors.forename: Paul
authors.initials: P
authors.lastname: Breedveld
authors.forename: Jenny
authors.initials: J
authors.lastname: Dankelman
mesh_terms: D000328:Adult; D004724:Endoscopy / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000295:instrumentation / Q000379:methods; D009949:Orientation; D012984:Software; D013028:Space Perception; D014584:User-Computer Interface; D055815:Young Adult