title: Horizon stabilized--dynamic view expansion for robotic assisted surgery (HS-DVE).
abstract: OBJECTIVE
  New surgical approaches based on natural orifice transluminal surgery (NOTES) have the potential to further decrease morbidity and hospital stay. However, a number of key challenges have been identified preventing its clinical adoption, including inadequate instrument design and spatial disorientation. Furthermore, retroflexion, missing fixed anatomical references, and limited field-of-view are key factors contributing to disorientation in NOTES.
  
  
  METHODS
  A hybrid approach of integrated orientation sensing and real-time vision processing is proposed to restore orientation cues for improved surgical navigation. The distal tip of an articulated robotic endoscope is equipped with an inertial measurement unit (IMU) enabling video images to be reoriented and stabilized with respect to the horizon. This is performed by measuring the direction of gravity in relation to the cameras. Dynamic view expansion is used to increase the field-of-view of the endoscope. The method registers past video images to the current image and creates an enlarged visualization of the anatomy through simultaneous localization and mapping (SLAM).
  
  
  RESULTS
  The clinical potential of the system is demonstrated on a NOTES appendectomy procedure performed on the NOSsE phantom. This involves an articulated robotic endoscope navigating to visualize the appendix while retroflexed. The horizon stabilization is additionally evaluated quantitatively against known ground truth.
  
  
  CONCLUSIONS
  The combination of horizon stabilization and dynamic view expansion presents a realistic approach for reintroducing orientation and navigation cues during NOTES. The platform allows real-time implementation, which is an important prerequisite for further clinical evaluation.
authors.affiliation: The Hamlyn Centre for Robotic Surgery, Imperial College London, London, UK. arw04@ic.ac.uk
authors.forename: Alexander
authors.initials: A
authors.lastname: Warren
authors.forename: Peter
authors.initials: P
authors.lastname: Mountney
authors.forename: David
authors.initials: D
authors.lastname: Noonan
authors.forename: Guang-Zhong
authors.initials: GZ
authors.lastname: Yang
mesh_terms: D000818:Animals; D001062:Appendectomy / Q000379:methods; D003198:Computer Simulation; D004195:Disease Models, Animal; D019723:Endoscopes; D004867:Equipment Design; D004869:Equipment Safety; D021621:Imaging, Three-Dimensional; D057605:Natural Orifice Endoscopic Surgery / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D012371:Robotics / Q000379:methods*; D012680:Sensitivity and Specificity; D012984:Software; D013552:Swine