title: Concept and simulation study of a novel localization method for robotic endoscopic capsules using multiple positron emission markers.
abstract: OBJECTIVE
  Over the last decade, wireless capsule endoscope has been the tool of choice for noninvasive inspection of the gastrointestinal tract, especially in the small intestine. However, the latest clinical products have not been equipped with a sufficiently accurate localization system which makes it difficult to determine the location of intestinal abnormalities, and to apply follow-up interventions such as biopsy or drug delivery. In this paper, the authors present a novel localization method based on tracking three positron emission markers embedded inside an endoscopic capsule.
  
  
  METHODS
  Three spherical(22)Na markers with diameters of less than 1 mm are embedded in the cover of the capsule. Gamma ray detectors are arranged around a patient body to detect coincidence gamma rays emitted from the three markers. The position of each marker can then be estimated using the collected data by the authors' tracking algorithm which consists of four consecutive steps: a method to remove corrupted data, an initialization method, a clustering method based on the Fuzzy C-means clustering algorithm, and a failure prediction method.
  
  
  RESULTS
  The tracking algorithm has been implemented inMATLAB utilizing simulation data generated from the Geant4 Application for Emission Tomography toolkit. The results show that this localization method can achieve real-time tracking with an average position error of less than 0.4 mm and an average orientation error of less than 2°.
  
  
  CONCLUSIONS
  The authors conclude that this study has proven the feasibility and potential of the proposed technique in effectively determining the position and orientation of a robotic endoscopic capsule.
authors.affiliation: School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522, Australia.
authors.forename: Trung Duc
authors.initials: TD
authors.lastname: Than
authors.affiliation: School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522, Australia.
authors.forename: Gursel
authors.initials: G
authors.lastname: Alici
authors.affiliation: Department of Nuclear Medicine, Wollongong Hospital, New South Wales 2500, Australia.
authors.forename: Steven
authors.initials: S
authors.lastname: Harvey
authors.affiliation: School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522, Australia.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhou
authors.affiliation: School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522, Australia.
authors.forename: Weihua
authors.initials: W
authors.lastname: Li
mesh_terms: D000465:Algorithms; D053705:Capsule Endoscopes; D016000:Cluster Analysis; D003198:Computer Simulation; D005240:Feasibility Studies; D005720:Gamma Rays; D006801:Humans; D008954:Models, Biological; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D011829:Radiation Dosage; D012371:Robotics; D012979:Sodium Radioisotopes; D012984:Software; D013997:Time Factors
chemical_list: D012979:Sodium Radioisotopes