title: Accurate calibration method for 3D freehand ultrasound probe using virtual plane.
abstract: OBJECTIVE
  In this paper a new, easy-to-manufacture and easy-to-use ultrasound (US) probe calibration phantom for 3D freehand scanning is presented and evaluated, together with a new method for achieving an accurate and user-robust calibration using virtual plane.
  
  
  METHODS
  The phantom allows the optically tracked US probe to perform two rotations and two translations while keeping the image of a tensioned wire in the image plane. This approach allows obtaining a sharp image of the wire independently from the probe pose. The virtual plane allows the calibration algorithm to converge minimizing the required number of US probe tracked poses. The US image and position data are synchronized via a CORBA interface, created within the Image Guided Surgery Toolkit (IGSTK) framework. The calibration algorithm and the calibration protocol were evaluated in a set of experiments carried out by different test-users.
  
  
  RESULTS
  The calibration method proved to be accurate and precise: 3D point reconstruction accuracy resulted 0.2 mm as mean value, while the precision was 0.4 mm as standard deviation.
  
  
  CONCLUSIONS
  The technique showed to be suitable for medical applications from morphological diagnosis to intraoperative surgical planning adaption.
authors.affiliation: Politecnico di Milano, Bioengineering Department, Neuroengineering and Medical Robotics Laboratory, Milano 20133, Italy.
authors.forename: Danilo
authors.initials: D
authors.lastname: De Lorenzo
authors.forename: Alberto
authors.initials: A
authors.lastname: Vaccarella
authors.forename: Ghassan
authors.initials: G
authors.lastname: Khreis
authors.forename: Holger
authors.initials: H
authors.lastname: Moennich
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Ferrigno
authors.forename: Elena
authors.initials: E
authors.lastname: De Momi
mesh_terms: D000465:Algorithms; D002138:Calibration; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000592:standards; D021621:Imaging, Three-Dimensional / Q000379:methods* / Q000592:standards; D007558:Italy; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation* / Q000592:standards