title: Magnetic resonance imaging-compatible, three-degrees-of-freedom joystick for surgical robot.
abstract: BACKGROUND
  This paper presents a magnetic resonance (MR) compatible joystick for controlling a surgical robot arm. The surgical robot can be used to assist the surgeon in high precision neurosurgery tasks. Conventional joysticks cannot be used in magnetic resonance imaging (MRI) environments, because they generally contain ferromagnetic materials such as iron, which create distortions in MR images. Moreover, dangerous situations may arise, when an object containing ferromagnetic materials passes through the strong magnetic field of an imaging device. Currents generated by device electronics produce magnetic fields that distort MR images.
  
  
  METHODS
  Operation of the joystick described here is based on measuring light intensity. Optical fibres are used for target illumination and for transmitting the reflected light. Their use enables the joystick electronics to be kept at a safe distance from the imaging machine.
  
  
  RESULTS
  Experimental results prove that the joystick can be constructed on the presented operating principle using the designed mechanical structure. When the joystick was placed 15 cm away from the phantom object, it didn't cause any distortion to the MR image.
  
  
  CONCLUSIONS
  The developed joystick can be used in an MRI environment. However, further development need to be done in order to avoid losses caused by bending optical fibres.
authors.affiliation: Department of Electrical and Information Engineering, University of Oulu, Finland. juha.harja@ee.oulu.fi
authors.forename: Juha
authors.initials: J
authors.lastname: Harja
authors.forename: Jussi
authors.initials: J
authors.lastname: Tikkanen
authors.forename: Hannu
authors.initials: H
authors.lastname: Sorvoja
authors.forename: Risto
authors.initials: R
authors.lastname: Myllylä
mesh_terms: D016287:Computer Peripherals; D004867:Equipment Design; D019544:Equipment Failure Analysis; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008328:Man-Machine Systems; D012371:Robotics / Q000295:instrumentation* / Q000379:methods; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D014159:Transducers; D014584:User-Computer Interface