Ultrasonic motor driving method for EMI-free image in MR image-guided surgical robotic system

Electromagnetic interference (EMI) between magnetic resonance (MR) imager and surgical manipulator is a severe problem, that degrades the image quality, in MR image- guided surgical robotic systems. We propose a novel motor driving method to acquire noise-free image. Noise generation accompanied by motor actuation is permitted only during the "dead time" when the MR imager stops signal acquisition to wait for relaxation of protons. For the synchronized control between MR imager and motor driving system, we adopted a radio-frequency pulse signal detected by a special antenna as a synchronous trigger. This method can be applied widely because it only senses a part of the scanning signal and requires neither hardware nor software changes to the MR imager. The evaluation results showed the feasibility of RF pulse as a synchronous trigger and the availability of sequence-based noise reduction method.