Time of flight technique used for measuring position and orientation of laparoscopic surgery tools

An ultrasound wireless positioning system is developed to localize the laparoscopic instruments inside the patient's body. The cross correlation method applied for measuring time of flight of ultrasound bursts yields 1 mm resolution in determining the instrument position. The 90/spl deg/ or respectively 180/spl deg/ phase-shift is introduced after the first half of the ultrasound burst.