Patent ID: 9733336
Date: 2017-08-15
CPC Classifications: A61B,G01S

Claim:
1. A method for local error compensation caused by metal distortions in using an Electromagnetic Tracking System (EMTS) comprising the acts of: generating an electromagnetic field from at least one electromagnetic field generator; monitoring a positional reading of a medical device in an anatomy using a current induced by the electromagnetic field in at least one electromagnetic sensor coil of the medical device; monitoring position readings from at least three electromagnetic sensors of an error correction tool that surrounds a region of interest and is configured to monitor the metal distortions wherein said error correction tool is situated within proximity of said medical device to obtain a monitored geometric shape, wherein the at least three electromagnetic sensors are arranged in a known and fixed configuration forming a reference geometric shape, and wherein said error correcting tool includes at least one optical tracking sensor attached to said error correcting tool in a fixed known position relative to at least one electromagnetic sensor of the at least three electromagnetic sensors; comparing the monitored geometric shape with the reference geometric shape to obtain a comparison result; deriving a correction function from said comparison result, wherein the correction function translates the monitored geometric shape to yield a corrected monitored geometric shape that conforms to the reference geometric shape of the at least three electromagnetic sensors; applying said corrective function to said positional reading of the medical device to compensate for said metal distortions and obtain a corrected positional reading indicating a corrected position of the medical device, wherein the at least one optical tracking sensor is configured to provide optical data in an optical tracking space and the position readings from at least three electromagnetic sensors are in an electromagnetic tracking space; registering the optical tracking space and the electromagnetic tracking space to an imaging system configured to display images of the medical device in the anatomy; and obtaining absolute positions of the at least three electromagnetic sensors based on the registering act.