Patent ID: 7805269

Claim:
A method for detecting and correcting an existence of one or more distortions in an electromagnetic field created using a magnetic tracking device for image guided surgery, wherein the one or more distortions originate from a volume of space where a medical procedure is to be performed using the magnetic tracking device and decrease an accuracy of the magnetic tracking device, the method comprising: placing, prior to performing the medical procedure, a rigid object into the volume of space, wherein the rigid object comprises one or more position indicating elements at one or more known locations of the rigid object, and wherein the one or more position indicating elements are associated with baseline position and orientation information that indicates known position and orientation of the one or more known locations prior to first use of the rigid object; obtaining sampled position and orientation information of the one or more position indicating elements in the volume of space; comparing the sampled position and orientation information to the baseline position and orientation information of the one or more position indicating elements; and determining the existence of the one or more distortions in the electromagnetic field that originated from the volume of space and that are imposed upon the one or more known locations based on the comparison, whereby the decrease in the accuracy of the magnetic tracking device resulting from the one or more distortions is at least partially correctable based on the determination when the medical procedure using the magnetic tracking device is performed.