Magnetic field distortion detection and correction in a magnetic localization system

A method for detecting magnetic distortion in a magnetic field for localization of a catheter within a patient, the method including:

• receiving a first set of one or more signals from a metal distortion detection fixture indicative of the magnetic field sensed by each of a plurality of sensor coils within the metal distortion detection fixture at a first time, wherein a position of the metal distortion detection fixture is located within the magnetic field,
• determining a first magnitude value of first combined signals indicative of a magnetic field at the first time,
• receiving a second set of one or more signals from the metal distortion detection fixture indicative of the magnetic field sensed by each of the plurality of sensor coils at a second time,
• determining a second magnitude value of second combined signals indicative of another magnetic field at the second time,
• determining a magnetic shift in the magnetic field between the first and second magnitude values,
• comparing the magnetic shift to a threshold shift amount indicative of a magnetic distortion in the magnetic field,
• determining whether the magnetic shift is indicative of a ferrous object within the magnetic field when the magnetic shift is greater than the threshold shift amount, and
• detecting a variance between a perceived location of the catheter within the patient and an actual location in an output from the metal distortion detection fixture in response to the magnetic shift being greater than the threshold shift amount.