Hybrid navigation system for tracking the position of body tissue

Abstract

A hybrid surgical navigation system for tracking the position of body tissue. The system includes a marker shaped to be mounted subcutaneously to the tissue the position of which is to be tracked. A tracker located above skin level is placed near the marker. A first navigation system integral with the marker and tracker generate data indicating the position of the marker relative to the tracker. A second navigation monitors the position of the tracker. The tracker also includes a transmitter for transmitting data generated by the first navigation system. Based on the data generated by the first navigation system representative of the position of the marker relative to the tracker and the data from the second navigation system representative of the position of the tracker, the position of the marker and tissue to which it is attached is determined.

1 . A surgical navigation system comprising: 
 a subcutaneous marker including a geometric feature shaped to attach said marker to a section of tissue;    a tracker at least partially disposed above skin surface adjacent said marker, said tracker being moveable relative to said marker;    a first navigation assembly located in said marker and said tracker for generating signals indicating the position of said marker relative to said tracker;    a second navigation assembly contained in said tracker and in a localizer spaced from said tracker for generating signals indicating the position of said tracker to said localizer; and    a processor connected to said first navigation assembly for receiving data representative of the position of said marker relative to said tracker and to said second navigation assembly for receiving data representative of the position of said tracker to said localizer and configured to, based on the received data, generate data indicating the position of said marker relative to said localizer.    
     
     
         2 . The system of  claim 1 , wherein said first navigation assembly includes: 
 a transmitter in one of said marker or said tracker for transmitting energy wirelessly; and    a transducer in the other one of said tracker or said marker for measuring the strength of the transmitted energy.    
     
     
         3 . The system of  claim 2 , wherein the energy transmitted from said marker or said tracker to the other of said tracker or said marker is either EM or RF energy.  
     
     
         4 . The system of  claim 2 , wherein the energy transmitted from the one of said marker or said tracker is transmitted at 5 Watts or less.  
     
     
         5 . The system of  claim 1 , wherein said second navigation system transmits and receives one from the following types of energy: EM energy; RF energy; light energy; sonic; and ultrasonic energy.  
     
     
         6 . A surgical tracker, said tracker comprising: 
 a transmitter for transmitting energy to a subcutaneous marker;    a receiver for receiving from the mark signals representing measurements of the transmitted energy received by the marker and    components of a remote navigation system that includes a localizer that allows the remote navigation system to determine the position of said tracker relative to the localizer; and    a transmitter connected to said receiver for wirelessly broadcasting to a remote receiver data representative of the signal measurements made by the marker.    
     
     
         7 . A method for performing surgical navigation including the steps of: 
 attaching a tracker to body tissue or a surgical device;    providing a localizer, wherein at least one of the tracker or the localizer is moveable relative to the other of the localizer or the tracker;    transmitting energy at a select frequency from the tracker to the localizer or from the localizer to the tracker;    measuring the transmitted energy received by the localizer or the tracker;    based on the measurements of energy received by the localizer or the tracker, determining the position or orientation of the tracker;    determining if a device external to the surgical navigation system is emitting energy that can potentially adversely affect said determination of the position or orientation of the tracker; and    if a device external to the surgical navigation system is emitting energy that can potentially adversely affect said determination of the position or orientation of said tracker, in said step of transmitting energy, changing the frequency at which the energy is transmitted.    
     
     
         8 . The method of performing surgical navigation of  claim 7 , wherein said step of determining if a device external to the surgical navigation system is emitting energy that can potentially adversely affect said determination of the position or orientation of the tracker is performed by monitoring the accuracy of said determination of the position or orientation of the tracker.  
     
     
         9 . The method of performing surgical navigation of  claim 7 , wherein said step of determining if a device external to the surgical navigation system is emitting energy that can potentially adversely affect said determination of the position or orientation of the tracker is performed by monitoring whether or not the external device is actuated.  
     
     
         10 . The method of performing surgical navigation of  claim 7 , wherein, in said step of transmitting energy, energy from one of the following types of energy is transmitted: electromagnetic; RF; sonic; ultrasonic; and photonic.  
     
     
         11 . The method of performing surgical navigation of  claim 7 , wherein: 
 in said step of attaching a tracker, the tracker is fitted subcutaneously to tissue of a patient; and    in said step of providing a localizer, the localizer is disposed over the patient in the vicinity of the tracker.    
     
     
         12 . The method of performing surgical navigation of  claim 11 , wherein: 
 said navigation system used to track the position and orientation of said tracker is a first navigation system;    the position or orientation of the localizer is determined; and    based on the determination of the position or orientation of the tracker relative to the localizer and the determination position or orientation of the localizer, the position or orientation of the tracker relative to a reference point is determined.