Method of determining the position of an instrument relative to a body of a patient

Abstract

A system for determining a position of a probe relative to an object such as a head of a body of a patient. The head includes a surface such as a forehead having a contour. Cross sectional images of the head are scanned and stored as a function of the forehead contour. If the forehead contour does not appear in the scan images, then the position of the forehead contour relative to the scan images is determined with an optical scanner and a ring. During surgery, the optical scanner also determines the position of the forehead relative to the ring. An array for receiving radiation emitted from the probe and from the ring generates signals indicating the position of the tip of the probe relative to the ring. A stereotactic imaging system generates and displays an image of the head corresponding to the measured position of the tip of the probe. The system may also display scan images from different scanning technologies which scan images correspond to the same position in the head.

1 . A method for determining a position relative to a body of a patient in a coordinate system, the method comprising: 
 radiating first signals from a base fixed in relation to the body of the patient, the signals representing the position of the base and the body in the coordinate system;    radiating second signals from an instrument positioned relative to the body, the signals representing the position of the instrument in the coordinate system;    receiving the first and second signals; and    processing the first and second signals to determine the position of the instrument relative to the base and the body in the coordinate system.    
     
     
         2 . The method of  claim 1 , further including retrieving scanned images of the body; determining the position of the body in the images of the body; and translating the position of the instrument relative to the body in the coordinate system to the position of the instrument relative to the body in the images of the body.  
     
     
         3 . The method of  claim 2 , further including displaying the position of the instrument relative to the body in the images of the body.  
     
     
         4 . A method for indicating a location relative to the body of a patient, the method comprising the steps of: 
 fixing reference points in relation to the body;    providing body signals from the reference points, the signals representing the position of the reference points and the body;    positioning an instrument relative to the body, the instrument being located remote from the body;    providing instrument signals from the instrument, the signals representing the position of the instrument;    receiving the body and instrument signals; and    determining the position of the instrument relative to the reference points and the body based on the body and instrument signals.    
     
     
         5 . The method of  claim 4 , further including obtaining a scan image of the body, determining the position of the body in the scan image of the body; and translating the position of the instrument relative to the body to the position of the instrument relative to the body in the scan images of the body.  
     
     
         6 . The method of  claim 4 , further including displaying the position of the instrument relative to the body.  
     
     
         7 . A method for determining a position relative to a body of a patient in a coordinate system, the method comprising: 
 radiating first signals from the body of the patient, the signals representing the position of the body in the coordinate system;    radiating second signals from an instrument positioned relative to the body, the signals representing the position of the instrument in the coordinate system;    receiving the first and second signals; and    processing the first and second signals to determine the position of the instrument relative to the body in the coordinate system.    
     
     
         8 . The method of  claim 7 , further including retrieving scanned images of the body; determining the position of the body in the images of the body; and translating the position of the instrument relative to the body in the coordinate system to the position of the instrument relative to the body in the images of the body.  
     
     
         9 . The method of  claim 8 , further including displaying the position of the instrument relative to the body in the images of the body.