Tracking marker support structure and surface registration methods employing the same for performing navigated surgical procedures

Abstract

Devices and methods are provide for facilitating registration and calibration of surface imaging systems. Tracking marker support structures are described that include one or more fiducial reference markers, where the tracking marker support structures are configured to be removably and securely attached to a skeletal region of a patient. Methods are provided in which a tracking marker support structure is attached to a skeletal region in a pre-selected orientation, thereby establishing an intraoperative reference direction associated with the intraoperative position of the patient, which is employed for guiding the initial registration between intraoperatively acquired surface data and volumetric image data. In other example embodiments, the tracking marker support structure may be employed for assessing the validity of a calibration transformation between a tracking system and a surface imaging system. Example methods are also provided to detect whether or not a tracking marker support structure has moved from its initial position during a procedure.

1 . A surgical tool comprising:
 a functional distal portion;   a plurality of tracking markers fixed in position and orientation relative to said functional distal portion, said plurality of tracking markers being configured to be detectable by an optical tracking system; and   a geometrical marker fixed in position and orientation relative to said functional distal portion, said geometrical marker being configured to be detectable by a surface detection system;   said geometrical marker comprising a plurality of planar surfaces, wherein at least two of the planar surfaces are oriented at oblique angles relative to one another, thereby facilitating detection of said geometrical marker by the surface detection system over a range of relative orientations between said surgical tool and the surface detection system.   
     
     
         2 . The surgical tool according to  claim 1  wherein said geometrical marker is a first geometrical marker, said surgical tool further comprising a second geometrical marker. 
     
     
         3 . The surgical tool according to  claim 2  wherein said first geometrical marker and said second geometrical marker have different shapes. 
     
     
         4 . The surgical tool according to  claim 2  wherein said first geometrical marker extends from a first planar base surface and said second geometrical marker extends from a second planar base surface, wherein said first planar base surface is angled relative to said second planar base surface. 
     
     
         5 . The surgical tool according to  claim 1  wherein said geometrical marker resides closer to said functional distal portion than said plurality of tracking markers. 
     
     
         6 . The surgical tool according to  claim 1  wherein said geometrical marker has a truncated pyramidal shape. 
     
     
         7 . The surgical tool according to  claim 1  wherein said functional distal portion comprises a clamp. 
     
     
         8 . A system comprising:
 the surgical tool according to  claim 1 ;   the surface detection system;   the tracking system; and   processing and control circuitry operatively coupled to said surface detection system and said tracking system, said processing circuitry comprising at least one processor and associated memory, said memory comprising instructions executable by said at least one processor for performing operations comprising:
 employing the tracking system to determine a first position and orientation of the surgical tool in a frame of reference of said tracking system; 
 employing the surface detection system to acquire surface data, and processing the surface data and reference surface data characterizing said geometrical marker to determine a second position and orientation of the surgical tool in a frame of reference of said surface detection system; and 
 employing the first position and orientation and the second position and orientation to determine a calibration transformation between the frame of reference of said tracking system and the frame of reference of said surface detection system. 
   
     
     
         9 . The system according to  claim 8  wherein said processing and control circuitry is further configured to compare the calibration transformation to a previously determined calibration transformation to determine whether or not the previously determined calibration transformation is valid. 
     
     
         10 . The system according to  claim 9  said processing and control circuitry is further configured to employ the first position and orientation and the previously determined calibration transformation to segment the surface data within a subregion corresponding to an estimated location of the geometrical marker, thereby obtaining segmented surface data, and wherein the segmented surface data and the reference surface data are processed to determine the second position and orientation. 
     
     
         11 . The system according to  claim 8  wherein said geometrical marker is a first geometrical marker, said surgical tool further comprising a second geometrical marker. 
     
     
         12 . The system according to  claim 11  wherein said first geometrical marker and said second geometrical marker have different shapes. 
     
     
         13 . The system according to  claim 11  wherein said first geometrical marker extends from a first planar base surface and said second geometrical marker extends from a second planar base surface, wherein said first planar base surface is angled relative to said second planar base surface. 
     
     
         14 . The system according to  claim 8  wherein said geometrical marker resides closer to said functional distal portion than said plurality of tracking markers. 
     
     
         15 . The system according to  claim 8  wherein said geometrical marker has a truncated pyramidal shape. 
     
     
         16 . The system according to  claim 9  wherein said surgical tool comprises a clamp. 
     
     
         17 . A method of determining a calibration transformation between a frame of reference of a tracking system and a frame of reference of a surface detection system, the method comprising:
 providing a surgical tool according to  claim 1 ;   employing the tracking system to determine a first position and orientation of the surgical tool in a frame of reference of said tracking system;   employing the surface detection system to acquire surface data, and processing the surface data and reference surface data characterizing said geometrical marker to determine a second position and orientation of the surgical tool in a frame of reference of said surface detection system; and   employing the first position and orientation and the second position and orientation to determine the calibration transformation.   
     
     
         18 . The method according to  claim 17  further comprising comparing the calibration transformation to a previously determined calibration transformation to determine whether or not the previously determined calibration transformation is valid. 
     
     
         19 . The method according to  claim 17  wherein the first position and orientation and the previously determined calibration transformation are employed to segment the surface data within a subregion corresponding to an estimated location of the geometrical marker, thereby obtaining segmented surface data, and wherein the segmented surface data and the reference surface data are processed to determine the second position and orientation. 
     
     
         20 . The method according to  claim 17  wherein said geometrical marker resides closer to said functional distal portion than said plurality of tracking markers.