Tracking marker support structure and surface registration methods employing the same for performing navigated surgical procedures
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 method of detecting a change in a position and orientation of a tracking marker support structure relative to a patient, the method comprising:
a) employing a surface imaging system to acquire first intraoperative surface data associated with a surgical region of interest, the first intraoperative surface data being associated with a first known position and orientation of the tracking marker support structure, wherein the tracking marker support structure is secured to the patient;
b) subsequently employing the surface imaging system to acquire second intraoperative surface data associated with the surgical region, the second intraoperative surface data being associated with a second known position and orientation of the tracking marker support structure;
c) registering the second intraoperative surface data with the first intraoperative surface data to obtain an intraoperative transformation; and
d) processing the intraoperative transformation, the first known position and orientation of the tracking marker support structure, and the second known position and orientation of the tracking marker support structure to determine the change in the position and orientation of the tracking marker support structure relative to the patient.
2. The method according to claim 1 further comprising alerting a user when the change in the position and orientation of the tracking marker support structure relative to the patient exceeds a pre-selected threshold.
3. The method according to claim 1 further comprising interrupting intraoperative guidance when the change in the position and orientation of the tracking marker support structure relative to the patient exceeds a pre-selected threshold.
4. The method according to claim 1 further comprising performing steps b) through d) one or more times during a surgical procedure to monitor changes in the position and orientation of the tracking marker support structure relative to the patient.
5. The method according to claim 4 wherein steps b) through d) are repeated at a prescribed frequency.
6. The method according to claim 4 wherein steps b) through d) are repeated when performing a subsequent step of a surgical plan.
7. The method according to claim 1 wherein step b) is initiated in response to input received from an operator.
8. The method according to claim 1 wherein the tracking marker support structure comprises a plurality of fiducial markers, and wherein signals associated with the plurality of fiducial markers are employed to determine the first known position and orientation of the tracking marker support structure and the second known position and orientation of the tracking marker support structure.
9. The method according to claim 1 wherein the surface imaging system is employed to determine the known second position and orientation of the tracking marker support structure by processing additional surface data associated with the tracking marker support structure.