Method and system for determining an optimal position of a surgical instrument relative to a patient's bone tracker

A method for determining an optimal position of a surgical instrument relative to trackers respectively attached to at least two patient's bones using a cone beam computed tomography (CBCT) imaging system and a computer, the method comprising the following steps:

• (a) receiving at least one preoperative 2D X-ray image of the at least two bones while the patient is in a posture of interest;
• (b) acquiring at least one intraoperative 3D CBCT medical image of each bone by the cone beam computed tomography (CBCT) imaging system while the patient is in an operative posture, in which a position and an orientation of each bone relative to another anatomical structure of the patient is different from the one in the posture of interest, each of the at least one intraoperative 3D CBCT medical image being registered with the coordinate system of each bone tracker;
• (c) performing one of steps c1) and c2) with the computer:
• (c1) determining a region around each bone in the at least one preoperative 2D X-ray image and registering said at least one region onto the intraoperative 3D CBCT medical image, so as to obtain a registered region around each bone in the intraoperative 3D CBCT medical image representing each bone in the posture of interest, respectively;
• (c2) determining a region around each bone in the intraoperative 3D CBCT medical image and registering said region onto the at least one preoperative 2D X-ray image, so as to obtain a registered region around each bone in the at least one 2D preoperative X-ray image representing each bone in the posture of interest, respectively;
• (c3) computing with the computer an integrated 3D medical image from the registered regions determined in step (c1) or (c2);
• (d) planning with the computer a surgical procedure on the integrated 3D medical image taking into account said posture of interest;
• (e) determining with the computer an optimal position of the surgical instrument relative to the patient's bone trackers for implementing said planned surgical procedure.

A system for determining an optimal position of a surgical instrument relative to at least one tracker attached to a respective patient's bone, comprising:

• a medical imaging system configured to acquire at least one cone beam computed tomography (CBCT) intraoperative image of the patient;
• a localization device;
• a computer configured to receive images from the medical imaging system and localization data from the localization device and to implement at least one of the following methods:
• (A) a first method comprising:
• (a) receiving at least one preoperative 2D X-ray image of the bone while the patient is in a posture of interest;
• (b) acquiring an intraoperative 3D CBCT medical image of the bone by the cone beam computed tomography (CBCT) imaging system while the patient is in an operative posture in which a position and an orientation of the bone relative to another anatomical structure of the patient is different from the position posture of interest, the intraoperative 3D CBCT image being registered with the coordinate system of the bone tracker;
• (c) registering the intraoperative 3D CBCT medical image onto the at least one preoperative 2D X-ray image, so as to obtain a registered 3D image representing the bone in the posture of interest;
• (d) planning a surgical procedure on the registered 3D medical image taking into account said posture of interest;
• (e) determining an optimal position of the surgical instrument relative to the patient's bone tracker for implementing said planned surgical procedure;
• and
• (B) a second method comprising:
• (a) receiving at least one preoperative 2D X-ray image of the at least two bones while the patient is in a posture of interest;
• (b) acquiring at least one intraoperative 3D CBCT medical image of each bone by the cone beam computed tomography (CBCT) imaging system while the patient is in an operative posture in which a position and an orientation of each bone relative to another anatomical structure of the patient is different from the posture of interest, each intraoperative 3D CBCT medical image being registered with the coordinate system of each bone tracker;
• (c) performing one of steps c1) and c2):
• (c1) determining a region around each bone in the at least one preoperative 2D X-ray image and registering said at least one region onto the intraoperative 3D CBCT medical image, so as to obtain a registered region around each bone in the intraoperative 3D CBCT medical image representing each bone in the position posture of interest, respectively;
• (c2) determining a region around each bone in the intraoperative 3D CBCT medical image and registering said region onto the at least one preoperative 2D X-ray image, so as to obtain a registered region around each bone in the at least one 2D preoperative X-ray image representing each bone in the posture of interest, respectively;
• (c3) computing an integrated 3D medical image from the registered regions determined in step (c1) or (c2);
• (d) planning a surgical procedure on the integrated 3D medical image taking into account said posture of interest;
• (e) determining an optimal position of the surgical instrument relative to the patient's bone trackers for implementing said planned surgical procedure.