2D-3D image registration method and medical operating robot system for performing the same

An image registration method, steps of which are performed by an image registration apparatus comprising a processor, the method comprising:

• acquiring a 3D image of a patient's surgical site from a 3D imaging apparatus before an operation;
• extracting digitally reconstructed radiograph (DRR) images in an anterior-posterior (AP) direction and a lateral-lateral (LL) direction from the 3D image;
• acquiring 2D images for an AP image and an LL image of the patient's surgical site from a 2D imaging apparatus during an operation;
• determining, by the image registration apparatus, a first region of interest for each of the AP image and the LL image;
• determining, by the image registration apparatus, a second region of interest corresponding to the first region of interest for each of the AP image and the LL image of the 2D images;
• determining, by the image registration apparatus, a first volume of interest where planes intersect as a region of interest on the AP image and a region of interest on the LL image are moved in directions of first normal vectors for planes of the AP image and the LL image, from a geospatial relationship between a source and a detector for the DRR images;
• determining, by the image registration apparatus, a second volume of interest where the planes intersect as the region of interest on the AP image and the region of interest on the LL image are moved in directions of second normal vectors for planes of the AP image and the LL image within a perspective projection relationship, wherein the geospatial relationship between the source and the detector for the 2D images comprises a perspective projection relationship;
• determining a first rotation angle between a reference position and a first reference position of the patient's surgical site corresponding to the first reference position of the AP image or the LL image, based on a first rotation axis passing through a first origin and parallel to a cross product vector of the first normal vectors, from a geospatial relationship between the source and the detector with respect to the DRR images;
• determining a second rotation angle between the reference position and a second reference position of the AP image or LL image corresponding to the reference position, based on a second rotation axis passing through a second origin and parallel to a cross product vector of the second normal vectors, from a geospatial relationship between the source and the detector with respect to the 2D images;
• and
• determining a transformation relationship between the 2D images and the DRR images based on the first rotation angle and the second rotation angle, from the geospatial relationship between sources and detectors of the DRR images and the 2D images,
• wherein the first reference position is positioned within the first region of interest, and the second reference position is positioned within the second region of interest, the first origin comprises a center of the first volume of interest, and the second origin comprises a center of the second volume of interest.