Method for registering a 3D medical image with a registration phantom

An intraoperative surgical system comprising:

• a registration phantom comprising a set of radiopaque fiducials having a known position in a coordinate system of said registration phantom, said registration phantom being adapted to be positioned onto a patient,
• an X-ray imaging system configured to acquire a set of 2D X-ray images and to reconstruct a 3D medical image from said set of 2D X-ray images, and
• a computer system configured to:
• (i) obtain at least two 2D X-ray images acquired by the X-ray imaging system wherein at least three radiopaque fiducials of the registration phantom are detectable in each 2D image;
• (ii) for each obtained 2D image, register the 2D X-ray image with the registration phantom by detecting and determining the position of the at least three radiopaque fiducials in the respective 2D image;
• (iv) compute for each 2D X-ray image, back-projection rays from the determined positions of said radiopaque fiducials in the respective 2D X-ray image based on a projection matrix of the X-ray imaging system;
• (iv) determine the position of each of said at least three radiopaque fiducials relative to the 3D medical image from an intersection between the respective back-projection rays computed for each 2D X-ray image, thereby
• registering the registration phantom with the 3D medical image.

A method for registering a 3D medical image obtained by an X-ray imaging system with a registration phantom, wherein the registration phantom is positioned onto the patient and comprises a set of radiopaque fiducials having a known position in a coordinate system of said registration phantom, said set of radiopaque fiducials not being detectable in the 3D image, the method comprising:

• obtaining one 2D X-ray image acquired by the X-ray imaging system wherein at least three radiopaque fiducials of the registration phantom are detectable in said 2D X-ray image;
• registering said 2D X-ray image with the registration phantom by detecting and determining the position of the at least three radiopaque fiducials in the respective 2D image;
• computing for said 2D X-ray image, back-projection rays from the determined positions of said radiopaque fiducials in said 2D X-ray image based on a projection matrix of the X-ray imaging system;
• determining the position of each radiopaque fiducial on a respective back-projection ray based on the known position of said radiopaque fiducials in the coordinate system of the registration phantom, thereby determining the position of each radiopaque fiducial relative to the 3D medical image, thereby registering the registration phantom with the 3D medical image.

A method for registering a 3D medical image obtained by an X-ray imaging system with a registration phantom, wherein the registration phantom is positioned onto the patient and comprises a set of radiopaque fiducials having a known position in a coordinate system of said registration phantom, said set of radiopaque fiducials not being detectable in the 3D image, the method comprising:

• obtaining at least one 2D X-ray image acquired by the X-ray imaging system wherein at least three radiopaque fiducials of the registration phantom are detectable in each 2D image;
• for each obtained 2D X-ray image, registering the 2D X-ray image with the registration phantom by detecting and determining the position of the at least three radiopaque fiducials in the respective 2D image;
• determining the position of each of said at least three radiopaque fiducials relative to the 3D medical image based on the determined position of each of said radiopaque fiducials in each 2D X-ray image and on a projection matrix of the X-ray imaging system, thereby registering the registration phantom with the 3D medical image, wherein the 3D medical image is reconstructed from a set of 2D images acquired by the X-ray imaging system, and obtaining the at least one 2D X-ray image wherein at least three radiopaque fiducials of the registration phantom are detectable in each 2D image is implemented in an additional image acquisition after reconstructing the 3D medical image.