System and methods for fast and robust determination of the 3d position of an object based on a medical image and a 2d-2d matching procedure

A system configured for determining a position of an anatomy in a 3D image coordinate system based on an X-ray image, the system being configured to perform the steps of

• receiving the X-ray image depicting the anatomy,
• receiving a first plurality of virtual X-ray images, wherein the virtual X-ray images of the first plurality of X-ray images are generated as projection images of a 3D data set of the anatomy with a first distribution of different imaging directions,
• identifying image features in the received X-ray image,
• identifying image features in the virtual X-ray images of the first plurality of virtual X-ray images,
• performing a comparison of the image features of the virtual X-ray images of the first plurality of virtual X-ray images with the image features of the X-ray image by applying at least one out of the group consisting of image rotation, image zoom, translating within the image plane, for determining one of the virtual X-ray images of the first plurality of virtual X-ray images which provides a best match of the image features with the image features in the received X-ray image, wherein the determined virtual X-ray image of the first plurality of virtual X-ray images is utilized for determining an approximation of the position of the anatomy.