Method and apparatus for generating a three-dimensional model of a region of interest using an imaging system

A method of generating a three-dimensional representation of a region of interest on a target object in an x-ray imaging system. The method uses a fiducial marker of known geometry. The region of interest and the fiducial marker are imaged in a plurality of predetermined positions. Expected images of the fiducial marker for each predetermined position are calculated and compared to captured images of the fiducial marker at each predetermined position. The difference between expected and captured imaged is used to generate corrected images of the region of interest for each predetermined position and these corrected images are used to generate a three-dimensional model of the region of interest. The method allows for the generation of useful three-dimensional models of a region of interest in an x-ray imaging system without requiring an expensive mechanical positioning system.