1. A method to assist with registering 3D data with 2D fluoroscopic images of a thorax of a patient comprising the steps of: receiving a 2D fluoroscopic image data set of the thorax including an anatomical structure which is visible under fluoroscopy; and approximating a candidate location of the anatomical structure based on the 2D fluoroscopic image data set; receiving a 3D data set of the anatomical structure in the thorax; and registering the 3D data set with the 2D fluoroscopic image data set based on the approximating step; wherein the 3D data set is at least one data selected from the group comprising image data and model data; and wherein the registering step comprises computing a 3D-projected location of the anatomical structure from the 3D data set, and matching the 3D-projected location of the anatomical structure from the 3D data set with the candidate location of the anatomical structure from the approximating step.