1. A method to calibrate a mechanical model of behaviour and movement of an interventional radiology table, the method comprising the steps of: moving the table over at least one degree of freedom; acquiring at least one set of images corresponding to different positions of the table and C-arm; obtaining at least one set of images of a test object from different positions; using the images of the test object to determine parameters of the mechanical model of table behaviour and movement; combining these parameters with data given by table movement sensors so as to deduce the true relative positions of the table with respect to the medical imaging system.