A medical data processing method for assisting the positioning of a first medical structure (1) relative to a second medical structure (2), the method being constituted to be executed by a computer and comprising the following steps: —acquiring two-dimensional projection image data comprising two-dimensional projection image information describing a two-dimensional projection image of at least the first medical structure (1) —acquiring registration data comprising registration information describing the registration of the two-dimensional projection image with respect to the first medical structure (1) —acquiring, on the basis of said two-dimensional projection image data, two-dimensional position data comprising position information describing the position of at least one base point (3) and at least one reference point (4) in the two-dimensional projection image —acquiring, on the basis of the two-dimensional position data, positional relationship data comprising positional relationship information describing the positional relationship between the at least one base point (3) and the at least one reference point (4) in the two-dimensional projection image —acquiring three-dimensional position data comprising position information describing the position of the at least one base point (3) and the at least one reference point (4) in three-dimensional anatomical space, in particular relative to the first medical structure (1) —determining, on the basis of the positional relationship data, the registration data and the three-dimensional position data, three-dimensional reference point correspondence data comprising correspondence information describing whether or not the position of the at least one reference point (4) corresponds to the position of the at least one reference point (4) in the two-dimensional projection image.
