Method and device for making correction information available

A method for correcting a guidance direction of an instrument guided to a target point in an object during an examination, comprising:

• determining a first straight line indicating a current guidance direction of the instrument based on a current position on the instrument, the first straight line defined by a characteristic point on the instrument and a point on a tip of the instrument along a longitudinal axis of the instrument;
• determining a second straight line defined by the point on the tip of the instrument and the target point in the object, indicating a desired guidance direction of the instrument, wherein the point on the tip of the instrument comprises a common point of intersection between the first and second straight lines;
• defining a reference plane from the first and second straight lines, wherein both the first and second straight lines lie in the reference plane;
• computing correction information based on a relative position of the first and the second straight line that comprises an amount that the first straight line deviates from the second straight line relative to the common point of intersection in the reference plane, the correction information representing a required change from the current guidance direction of the instrument to the desired guidance direction of the instrument in order to reach the target point in the object;
• displaying a correction image comprising a projection image of the object with representations of the instrument having its tip inserted within the object, the first straight line indicating the current guidance direction, and the second straight line indicating the desired guidance direction of the instrument, the correction image acquired from a projection direction oriented perpendicular to the reference plane defined by the first and second straight lines, wherein the correction image provides a planar view of the reference plane,
• displaying on the correction image a correction diagram represented as two axes perpendicular to one another forming a 2D coordinate plane, the 2D correction diagram comprising the correction information, wherein an origin of the axes is positioned at a first point representing the intersection of the current guidance direction and the 2D coordinate plane such that the first straight line lies on a normal vector of the 2D coordinate plane, wherein the correction diagram provides an edge view of the reference plane from a position behind the instrument with a line of sight down the longitudinal axis of the instrument such that first straight line appears as a single point, and
• wherein a second point is displayed on the 2D coordinate plane representing the intersection of the desired guidance direction and the 2D coordinate plane, to visually assist correction of the current guidance direction of the instrument to the desired guidance direction based on the correction information.