Method and device for navigation of a surgical tool

A method of navigation of a linear instrument to be used in a surgical intervention for treating a target region within the body of a patient, comprising

• detecting by an imaging system an image position of a reference marker disposed on the body of the patient in a vicinity of an entry point corresponding to a point through which the linear instrument should be inserted for reaching the target region, and detecting a spatial position of said reference marker by a localizing system,
• calculating a transform matrix between an image coordinate system of the imaging system and a spatial coordinate system associated with the reference marker by using detected image and spatial positions of the reference marker, in order to register data of the localizing system and imaging system together,
• applying a correction matrix to said transform matrix so as to determine a corrected transform matrix,
• wherein said correction matrix is computed by the following steps:
• obtaining image data of a zone of the body of the patient with the imaging system, said zone including the target region to be treated and at least a part of the linear instrument;
• displaying a real position of said part of the linear instrument as a linear trace visible on the image data;
• determining a virtual position of the linear instrument with the localizing system using a magnetic tracker attached to the linear instrument or to a guide of the linear instrument;
• and
• computing the correction matrix so as to make a position of the linear instrument on a navigation image correspond to a position of a selected linear shape using said linear trace and said virtual position;
• detecting a spatial position of the linear instrument determined by the localizing system;
• and
• constructing and displaying the navigation image, wherein a representation of the spatial position of the linear instrument is displayed on said image data from the imaging system using the corrected transform matrix.