Patent EP-3747387-A1 (EP)
Title: Wrong level surgery prevention
Inventor: ESSENREITER ROBERT
IPC: A61B34/20
Filed: 2013-07-19
Abstract: The invention relates to a method of relating a position (pos(selected)) of an anatomical structure (3) and a position of an image feature representing the anatomical structure in a medical image (11), the method being constituted to be executed by a computer and comprising:a) acquiring, by tracking, with a medical navigation system, a marker device (4) having a fixed spatial relationship relative to a medical imaging apparatus (1) being a CT scanner or a single x-ray tube, information about the position of the medical imaging apparatus (1) at the beginning (pos(start)) and at the end (pos(end)) of acquiring medical image information describing a medical image (11) of at least a part of a patient's body (2) comprising the anatomical structure (3), wherein the medical imaging apparatus (1) is moved while it is used for acquiring the medical image information;b) acquiring imaging information about a relationship between the movement of the medical imaging apparatus and the acquisition of the medical image information;c) acquiring, based on the position of the medical imaging apparatus at the beginning (pos(start)) and at the end (pos(end)) of acquiring the medical image information, information about a predominant direction of movement (z) of the medical imaging apparatus (1);d) acquiring, by tracking, with the medical navigation system, a marker device (13) having a predetermined spatial relationship relative to a pointer (12), information about the position (pos(selected)) of the pointer (12) in the predominant direction of movement (z), wherein the pointer (12) is pointed at the anatomical structure (3);e) determining, based on the information about the position of the medical imaging apparatus (1) at the beginning (pos(start)) and at the end (pos(end)) of acquiring the medical image information and based on the information about the position (pos(selected)) of the pointer means (12) and based on the imaging information, information about a transformation between the position (n<sub>s</sub>) in the medical image (11) of an image feature representing the anatomical structure (3) and the position of the anatomical structure (3) in a navigation reference system (17), wherein the transformation is defined by the following relations:zselected=ns/nx−1⋅zend−zstartwhere: z(selected) is the value of the coordinate component of the position of the marker device (4) having a predetermined spatial relationship relative to the medical imaging apparatus (1) in the predominant direction of movement;n<sub>s</sub> is the number of the set of image units (representing the image information taken at the point in time at which the z-position of the medical imaging apparatus is z = z(selected), wherein n<sub>s</sub> defines the position in the medical image (11) of the image feature representing the anatomical structure (3);n<sub>x</sub> is the total number of sets of image units along the predominant image direction;z(start) is the value of the coordinate component of the position of the medical imaging apparatus (1) in the predominant direction of movement which it has at the beginning of taking the medical image information; andz(end) is the value of the coordinate component of the position of the medical imaging apparatus (1) in the predominant direction of movement which it has at the end of taking the medical image information; andposselected=posend+zselected−zend/zend−zstart⋅posend−posstart/‖posend−posstart‖ where:pos(selected) is the position of the pointer (12) at which its coordinate component in the predominant direction of movement is z(selected);pos(start) is the position of the medical imaging apparatus (1) which it has at the beginning of taking the medical image information;pos(end) is the position of the medical imaging apparatus (1) which it has at the end of taking the medical image information; and∥ ∥ is a norm operator which is applicable to the navigation reference system (17).