Method and system for performing coordinate transformation for navigation-guided procedures utilizing an imaging tool and a position-determining system
Inventors
HOERNDLER KLAUS, null • Hörndler, Klaus • Fleischmann, Christof
Assignees
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Publication Number
US-8359085-B2
Publication Date
2013-01-22
Expiration Date
Abstract
The invention relates to a method and device for performing coordinate transformation for navigation-guided procedures using an imaging diagnostic tool, especially an X-ray diagnostic tool, and a position-determining system. In the vicinity of the image receiver, the diagnostic tool has one or more three-dimensional reference structure that can be touched with a pointer of a position-determining system. From the known geometry of the three-dimensional reference structure and the coordinates of the touched points determined by the position-determining system, a coordinate transformation is created between the coordinate system of the diagnostic tool and the coordinate system of the position-determining system. Navigation for an instrument captured by the position-determining system can be performed in reconstructed images of the diagnostic tool after the registration procedure.
Core Innovation
The invention relates to a method for performing coordinate transformation in navigation-guided procedures between an imaging diagnostic tool with at least one reference structure and a position-determining system. The reference structure is positioned adjacent to the imaging diagnostic tool and comprises a plurality of truncated pyramid-shaped recesses with known surface geometry and orientation relative to the imaging diagnostic tool. A pointer with markers detectable by the position-determining system traces the reference structure by contacting three or more contact points that form a non-isosceles triangle.
The position-determining system determines the coordinates of the contacted points in its coordinate system and transmits these coordinates to an evaluation computer of the imaging diagnostic tool. The imaging diagnostic tool assumes an orientation substantially insensitive to the effect of mechanical forces during tracing, and adjustment axes of the imaging diagnostic tool are locked such that the kinematics of the imaging diagnostic tool are predicted as a function of an ordered series of measurement values of position sensors located on the imaging diagnostic tool.
The method recursively transforms the coordinate systems of the position-determining system and the imaging diagnostic tool into one another with a transformation matrix. The transformation matrix is calculated by a computer program in the evaluation computer from the coordinates of the contacted points in the coordinate system of the position-determining system and from the known surface geometry of the reference structure in a coordinate system of the imaging diagnostic tool, and navigation of an instrument is performed in reconstructed images after registration.
Claims Coverage
The independent claim identified is clm-00001, with one main inventive feature set centered on tracing a reference structure with a pointer and recursively computing a transformation matrix between coordinate systems while mitigating mechanical-force effects. The partial content also describes dependent refinements involving specific pointer-tip/reference geometry, contact-force limits, sterile cover film handling, validity until excessive adjustment, and time-windowed capture after electrical contact detection.
Positioning a reference structure with known surface geometry and truncated pyramid-shaped recesses
Positioning the at least one reference structure adjacent to the imaging diagnostic tool, wherein the at least one reference structure comprises a plurality of truncated pyramid-shaped recesses.
Tracing the reference structure with a pointer tip using marker detection and a non-isosceles triangle
Tracing the at least one reference structure by contacting it with the tip of a pointer at three or more contact points forming a non-isosceles triangle, wherein the tip of the pointer has markers that can be detected by the position-determining system.
Determining and transmitting contacted point coordinates for evaluation
Determining the coordinates of the contacted points by the position-determining system in a coordinate system of this position-determining system and transmitting them to an evaluation computer of the imaging diagnostic tool.
Mechanical-force-insensitive imaging diagnostic tool orientation with locked adjustment axes
The imaging diagnostic tool assumes an orientation substantially insensitive to the effect of mechanical forces during tracing, and adjustment axes of the imaging diagnostic tool are locked such that the kinematics of the imaging diagnostic tool are predicted as a function of the ordered series of measurement values of position sensors located on the imaging diagnostic tool.
Recursively transforming coordinate systems via a transformation matrix from contacted points and known geometry
Recursively transforming the coordinate systems of the position-determining system and the imaging diagnostic tool into one another with a transformation matrix, wherein the transformation matrix is calculated from the coordinates of the contacted points in the coordinate system of the position-determining system and from the known surface geometry of the reference structure in a coordinate system of the imaging diagnostic tool, by a computer program in the evaluation computer.
Hemispherical recess pointer-tip pivoting with cone-envelope longitudinal axis tracking
Determining the coordinates of the tip of the pointer ball during pivoting with the position-determining system, wherein the reference structure comprises hemispherical recesses that substantially conform to the tip of the pointer to pivot the pointer tip and guide a longitudinal axis of the pointer along a section of a cone envelope.
Contact-force limited coordinate determination of the pointer tip
Determining the coordinates of the pointer tip with the position-determining system while the pointer tip is pressed onto the reference structure, wherein the contact force is constrained to a given upper limit and a given lower limit.
Sterile cover film crease and thickness handling for transformation matrix computation
Determining the coordinates of the tip of the pointer by the position-determining system after visual inspection of a sterile cover film for creases at the contact point and incorporating the thickness of the film into the calculation of the transformation matrix.
Transformation validity until detection of excessive imaging diagnostic tool adjustment
Keeping the coordinate transformation valid until a controller detects that the imaging diagnostic tool has been adjusted beyond its designed adjustment area.
Time-windowed coordinate determination immediately after electrical contact detection
Determining the coordinates of the pointer tip by the position-determining system in a time window immediately after detecting an electrical contact between the tip of the pointer and the reference structure.
Across the independent claim and the extracted dependent refinements, the inventive concept centers on tracing a reference structure with a pointer whose markers are detected by a position-determining system, transmitting contacted-point coordinates to an evaluation computer, and recursively computing a transformation matrix that aligns coordinate systems of the position-determining system and the imaging diagnostic tool using known reference geometry. The refinements emphasize specific reference and pointer contact geometries, mechanical-force insensitivity via locked adjustment axes, and constraints and validity limits related to contact force, sterile cover film effects, excessive tool adjustment detection, and timing relative to electrical contact detection.
Stated Advantages
Substantially insensitive orientation of the imaging diagnostic tool to the effect of mechanical forces during tracing.
Improved accuracy by calculating the transformation using known surface geometry together with contacted-point coordinates and by using locking and predicted kinematics based on position sensor measurement values.
Reduced sensitivity to mechanical-force effects during tracing of the reference structure.
Improved accuracy via multiple tip observations during pointer pivoting or traversal paths on the reference structure.
Higher robustness by constraining coordinate determination to contact-force limits and to a time window immediately after electrical contact detection.
Improved accuracy by handling sterile cover film thickness and creases at the contact point.
Controlled transformation applicability by keeping it valid until a controller detects adjustment beyond a designed adjustment area.
Documented Applications
Navigation of an instrument in reconstructed images after registration following coordinate transformation.
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