Method of three-dimensional device localization using single-plane imaging
View Patent ↗A method and system for determining the three-dimensional location and orientation of a medical device distal end using a single-plane imaging system, using a computational model of the medical device and a transfer function for the medical device describing local device shape and orientation in response to user or computer determined inputs. The method allows guidance of an interventional medical system to a set of target points within the patient using a single-projection imaging system.
1. A method of estimation of three-dimensional localization information for a medical device distal end utilizing a two-dimensional X-ray projection image, the method comprising:
identifying the three-dimensional location of a base point from which a length of medical device bends, and a three dimensional orientation vector for the device at the base point;
defining a bending plane in which the medical device is contained;
identifying the location and orientation of the end of the medical device as projected onto a X-ray projection image;
determining a line between the X-ray source and X-ray imaging plane for use in estimating the three-dimensional location of the end of the medical device;
defining an expected two-dimensional orientation of the end of the medical device projected onto the X-ray projection image, as a function of the length of the medical device;
determining a value of the length of the medical device that minimizes the deviation between the identified two-dimensional orientation of the end of the medical device as projected onto the X-ray projection image and the expected two-dimensional orientation calculated as a function of the length of the medical device; and
determining a point on the line between the X-ray source and X-ray imaging plane that minimizes the distance between the line and a three-dimensional location of the end of the medical device calculated as a function of the selected value of the length of the medical device, to obtain a refined estimated three-dimensional location of the end of the medical device.
2. The method of claim 1 , wherein the method for estimation of the three-dimensional location of a medical device is utilized in a feedback control algorithm for improving accuracy in navigating the end of a medical device to a target area within a subject body.
3. The method of claim 1 wherein the expected two-dimensional orientation of the end of the medical device is further calculated as a function of the device's mechanical properties.
4. The method of claim 3 wherein the mechanical properties include the modulus of elasticity, the bending moment of inertia, and the length of the bend in the medical device.
5. The method of claim 1 wherein the two-dimensional x-ray image is a projection image in an x-ray imaging system.
6. The method of claim 1 wherein the method of estimation comprises using a transfer function for the medical device.
7. The method of claim 6 wherein the transfer function relates output parameters comprising local shape and local orientation at a number of points along the device to input parameters comprising pull wire tensions.
8. The method of claim 6 wherein the transfer function relates output parameters comprising local shape and local orientation at a number of points along the device to input parameters comprising magnetic field distributions.
9. The method of claim 6 wherein the transfer function relates output parameters comprising local shape and local orientation at a number of points along the device to input parameters comprising applied voltages.