Method and system for correction of fluoroscope image distortion
View Patent ↗Certain embodiments of the present invention provide for a system and method for modeling S-distortion in an image intensifier. In an embodiment, the method may include identifying a reference coordinate on an input screen of the image intensifier. The method also includes computing a set of charged particle velocity vectors. The method also includes computing a set of magnetic field vectors. The method also includes computing the force exerted on the charged particle in an image intensifier. Certain embodiments of the present invention include an iterative method for calibrating an image acquisition system with an analytic S-distortion model. In an embodiment, the method may include comparing the difference between the measured fiducial shadow positions and the model fiducial positions with a threshold value. If the difference is less than the threshold value, the optical distortion parameters are used for linearizing the set of acquired images.
1. A method for calibrating an image acquisition system with an analytic S-distortion model, said method comprising:
(a) acquiring a set of images, wherein said images include patient anatomy and fiducial markers embedded within a calibration target;
(b) processing said images to obtain measured fiducial markers shadow positions in imaging plane coordinates;
(c) estimating image acquisition system intrinsic parameters, image acquisition system extrinsic parameters, and optical distortion parameters based on the measured fiducial markers shadow positions;
(d) computing a set of model fiducial markers positions in an imaging plane based on the estimated image acquisition system intrinsic parameters and image acquisition system extrinsic parameters;
(e) correcting for the S-distortion and pincushion distortion of the measured fiducial markers shadow positions;
(f) computing the difference between the measured fiducial markers shadow positions and the model fiducial positions;
(g) comparing the difference between the measured fiducial shadow positions and the model fiducial positions with a threshold value, if said difference is greater than the threshold value, the image acquisition system intrinsic parameters, the image acquisition system extrinsic parameters, and the optical distortion parameters are updated and used as input for step d) in the next iteration cycle;
(h) if said difference is less than the threshold value, the optical distortion parameters are used for linearizing said set of acquired images.
2. The method of claim 1 , wherein said image acquisition system intrinsic parameters include focal length, piercing points, and scaling factor.
3. The method of claim 1 , wherein said image acquisition system extrinsic parameters include calibration target fiducial positions.
4. The method of claim 1 , wherein said optical distortion parameters include field attenuation coefficients.