Cone-beam CT Data-Driven Pose Correction forAnalytic Reconstruction Methods

摘要

A precise knowledge of the geometry information of a cone-beam CT is required for high quality image reconstruction. In some applications, however, the acquisition geometry is either not well characterized or not repeatable, for example, in the case of gantry vibration and patient motion. An offline correction using a calibration pattern and an online calibration using an external tracking system may be used to measure and correct CT geometry parameters during reconstruction. Both approaches have limitations though. A new method is proposed in this paper to estimate pose parameters using the acquired cone-beam projection data only. During the pose estimation process each 2D projection data is registered to the 3D volume reconstructed from the current, inaccurate pose estimate. Pose parameters are then corrected incrementally using the registration results. Applying this 2D-3D registration method to the FDK reconstruction method, we are able to estimate rotational parameters to within an average total angular deviation of 0.5 degrees, and center-of-rotation to an average of 0.02% of the source-to-detector distance (SID) in the detector plane. The image quality of CT reconstructions is comparable to those using exact geometry.