Images registration & superimposition for dual resolution cone beam CT: a preliminary study

Registration and superimposition of images acquired from two different detectors is essential to dual-resolution cone beam CT. In this study we implemented and tested a method of integration, which is to register and superimpose the high resolution volume of interest (VOI) only images to the low resolution full field images. First, we acquired two images sets: One is low exposure low resolution full field images acquired with a low resolution detector; the other is high exposure high resolution volume of interest (VOI) images acquired with a high resolution detector and VOI mask. To locate the VOI positions in full field images, the third images set with VOI mask but without phantom was acquired with the low resolution detector. In the third images set, high contrast VOI boundaries were located and used to determine positions of the VOI in full field images. Then high resolution VOI images were superimposed with the full field images to generate integrated images set. Integrated images set was tested by subtraction from full field images set and then used to reconstruct images using regular FDK algorithm. In the reconstructed images, five Al wires (as small as 152 mu m) can be clearly seen in the VOI.