CT Scatter Correction Based on Beam-hole Array and ADMM Algorithm

In cone-beam computed tomography (CT) systems, scatter signals can result in artifacts in images, thus adversely affecting image quality by reducing the contrast and signal-to-noise ratio. To accurately estimate and suppress scatter artifacts, a new scatter-correction method for cone-beam CT based on a beam-hole array (BHA) scatter-correction plate and the alternating direction method of multipliers (ADMM) are proposed. Based on the correction principle of the BHA scatter-correction plate, the plate is placed between the object under test and the detector during scanning. This setup captures projection data and computes scatter signals at the centers of the beam holes. Simultaneously, by incorporating the theory of compressed sensing, an L1-norm constrained model is established, and the ADMM is utilized to obtain a complete scatter-field distribution. Using an interpolation algorithm to scan angles reduces the time required for a full-angle reconstruction of the scatter field. Post-scatter removal and reconstruction yield scatter-corrected CT images. Data analysis of the reconstructed slices reveals the image quality, which indicates that the scatter-correction method based on the BHA plate effectively enhances the image contrast and reduces scatter artifacts. The improved scatter-signal reconstruction method further increases the accuracy of scatter-signal estimation, thus rendering scatter suppression more pronounced. Furthermore, using scanning-angle interpolation algorithms improves the efficiency of scatter-field reconstruction. The combined use of BHA and ADMM provides better scatter removal and further improvement in image quality.