A correction algorithm for detector nonuniformity in computed tomography

In actual computed tomography systems, detector nonuniformity can result in obvious concentric circles in reconstructed images and it is very important to correct it. Although nonuniformity can be corrected by current methods, residual nonuniformity still exists after correction. To resolve this problem, we have designed an effective correction algorithm based on the geometrical relationships in tomographic data. The proposed method consists of two steps, edge detection and correction. In the first step, detectors to be corrected are located using multiscale wavelet analysis. In the second step correction is implemented for these detectors. This algorithm is implemented after ordinary correction and can correct residual nonuniformity effectively. Promising results are achieved in our experiments.