A motion estimation and compensation algorithm for 4D CBCT of the abdomen

We propose an algorithm for periodic motion estimation and compensation in the case of a slowly rotating gantry, e.g., as is the case in cone beam CT. The main target application is abdomen imaging, which is quite challenging because of the absence of high-contrast features. The algorithm is based on minimizing a cost functional, which consists of the data fidelity term, the optical flow constraint term, and regularization terms. To find the appropriate solution we change the constraint strength and regularization strength parameters during the minimization. Results of experiments with simulated and clinical data demonstrate promising performance.