A method for correcting truncated projection data of a rotation for a reconstruction technique for computed tomography scans with truncated projection data in the computed tomography images produced by a C-arm is proposed. At least one truncated projection is recorded. The truncated portions prior to acquisition of the rotation for the at least one truncated projection is captured. The truncated projection and the truncated portions are assembled into at least one complete projection. Truncated projection data is acquired during the rotation. The truncated data is estimated based on a model of the patient geometry from the at least one complete projection. A reconstruction technique is performed on the basis of the acquired and the estimated data.