Calculation of the rotational centers in computed tomography sinograms

An efficient method for accurate calculation of the center-of-rotation, or projection center, for parallel computed tomography projection data, or sinograms, is described. This method uses all the data in the sinogram to estimate the center by a least squares technique and requires no previous calibration scan. The method also finds the object center-of-mass without reconstruction of its image. Since it used the measured data, the method is sensitive to noise in the measurements, but that sensitivity is relatively small compared to other techniques. Examples of its use on simulated and actual data are included. For fanbeam data over 360 degrees, two related methods are described to find the center in the presence or absence of a midline offset