Measurement of center of rotation for projection in X-ray two-dimensional computed tomography system

The determination of the center of rotation for projection is a very important step for the establishment of a X-ray two-dimensional computed tomography imaging system. The error of the center of rotation may lead to artifact in computed tomography image. In this work, the current popular measurement methods for the center of rotation are described and their advantages and disadvantages are reviewed, and a new method is thus put forward through analysis. The proposed algorithm is based on the laws: 'A particle is scanned a circle by computed tomography scanner, then the integral of the particle's projection address under each projection view equals to zero' and 'The sum of the coordinates of crossing points of projection sine curves of two random particles equals to zero'. The center of rotation for projection is determined by calculating the mean of projection address of the X-ray beam penetrating object. Compared with the current methods, the proposed algorithm needs no phantom and geometry parameter. The algorithm is real-time and has high measurement precision. The feasibility of the method is validated using the experiment results. ? 2010 SPIE.EI