Center of rotation automatic measurement for fan-beam CT system based on sinogram image features.

For fan-beam X-ray CT system, projection center of rotation (COR) is one of the most important parameters which should be strictly controlled with high precision to ensure the accuracy of the image reconstruction. In our research, a novel method is proposed to locate COR for fan-beam CT system based on sinogram features. In this method, getting a data set with regular symmetric shape by averaging the original sinogram along the direction of column, and another data set by flipping the averaged data along the direction of row, the cross correlation operation is applied to these two data sets and finally the position of COR is determined by locating the peak values of the cross correlation function. In our proposed method, only the sinogram of the scanned slice is used for locating COR based on the image cross correlation without the calibration sample. The experimental results prove that it is easy to implement with high accuracy and anti-noise ability.