Abstract: Affected by the precision of instruments and other factors, CT turntable may cause the
deviation of projection center of rotation (COR), which will seriously affect the quality of the
reconstructed images. Thus, the precise correction of COR in projection images plays an important
role in the CT reconstruction. In this paper, a method of measuring the address of COR is proposed
based on the radon transform, which is suitable for the parallel beam scanning model. The method can
be summarized as follows: the COR address of the projection is obtained using one half of the mean
of the 0° and 180° projections’ addresses in sinogram. According to the method, the data, which
represent 0° and 180° projections in sinogram, were respectively copied by N times to get the image
matrix A. The image matrix A was then segmented into binarization with the “Chan-Vese” method,
and the 0° and 180° projections’ addresses of sample were obtained to calculate the COR address of the
projection. Finally, the COR value was regarded as the center of the sinogram, and the sinogram was
clipped properly in the horizontal direction. The simulation and experiment show that this method can
accurately correct the COR, which effectively improves the quality of the reconstructed images. method
can accurately correct the COR, which effectively improves the quality of the reconstructed images.

Key words: CT reconstruction, sinogram, center of rotation, binary segmentation, correction