Abstract：An artifact is usually regarded as a measure error，but the boundary artifact is an exception，which occurs in the interface between two different media. As a kind of systematic errors caused by reconstruction algorithm of CT images，the boundary artifact contains some information of the sample size. Based on conventional back-projection reconstruction algorithm of CT image，the mechanism of CT boundary artifacts is analyzed. The study shows that the sample boundary is in correspondence with the position of CT boundary artifact maximum and the study on boundary artifact is beneficial to correctly judge the position of sample in CT image and evaluate the geometrical dimension of sample.
