The application of X-ray beam hardening correction based on polynomial fitting in local scan

2 national X ray digital imaging center; Mianyang,China Abstract Beam Hardening effect would be induced due to broad energy spectrum of X-ray. Beam Hardening would lead to artifacts in CT reconstructed images, such as cupping artifact, streak artifact and metal artifact, so that the quality of CT image degrades. One efficient beam hardening correction method is building a mathematical law between polychromatic projection and intersection length, which can be calculated by forward projection in reconstructed images domain. However, to local scan, the intersection length obtained by forward projection is no longer equal to the real distance which X-ray passes through the object. The data used to mathematical fit is not valid. A cylindrical phantom was used in this paper. According to geometrical character of cylinder, the true distance X-ray passing through the object could be calculated analytically. Experimental result showed the beam hardening artifacts were suppressed by our approach.