关键词: X射线成像, 复杂结构件, 轮廓约束, 先验信息

Abstract: In the X-ray CT imaging inspection system,due to the complicated structure of complex shaped workpieces,scattering,hardening and other phenomena are more serious.At some projection angles,due to the large difference in effective thickness in the ray transillumination direction,the fixed energy ray dose does not match the thickness,the quality of the projection data is poor,the reconstructed image obtained by the traditional CT reconstruction algorithm is of low quality,the edges are blurred,and the complete contour information of the workpiece cannot be obtained.In this paper,a CT imaging method for complex shaped workpieces based on contour prior constraints is studied.Firstly,the binocular stereo vision technology is used to obtain the contour information of the workpiece,and the registration of the a priori image is completed according to the spatial positional relationship between the binocular coordinate system and the CT coordinate system.The contour prior is then incorporated into the CT reconstruction process and contour constrained reconstruction is performed in conjunction with TV (Total-variation) regularization.The experimental results show that the proposed method can effectively suppress artifacts and noise,preserve the edges of reconstructed images,improve the quality of reconstructed images,and improve the reliability of defect detection of complex shaped workpieces.

Key words: X-ray imaging, complex structural parts, contour constraint, prior information