Scatter Correction Study For CT Image Of Aviation Turbine Blades

The NDT(Nondestructive Testing)of aviation turbine blades is crucial technology for blade manufacturing and maintenance.Coloring,infrared heat wave,ultrasonic and so on are usually used to test turbine blades,but these methods are unable to detect turbine blade interior well.With the development rapidly of CT(Computed Tomography),it has been widely used in medical,industry,biology,chemistry and so on,and also be used to detect turbine blades gradually.CT has higher precision,better imaging quality,stronger defect recognition ability compared with other testing methods for turbine blades.Because Micro-CT has smaller focus and detector pixel than traditional CBCT(Cone beam Computed Tomography),it has higher testing precision.But the low X-ray energy of Micro-CT and high density of the turbine blade will lead to product artifacts on CT images,and most of these artifacts caused by Compton scatter.So it has to be corrected to acquire high quality reconstructed images.BSG(Beam Stop Grid)is used to conduct scatter correction study for Micro-CT images of turbine blades in this paper.BSG scatter correction blocker is composed by full coverage lead strips and needs twice scan,it can achieve correction by combine two group projection data.To improve detection efficiency for turbine blades using BSG,an improvement correction method based on BSG is proposed,it just needs once scan accomplishing scatter correction by improve the design of correction blocker and reconstruction algorithm.The lead of blocker is distribution in stagger style,and the reconstruction algorithm is improved based on traditional FDK algorithm to adapt projection of single scan.The projection is divided into left and right two parts to reconstruct CT images,and then combine the CT image using a weight function.There are many details on coronal and axial CT images blurred by artifacts are restored with BSG and single scan scatter correction.The contrast and CNR(Contrast-Noise-Ratio)of CT images corrected by BSG and single scan have significantly increasing than CT images without correction,and the value corrected by single san is better than BSG.If using TV regularization for corrected CT images,the image quality will be improved further.All results show that the scatter correction using single scan based on BSG is useful for Micro-CT image of turbine blades.