Study On X-Ray CT Imaging Methods For Pipelines

X-ray computed tomography(CT)is a non-invasive and non-destructive testing technology which can reconstruct the internal structure image of an object based on external projection data.The obtained image has high resolution and is also easy to be processed on computer.Besides,X-ray CT is able to detect various pipelines with non-destructive method and acquire their corrosion status and weakness,in order to keep pace with the quality change rule.However,the X-ray emitted by the light source cannot penetrate the highly absorbed objects,such as high-density copper pipelines,resulting in the lack of projection data in the corresponding region,which makes it difficult to directly reconstruct high-quality images.Aim at the corrosion detection of metal pipelines,it is of great significance for engineering applications to improve a reconstruction method that can eliminate artifacts and obtain high quality images which meet the actual needs.When the projection data is incomplete,the traditional Filtered-BackProjeciton algorithm reconstructs the image containing a lot of artifacts,which seriously affects the image quality.Iterative algorithm can suppress artifacts better and has obvious advantages in reconstruction with incomplete projection data.This paper focuses on the problem of image reconstruction from incomplete projection data of X-ray CT.Taking corrosion detection of seawater pipelines as an example,we studied the problem of X-ray penetrating metal materials,and we proposed a CT reconstruction method based on iterative algorithm.The main contents include:interpolation method of CT projection data and CT imaging method of copper seawater pipeline.Considering the projection data truncation in every angle,the CT scanning model of pipeline has been designed.Truncated data is filled up by interpolation,and a kind of grouped ART iterative algorithm based on TV with weighted mean processing is proposed.The image after iterative reconstruction is processed by image segmentation and smoothing tec.