The Study Of Scanning For The Strainght-Line Trajectory Tomography

Computed tomography is a imaging which get different angles of projection data,andthen use the image reconstruction algorithm to obtain the information of the section of theobject.However,in industrial CT inspection,there are some objects which have large-size flatplate or curved plate structures(such as arc-shaped casting,sheet metal welded together,etc),these length,width may be a few meters or even tens of meters,but the thickness,only a fewcentimetre to tens of centimetre,so using the traditional CT scanning clear can not,they mustbe used a special scanning method to solve the detection.So in this paper,I will propose a newtomography system based on straight-line trajectory scanning. The new tomography controlits mechanical design is simple,do not need for objects to rotate,only need for objects to dothe simple uniform motion through the radiation field;This method has fast imaging,they don'thave overlap between the issues such as the fault.Sheet structure for large objects,comparedwith spiral trajectory scanning and circular trajectory scanning,the straight-line trajectoryscanning has more advantages.The straight-line trajectory scanning obtain incomplete projection data,it belong to limitedangles of image reconstruction.The projection matrix of straight-line trajectory scanning hasthe large storage capacity and long operation,so it is not conductive to computing.To reducethe storage capacity,in this chapter,I depicts two method of the projection matrix under thestraight-line trajectory scanning,and use of the ART iterative algorithm to simulate projectionand reconstruction of their.The results of reconstruction have artifact,so in this paper,I propose two methods to remove the artifact. Base on this,for the image size beyond the scope ofradiation field,and combined with ART iterative algorithm and Conjugate Gradientalgorithm(FRCG),I propose ART-FRCG hybrid algorithm,which is more suitable for theimage size beyond the scope of the X-ray field,and it has strong noise resistance;Finally,wecan obtain the actual projection data by the straight line trajectory scan,and can bereconstructed by ART or ART-FRCG,the result can be explain that straight-line trajectory scancan obtain the fault of the image of the object.