| ICT(lndustrial Computed Tomography) started from the 1970's and gained rapid development in the 1980's. ICT has formed a relative independent technology domain now. ICT can detect gray image of the object's layer and does not destruct the object in the same time. ICT distinguish object layer's geometrical structure, material and defect type by gray. From 1980's ICT is applied widely. Many international industrial developed countries have applied ICT to nondestructive testing and reverse engineering in Aeronautics. ICT is not influenced by the object's material, shape and surface status, at the same time ICT may detect 2D image of object. At present ICT is considered the best method to nondestructive testing.At present, most of the ICT systems adopt FBP algorithm which need complete projections of data .In fact, complete projections of data is difficult or even impossible to acquire in many occasions .In this situation, the FBP algorithm is useless. The ART algorithm transfers this problem into finding the solutions of a linear equation group. When the projection data is incomplete, we can regard it as a linear equation group lacking of several equations The incomplete projection data is neglected to some extent, thus it can solve the problem very well. The disadvantages of ART algorithm are that it can not realize with hardware and the reconstruction speed is slowly. This paper has introduced some principals and reconstruction algorithms of ICT, ART algorithm is studied in detail. Furthermore, the influence factors of this algorithm are also studied and the simulation of ART algorithm has been carried out. Experiment has indicated that the ART algorithm may get better reconstruction results with the incomplete projection data. |
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