Abstract: Conventional image reconstruction of concbeam CI} usually assumes a cube or its inscribed cylinder as the reconstruction region, considering the characteristic of large difference of reconstruction objects of industrial CT in size, a fast image reconstruction method based on minimal cylindrical reconstruction region was proposed. Firstly, the envelope diagram of minimal region of reconstruction object was obtained by line scan conversion algorithm from concbcam projection data of different view. Then, the envelope of minimal region was determined by region filling algorithm. On this basis, the radius of minimal cylinder was obtained by midpoint circle algorithm. This method can adaptively determine the reconstruction region of minimal cylinder according to the size of reconstruction object, thus unnecessary computation is reduced. Experimental results show that the proposed method can effectively improve the reconstruction speed of algebraic reconstruction technique and obtain better reconstruction quality simultaneously.

Key words: Cone-beam CT, Image reconstruction, Reconstruction region, Algebraic reconstruction technique