To solve the problem of slow reconstruction speed of algebraic reconstruction technique

this paper presents a fast traversal and intersection algorithm of ray beam-pixels. The algorithm determines the pixel index traversed by ray beam and calculates area overlapped by the ray beam through a distance parameter. The distance parameter can be calculated with an incremental method

thus the operation is of high efficiency. Applying this algorithm to calculate the weight coefficients on real-time during the process of reconstruction

not only large amount of memory is saved

but also the speed of image reconstruction is improved greatly. The experimental result shows that the algorithm is very effective and the reconstruction speed is improved about 17 times compared with the conventional method.