The algebraic reconstruction technique (ART) is an iterative reconstruction technique used in computed tomography. It reconstructs an image from a series of angular projections (a sinogram). Gordon, Bender and Herman first showed its use in image reconstruction; whereas the method is known as Kaczmarz method in numerical linear algebra. An advantage of ART over other reconstruction methods (such as filtered backprojection) is that it is relatively easy to incorporate prior knowledge into the reconstruction process. ART can be considered as an iterative solver of a system of linear equations A x = b, where: Given a real or complex matrix A and a real or complex vector b, respectively, the method computes an approximation of the solution of the linear systems of equations as in the following formula, where, a_i is the i-th row of the matrix A, b_i is the i-th component of the vector b. \lambda_k is an optional relaxation parameter, of the range. The relaxation parameter is used to slow the convergence of the system. This increases computation time, but can improve the signal-to-noise ratio of the output. In some implementations, the value of \lambda_k is reduced with each successive iteration. A further development of the ART algorithm is the simultaneous algebraic reconstruction technique (SART) algorithm.