%0 Conference Proceedings
%A Helou Neto, Elias Salomão,
%A De Pierro, Álvaro Rodolfo,
%T On the effect of relaxation in the convergence and quality of statistical image reconstruction for emission tomography using block-iterative algorithms
%B Brazilian Symposium on Computer Graphics and Image Processing, 18 (SIBGRAPI)
%E Rodrigues, Maria Andréia Formico,
%E Frery, Alejandro César,
%8 9-12 Oct. 2005
%J Los Alamitos
%I IEEE Computer Society
%K emission tomography, iterative algorithms.
%X Relaxation is widely recognized as a useful tool for providing convergence in block-iterative algorithms , , . In the present article we give new results on the convergence of RAMLA (Row Action Maximum Likelihood Algorithm) , filling some important theoretical gaps. Furthermore, because RAMLA and OS-EM (Ordered Subsets - Expectation Maximization)  are the algorithms for statistical reconstruction currently being used in commercial emission tomography scanners, we present a comparison between them from the viewpoint of a specific imaging task. Our experiments show the importance of relaxation to improve image quality.