Principles of image reconstruction using Positron Emission Tomography and maximum likelihood estimation algorithms

Positron Emission Tomography (PET) is used extensively in image acquisition for medical purposes. It is necessary to perform an evaluation of parameters that are required for image reconstruction based on the measured data. The most commonly used method for estimation of PET parameters is Expectation Maximization algorithm. About a decade ago a new SAGE algorithm was developed and soon it began to be used in image reconstruction. Principles and examples of these algorithms as well as of PET are described in this paper.