System matrix calculation for Clear-PEM using ART and linograms

The Clear-PEM device is a positron emission mammography (PEM) unit based on planar detectors and is currently under development. We have developed a 2D algebraic reconstruction technique (ART) algorithm using linograms to reconstruct Clear-PEM data. In this work we evaluate three different methods of calculating the system matrix used by the ART algorithm, which we designate as the pixel-, ray- and tube-driven methods, respectively. The methods were tested using Monte Carlo simulated data. The results obtained show that ART algorithm allows, for these cases, accurate image reconstruction and indicate that a more accurate modeling of the image system matrix using tubes of response (TORs) provides the best image evaluation indexes.