说明：  PARALLEL-BEAM TOMOGRAPHIC IMAGE RECONSTRUCTION This projects reproduces results of procedures regarding CT Image Reconstruction. The application will applied to computed tomography single photon emission (SPECT) data . In particular, the following steps-commands are used : reading / presenting two-dimensional sectional image data using function normalization volume [0,1] output intersection projections (imitonogramma - transformation radon 360 angles) using linear (linear) interpolation , projection filter (filter setting a cut-off frequency of the filter 90 of the maximum frequency), and the end use of iradon function for reconstruction. The results in the reconstructed images are compared on the basis of specific data line (improfile)