Determination of Spatial Resolution of Positron Emission Tomograph of Clear PET-XPAD3/CT System

Based on The National Electrical Manufacturers Association (NEMA), using the AMINE software to construction of sinograms and using a positron emission source of 22Na, were made calculations to determine the spatial resolution of a ring array system of phoswich detectors of positron emission tomograph included in the CLEAR PET-XPAD3/CT prototype for small animals, made in the laboratories of CCPM and whose project is led by the research group ImXgam. The radioactive source 22Na of approximately 9 MBq of activity, with spherical shape and diameter of 0.57mm is immersed in a plexiglas disc that was located at the geometric center of tomographic system with a Field of View (FOV) of 35 mm in the axial and transverse directions. Displacements of radioactive source were performed on the three cartesian axes and was rebuilt a sinogram for each axis. The shape of sinogram allows describe the correct position and the maximum efficiency of each detector. Subsequently, was carried out a scanning in each one of three spatial axes taking enough distance to cover the dimensions of radioactive source. Data for each phoswich detector were recorded. The process was repeated for other axes and then radioactive source was centered with respect to the FOV and were calculated FWHM (Full Width at Half Maximum) and FWTM (Full Width at Tenth Maximum) values and performing statistics of these values with parabolic fitting, the latter setting allows to obtain parameters of spatial resolution of system.