shabnam oloomi department of medical physics, mashhad university of medical science, mashhad, iran hadi noori eskandari department of applied mathematics, school of mathematical sciences, ferdowsi university of mashhad, mashhad, iran seyed rasoul zakavi nuclear medicine research center, imam reza hospital, faculty of medicine, mashhad university of medical sciences, mashhad, iran peter knoll department of nuclear medicine wilhelminenspital vienna, austria faraz kalantari research center for nuclear medicine, tehran university of medical sciences, tehran, iran mohsen hajizadeh saffar department of medical physics, mashhad university of medical science, mashhad, iran