*Corresponding author: Dr. S. Rasoul Zakavi, Nuclear Medicine Research Center, Emam Reza Hospital, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Fax: +98 511 8419521 E-mail: Zakavir@mums.ac.ir Background: 99mTc is a widely used radioisotope in nuclear medicine centers which is obtained by elution from Mo-99/Tc-99m generators. Usually the generators are either suppli...