IEC 61675-3:1998 specifies test methods for describing the characteristics of gamma camera based wholebody imaging systems. As these systems are based on Anger type gamma cameras this part of IEC 61675 should be read in conjunction with IEC 60789. The test methods specified have been selected to reflect as much as possible the clinical use of gamma camera based wholebody imaging systems. It is intended that the test methods be carried out by manufacturers, thereby enabling them to describe the characteristics of gamma camera based wholebody imaging systems.