"An individual software program or group of programs, routines or algorithms that add specific image processing and/or analysis capabilities to a single photon emission computed tomography (SPECT) imaging system configuration. A basic set of applications programs and routines is included with such computer-controlled imaging systems and they can be upgraded to correct programming errors or to add new system capabilities. Some packages must be combined with specific hardware or firmware configurations in order to function as intended. Applications program packages are typically identified by a proprietary name and ""version"" or ""upgrade"" number."