Hellenic Journal of Nuclear Medicine May-August 0 www.nuclmed.gr   Abstract The main objective of this work was to show that a gamma camera in a developing country could perform eiciently despite electricity outages using intrinsic lood uniformity tests as an index of performance. A total of 143 intrinsic uniformity test results for a new gamma camera in use in an envi- ronment with unstable power supply are presented. The integral uniformity for the central ield of view (CFOV) was found to be between 3.43% and 1.49% (3.29% for acceptance test) while the integral uniformity for the useful ield of view (UFOV) was between 4.51% and 1.9% (5.21% for acceptance test). The diferential uniformity for the CFOV was between 1.99% and 1.04% (2.25% for acceptance test) while that of the UFOV was between 2.84% and 1.23% (2.63% for acceptance test). In conclusion, these results show that the uniformity of the gamma camera under this condition is within an ac- ceptable range for both planar and SPET imaging. Introduction Τ he intrinsic lood uniformity test of a gamma camera is a measure of the response of the gamma camera to a uniform lux of radiation from a point source when the collimator is removed. It is one of the primary tests performed on the gamma cam- eras [1]. It is also one of the indices used to measure the performance of a gamma camera. Intrinsic lood uniformity test is a part of the quality assurance programme of a nuclear medicine department that ensures high standards of eiciency and reliability in the use of a gamma camera. We thus avoid changes in the performance of a gamma camera system that might afect the interpretation of clinical studies [2]. Two diferent uniformity parameters, usually measured during this test are: integral uni- formity and diferential uniformity. These are calculated for both the central ield of view (CFOV) and useful ield of view (UFOV) of the gamma camera. The integral uniformity has typical values of 2% to 4% [3]. For diferential uniformity in most cases, a value of less than 3% is obtained after uniformity correction [4]. When the value for diferential uniformity exceeds 3%, maintenance service should be carried out on the gamma camera [5]. Values of diferential uniformity in the range 1.0% to 2.5% and values of integral uniformity in the range of 1.5% to 3.5% when the uniformity correction is applied are an indication that the system is working well. Generally, between 10 to 30million count lood images are ad- equate for veriication of non uniformity of the system, for all clinical studies. For routine planar imaging with a gamma camera, small luctuations in ield uniformity are allowed but for single photon emission tomography (SPET), the demand for uniform- ity is higher. So high quality lood (30 to 100 million counts) to prevent the occurrence of circular artifacts in the inal SPET image are suggested to be acquired [6]. The main aim of this research is to show that a gamma camera in a developing country could perform eiciently despite electricity outages. Thus, we have investigated the per- formance of our gamma camera using intrinsic uniformity as the index of performance. This study covers a period of two years (2006–2008). Materials and methods The gamma camera used is the Siemens e.cam (signature series) SPET system with single head (Siemens Medical Solutions U.S.A, Inc.) which was installed at the center in March, 2006. The camera set up for the lood uniformity test is as in Figure 1. A point source of technetium-99m pertecnetate ( 99m TcO - 4 ) of activity ranging from 0.74MBq to 3.7MBq was Gamma camera intrinsic uniformity in an unstable power supply environment Hell J Nucl Med 2011; 14(2): Published on line: 16 June 2011 Technical Note