TY - JOUR T1 - NEMA NU 2 Performance Tests for Scanners with Intrinsic Radioactivity JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 822 LP - 826 VL - 45 IS - 5 AU - Charles C. Watson AU - Michael E. Casey AU - Lars Eriksson AU - Tim Mulnix AU - Doug Adams AU - Bernard Bendriem Y1 - 2004/05/01 UR - http://jnm.snmjournals.org/content/45/5/822.abstract N2 - Performance tests on lutetium oxyorthosilicate (LSO)–based PET scanners cannot be conducted strictly according to the National Electrical Manufacturers Association (NEMA) NU 2 standards because of the presence of intrinsic radioactivity within the LSO crystal scintillator material. This background radiation gives rise mainly to random coincidence events but also to a small number of true coincidences, which cannot be eliminated from measurements on such scanners and must therefore be corrected for in the data analysis. The current NU 2 standards do not take account of these backgrounds and hence can lead to erroneous results on LSO-based machines. Nevertheless, the intent of the standards can be met with appropriate modifications to the acquisition and processing procedures. In this paper, we propose certain changes to the NEMA specifications to accommodate this class of scanners. These changes affect mainly the estimation of sensitivity, scatter, randoms, and count losses. Using these modified procedures, the NU 2 performance of LSO-based systems can accurately be measured. ER -