In this thesis several aspects related to the quantification of dynamic positron emission tomography (PET) are discussed, and the quantification of small-animal PET scanners. Some of these relate to characterization and optimization of the scanner and the scanner settings. This is important for dynamic but also static PET acquisitions. Optimized settings can improve the qual- ity of the images, which allows for more accurate quantification. Obtaining a good understand- ing of the possibilities and impossibilities of the scanner, enables investigators to design better study protocols..