Molecular imaging techniques enable the visualization of biological processes in living organisms. These techniques rely on synthetic biomolecules (‘tracers’) that specifically target a physiological process of interest without significantly disturbing it, and that poses some property which allows them to be detected externally. If the detectable property is radioactivity, the molecules are referred to as radiotracers, and the imaging technique is referred to as nuclear imaging. The aims of the research presented in this work are to determine the spatial resolution experimentally, the energy resolution and time resolution attainable with monolithic scintillator detectors, to analyze the dependence of these detector properties on physical quantities such as the scintillator light yield, the APD gain and the noise characteristics of the frontend electronics, and to predict the performance of a small animal PET system based on these detectors. The research presented in this publication is primarily based on experimental work on prototype detector modules. Simulation studies have been carried out in parallel; these are presented elsewhere. Some of the results of these simulation studies are also used in this work.