The Radiation Detector and Imaging Group with involvement from numerous collaborators has developed pre-clinical radiation imaging systems for small animal research based on positron emission tomography (PET) and single-photon emission computed tomography (SPECT). The group in collaboration with Oak Ridge National Laboratory, Johns Hopkins University and the University of Maryland are developed a SPECT-CT system for imaging unanesthetized, unrestrained mice. The use of anesthesia and physical restraint can change the neurological and physiological processes being studied.