PET and SPECT imaging has improved to such a level that they are opening up exciting new horizons in medical diagnosis and treatment. This book provides a complete introduction to fundamentals and the latest progress in the field, including an overview of new scintillator materials and innovations in photodetector development, as well as the latest system designs and image reconstruction algorithms. It begins with basics of PET and SPECT physics, followed by technology advances and computing methods, quantitative techniques, multimodality imaging, instrumentation, pre-clinical and clinical imaging applications.