The application of 3D methodology has recently been receiving increasing attention at many PET centres, and this monograph is an attempt to provide a state-of-the-art review of this methodology, covering 3D reconstruction methods, quantitative procedures, current tomography performance, and clinical and research applications. No such review has been available until now to assist PET researchers in understanding and implementing 3D methodology, and in evaluating the performance of the available imaging technology. In all the chapters, the subject matter is treated in sufficient depth to appeal equally to the physicist or engineer who wishes to establish the methodology, and to PET investigators with experience in 2D PET who wish to familiarize themselves with the concepts and advantages of 3D, and to be made aware of the pitfalls.