Revision with unchanged content. Small animal PET scanner is a very powerful tool to study biologic processes in vivo. The performance of the detector module is the central piece for a small animal PET scanner. Discrete crystal detectors have traditionally been used to achieve high spatial resolution for small animal PET scanners. But the cost of fabrication increases considerably as the cross-section of the crystal element gets smaller and smaller. The dead space between the elements also goes up when the number of crystal elements per unit area increases, which equivalently reduce the stopping power of the detector module. This book, therefore, proposed continuous crystal detectors as an. Continuous crystal detectors have the desirable features, such as low cost, simple fabrication, high sensitivity, and potentially high resolution. The analyses help shed some light on an unbiased and efficient position estimator, and depth of interaction decoding techniques. This book should be especially useful for researcher and professionals in small-animal imaging instrumentation field, or anyone else who may be considering utilizing continuous crystal detectors in applications, such as position-sensitive detections.