Positron-Emission-Tomography (PET) scanners play an important role in cancer diagnosis and molecular imaging. Their accuracy overtakes that of the conventional diagnostics systems. They are used, alone or in combination with other imaging systems, such as CT or MRI. The current best detectors for PET are based on LSO crystals that are usually made of 4mm x 4mm x 10mm coupled to PMT, APD, or simila ...