DESIGN OF A DEPTH OF INTERACTION (DOI) PET DETECTOR MODULE

A method to determine depth of interaction (DOI) from a PET detector m odule is described and evaluated. The basic element of the DOI detecto r module is a two crystal detector unit. The hypothesis is that by con trolling how light is shared between two crystals (A and B) DOI inform ation can be extracted from the ratio of light collected using simple Anger type logic [A/(A+B)]. The interface between crystals is designed so that a significant amount of light is shared when a photon interac ts near the front face of a crystal and very little light is shared wh en an interaction occurs near the back of a crystal. The effects of su rface treatment (e.g., polished, roughened) and optical coupling compo unds are investigated. EGO, GSO and LSO detector units have been evalu ated. A DOI uncertainty; of similar to 6mm was attained for the front section (similar to 4mm) of a 2x2x20mm LSO detector unit. A method to decode a 64 crystal detector module (32 detector units) using a 16 cha nnel multi-anode photomultiplier tube is described.