Design of a depth of interaction detector with a PS-PMT for PET

A detector unit using a depth encoding scheme was designed and evaluated. The detector unit consists of four crystal blocks in a 2/spl times/2 array coupled to a position-sensitive photomultiplier tube (PS-PMT) having metal channel dynodes and 4/spl times/4 multianodes. Each crystal block consists of three stages of 2/spl times/2 GSO arrays of which element size is 3.8 mm/spl times/3.8 mm/spl times/10 mm. Each scintillation event is mapped on a two dimensional positioning histogram according to the relative ratio of the output signals of the PS-PMT. With appropriate light control in the crystal block, good positioning performance for Cs-137 photons was obtained.