Three-dimensional array of scintillation crystals with proper reflector arrangement for a depth of interaction detector

A 16/spl times/16/spl times/4 multicrystal detector module to acquire depth of interaction (DOI) information is proposed for a next generation positron emission tomography scanner that realizes high resolution and high sensitivity. The scintillation crystal array is coupled with a 256ch flat panel position sensitive photomultiplier tube (256ch FP-PMT) having large opening area. One unit consists of 2/spl times/2/spl times/4 crystal elements. The units are arranged in 8/spl times/8 array on a 256ch FP-PMT as a DOI detector module. Its crystal identification performance is evaluated by uniform gamma ray irradiation. The measured scintillation events are mapped on a two-dimensional positioning histogram according to the relative ratio of the multianode output of the FP-PMT. However, peaks corresponding to the crystal elements of one unit form a colony in the resultant positioning histogram and there is large space between adjacent colonies. In order to decrease such useless space, we propose a new method of reflector arrangement for the DOI detector module. Preliminary experiments showed that the more effective position performance was obtained with the proper reflector arrangement in the three-dimensional crystal array. The proposed new method has an advantage in mass production of DOI detector modules.