Performance measurements of a pixelated NaI(Tl) PET scanner

A prototype positron emission tomography (PET) scanner for whole body Aimaging with 4 mm * 4 mm * 30 mm NaI(Tl) crystals and Anger-logic readout has been built and tested. The scanner is composed of 36,540 NaI(Tl) pixels which are coupled to an optically continuous lightguide and a hexagonal closed packed array of 39 mm photomultiplier tubes. The scanner is designed with a crystal-to-crystal diameter of 89 cm and an axial field of view (AFOV) of 25 cm. The main goals of this study are: 1) to overcome the count-rate limitation of the continuous NaI(Tl) scanner (CPET); 2) to improve the spatial resolution and image contrast by using small pixels; and 3) to eliminate the relatively large data gaps between the detectors in the continuous NaI(Tl) scanner. The use of pixelated crystals allows the light spread to be controlled by the proper lightguide design, thereby reducing the spreading of the light relative to a continuous crystal. A two-dimensional position histogram obtained using the pixelated NaI(Tl) scanner shows very good crystal discrimination due to the high light output of NaI(Tl).