Investigation of a whole-body DOI-PET system

In this study, we were conducting basic research on a whole-body depth of gamma-ray interaction (DOI) positron emission tomography system which provides spatial resolution that is both high and uniform, and also minimizes costs. The detectors consist of double-layer 9×10 GSO/GSO phoswich crystal blocks, a light guide and two rectangular PMTs. Individual crystal sizes are 2.45×5.1×15 mm3, and each layer of crystal blocks has a different decay time. Many of the circuit boards used in our current conventional PET system (SET-3000G SHIMADZU Japan) have been optimized for DOI acquisition. The detectors are arranged to form a 332.5 mm radius detection ring, and spatial resolution is obtained from the center to the edge of the 250 mm radius field of view. The effect of DOI was confirmed using a comparison with the non-DOI systems.