A GSO depth of interaction detector for PET

We have developed a GSO depth of interaction detector. Three GSO scintillators with different concentration of Ce were chosen and stacked along depth of interaction direction and optically coupled to a photomultiplier tube (PMT) or a position sensitive photomultiplier tube (PSPMT). In the beginning, pulse shape, light output and zero-cross time were measured to select a proper combination of GSO scintillators with different concentration of Ce. Selecting three GSO scintillators with different concentration of Ce, a single stacked GSO/PMT depth of interaction detector was fabricated for estimating the possibility of this method. Using the zerocross time analysis, three peaks correspond to decay times of the three GSO scintillators were obtained. Finally, a GSO/PSPMT depth of interaction block detector was fabricated and tested. The block detector consists of 7x7 matrix of GSO scintillators which have three layers of different concentration of Ce optically coupled to a PSPMT. The pulse shape analysis was used for determination of depth of interaction direction while the Anger logic was used for transaxial and axial directions. Good separation was observed in depth of interaction direction as well as transaxial and axial directions. These results indicate that the GSO block detector may become one solution to develop a positron emission tomograph (PET) with depth of interaction detection capability.