Performance of a PET detector module utilizing an array of silicon photodiodes to identify the crystal of interaction

Initial performance results for a new multilayer positron emission tomography detector module are presented. It consists of an array of 3-mm square by 30-mm deep bismuth germanate (BGO) crystals coupled on one end to a single photomultiplier tube and the opposite end to an array of 3-mm square silicon photodiodes. The photomultiplier tube provides an accurate timing pulse and energy discrimination for all the crystals in the module, while the silicon photodiodes identify the crystal of interaction. When a single BGO crystal at +25°C is excited with 511-keV photons, a photodiode signal centered at 700 electrons (e^-) with noise of 375 e^- full width half maximum (FWHM) is measured. When a four crystal/photodiode module is excited with a collimated line source of 511-keV photons, the crystal of interaction is correctly identified 82% of the time