A ROOM TEMPERATURE,LOW NOISE SILICON PHOTODIODE FOR POSITRON EMISSION TOMOGRAPHY

POSITRON EMISSION TOMOGRAPHY (PET) IS A NON-INVASIVE MEDICAL IMAGING TECHNIQUE, WHICH PROVIDES AN IMAGE OF A POSITRON EMITTING RADIO PHARMACEUTICAL AND ITS DISTRIBUTION IN THE BODY ON A METABOLIC LEVEL. AT THE PRESENT TIME, THE PERFORMANCE OF THIS INSTRUMENT IS LIMITED BY THE NUCLEAR SENSORS USED. RESEARCHERS HAVE DEVELOPED A PROMISING DUAL DETECTOR CONCEPT FOR GENERATING HIGH RESOLUTION POSITRON EMISSION TOMOGRAPHS. IN THIS CONCEPT, A PHOTOMULTIPLIER TUBE COUPLED TO SEVERAL SMALL SCINTILLATORS IS THE PRIMARY DETECTOR FOR DETERMINING THE TIME AND THE ENERGY RESOLUTION OF THE INTERACTION, WHILE SMALL PHOTODIODES ATTACHED TO THE OTHER FACE OF EACH SCINTILLATOR IDENTIFY THE CRYSTAL THAT SCINTILLATED. THE DEPTH OF INTERACTION IS DETERMINED BY COMBINING THE SIGNALS FROM BOTH THE PHOTOMULTIPLIER TUBE (PMT) AND THE PHOTODIODE. THE RELATIVELY HIGH NOISE IN CONVENTIONAL P-I-N PHOTODIODES CAUSED BY THEIR LARGE CAPACITANCE IS LIMITING THE PERFORMANCE OF THIS PROMISING PET CONCEPT. THE GOAL OF THE PHASE I PROJECT IS TO DEVELOP NEW TYPES OF LOW CAPACITANCE SILICON PHOTODIODES WHICH CAN OPERATE WITH LOW NOISE AT ROOM TEMPERATURE. IF THE PROJECT IS SUCCESSFUL, THE USE OF THESE NEW PHOTODIODES IN THE DUAL DETECTOR PET CONCEPT PROMISES TO BE THE BREAKTHROUGH NEEDED FOR THE CONSTRUCTION OF NEW GENERATION OF HIGH RESOLUTION PET IMAGING SYSTEMS.