Scintillation crystals coupled to photomultiplier tubes or silicon diodes are the most common detectors for X-ray/3-ray detection. Imaging modalities such as positron emission tomography (PET), single photon emission computed tomography (SPECT), digital radiography (including digital mammography) and X-ray CT are critically important for cancer diagnosis, staging, treatment tracking and research. High resolution and high efficiency detectors used in imaging modalities such as PET widely use high density, high refractive index scintillators such as cerium-doped lutetium oxyorthosilicate (LSO: Ce). When such high refractive index scintillators are coupled to detectors such as photomultiplier tubes (PMT) or avalanche photodiodes (APD), the mismatch in the refractive index of the scintillator and the detector cause only a small fraction of the light generated within the scintillator to exit the surface of the scintillator, and thereby be sensed by the photodetector. The use of a coupling fluid or gel between the scintillator and the detector helps only marginally. The proposed research will use recent advancements in nanofabrication techniques for creating photonic band gap structures to enhance the light extraction efficiency of scintillators, thereby improving the time and energy resolutions of PET detectors.
PROJECT NARRATIVE Scintillation crystals coupled to photomultiplier tubes or silicon diodes are the most common detectors for X-ray/3-ray detection. High density, high refractive index scintillators currently used in positron emission tomography (PET) detectors are often plagued by an inefficient extraction of the scintillation light that results in inaccuracy (often significant) in event coincidence timing sufficient to affect spatial resolution. The goal of the proposed research is to demonstrate the feasibility of using novel photonic band gap structures to improve timing and spatial resolution in PET detectors by the efficient extraction of scintillation light from such high density, high refractive index scintillators.
