SUMMARY Positron emission tomography (PET) is unrivaled as a highly specific and sensitive means for tomographic imaging of molecular interactions and pathways in humans, offering great utility for translational medicine. Recently, long axial field-of-view PET scanners, which provide excellent geometric coverage, giving much better detection sensitivity, have been developed. However, cost and performance issues are raised as concerns. To resolve both cost and performance issues, next generation long axial field-of-view PET detector modules should employ new scintillators to realize the full performance capabilities of PET at a viable price point. A proposed ceramic scintillator has extremely high stopping power and density, better than any currently used scintillator for PET. The proposed scintillator has a high light yield and an excellent energy resolution. Moreover, we achieved a very good coincidence timing resolution. In addition, it has a cubic crystal structure allowing fabrication by ceramic processing, with potential for a major reduction in cost compared with L(Y)SO. This proposal is 1) to develop the new ceramic scintillator for PET with large volumes and high clarity, 2) to characterize the new scintillator as a PET scintillator, 3) to apply the new scintillator array blocks into well- designed existing PET detector modules to evaluate performance of the new scintillator at the module level, and finally 4) to develop novel time-of-flight (TOF)-PET detector modules by combining the new ceramic scintillator and advanced PET readout methods for next-generation PET scanners. The proposed ceramic scintillator and PET detector modules are not limited to long axial field-of-view PET scanners and will be widely usable. The impact of this proposal is that it provides a pathway to 1) realizing long axial field-of-view scanners with unprecedented sensitivity without a proportional increase in scanner cost and 2) enabling performance advantages in shorter scintillators in terms of reducing DOI effect and improving timing and energy resolution without losing detection efficiency for next-generation TOF-PET scanners.

NARRATIVE Positron emission tomography (PET) is a highly specific and sensitive imaging technique that visualizes molecular interactions, having a significant impact on biomedical research and translational medicine. This proposal develops high-performance and cost-effective time-of-flight PET detector modules based on the ultra- dense and fast ceramic scintillator. The proposed research will lead to next-generation PET scanners with superior performance and lower cost.