Optical Ceramic Hafnates: New Fast PET Scintillator

DESCRIPTION (provided by applicant): We propose to conduct research and development of a new ceramic scintillator based on cerium-activated barium hamate (BaHfO3:-Ce), strontium hafnate (SrHfO3:-Ce), and lutetium hafnate (Lu2Hf2O7:Ce). The development program is prompted by the realization that there is presently only one scintillator that fulfills the needs of PET imaging, namely LSO. While in many ways remarkable, LSO is expensive, it is not widely available and it varies greatly in quality. The hafnates have higher stopping power than LSO, about the same decay time and, being cubic (or nearly cubic), are candidates for fabrication as perfectly transparent optical ceramics. The main advantages of such a development would be much lower cost (ceramic formation is far less expensive than single crystal growth), and possibly improved yield due to much lower fabrication temperatures. The program would take advantage of our extensive experience in ceramic scintillators. The results of Phase I are very encouraging. Ceramic specimens have been fabricated that display light output (under X-ray excitation) comparable to LSO, characteristic decay of 20 - 50 ns, and remarkable translucency. All these properties will be improved by developing the proper procedures to synthesize the precursor powders and optimize the ceramic formation process. This is the essence of the proposed work, which should result in a superior alternative detector for PET.