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In order to detect the breast cancer at the early stage with high efficiency, we intend to develop positron emission mammography (PEM), using Pr:LuAG single crystal as a scintillator of this scanner. PEM has the same mechanism of PET, where two 511 keV annihilation gamma-rays are detected by two gamma cameras at opposite side, and reconstruction of the data shows the position of the cancer with malignancy grades. After cutting and polishing processes for each crystal to a physical dimensions of 2.1 x 2.1 x 15 mm³, Pr:LuAG array covered with BaSO4 reflector was used as a sensor head. The one camera unit consisted of 20 x 64 pixels optically coupled with three H8500-03 multi anode PMTs. Our PEM required four cameras at each side. Finally, eight cameras were installed in both sides of the prototype instrument and the spatial resolution was evaluated using the 18F in the breast phantom. [ABSTRACT FROM AUTHOR]

Ce2% : 6LiCaAlF6 (6LiCAF) single crystal (nominal composition) with 2 mm in diameter and 50 mm in length was grown by the micro-pulling-down method. Emission from the perturbed Ce3+ centers was observed in an α-ray excited radioluminescence. The neutron response was compared with Li-glass (GS20, Saint-Gobain) using 252Cf. The scintillation decay time of Ce2% 6LiCAF is 38 nsec, which is twice as short as that of GS20. Using Hamamatsu photomultiplier H7416 the photoelectron yield about a half of that of GS20 has been measured for the Ce : 6LiCAF single crystal. Considering the light yield of GS20 (6000 phot/neutron) and the spectral correction due to the different emission peak position in both materials, the light yield of Ce : 6LiCAF single crystal is estimated about 4200 phot/neutron. [ABSTRACT FROM AUTHOR]

Ce2% : 6LiCaAlF6 (6LiCAF) single crystal (nominal composition) with 2 mm in diameter and 50 mm in length was grown by the micro-pulling-down method. Emission from the perturbed Ce3+ centers was observed in an α-ray excited radioluminescence. The neutron response was compared with Li-glass (GS20, Saint-Gobain) using 252Cf. The scintillation decay time of Ce2% 6LiCAF is 38 nsec, which is twice as short as that of GS20. Using Hamamatsu photomultiplier H7416 the photoelectron yield about a half of that of GS20 has been measured for the Ce : 6LiCAF single crystal. Considering the light yield of GS20 (6000 phot/neutron) and the spectral correction due to the different emission peak position in both materials, the light yield of Ce : 6LiCAF single crystal is estimated about 4200 phot/neutron. [ABSTRACT FROM AUTHOR]