@article{oai:repo.qst.go.jp:00046664,
 author = {Yoshida, Eiji and Hirano, Yoshiyuki and Tashima, Hideaki and Inadama, Naoko and Nishikido, Fumihiko and Moriya, Takahiro and Omura, Tomohide and Watanabe, Mitsuo and Murayama, Hideo and Yamaya, Taiga and 吉田 英治 and 平野 祥之 and 田島 英朗 and 稲玉 直子 and 錦戸 文彦 and 大村 知秀 and 村山 秀雄 and 山谷 泰賀},
 issue = {5},
 journal = {IEEE Transactions on Nuclear Science},
 month = {Oct},
 note = {The X'tal cube is our original PET detector, which is being developed to achieve isotropic 3D positioning detectability. The X'tal cube is based on a 3D segmented crystal block for which all surfaces are covered with photo-detectors. Previously, instead of our initial approach of gluing segmented pieces of crystals, we successfully constructed a crystal block segmented by laser processing, and we developed the X'tal cube with the laser-processed 3D square grids of 2 mm length. In this paper, we extend the laser processing to 3D square grids of 1 mm length. The volume of a 1-mm crystal segment is 1/8 of that of a 2-mm crystal segment.We
also evaluate imaging resolution performance with a newly developed one-pair prototype system to simulate a ring-type scanner, while our previous reports were limited to development and evaluation of a single detector. In particular, we compare 1-mm X'tal cube detectors to 2-mm X'tal cube detectors. The one-pair prototype system consisted of two X'tal cubes, two rotating stages, and a
192-channel data acquisition system. Each X'tal cube consisted of the LYSO cubic crystal block of 18 18 18mm in which the 3D grids of 1 mm pitch were fabricated by internal laser processing. The 4 4 arrays of multi pixel photon counters were optically coupled to each surface of the crystal block. The detector positions
were automatically controlled to simulate a ring-type PET with a 14.6 cm diameter. Data were collected for all assumed detector positions and then a sinogram was obtained. The data were reconstructed using filtered backprojection. The average spatial resolution of the 2-mm X'tal cubewas 1.9mmfullwidth at half maximum (FWHM) over the field-of-view (FOV). On the other hand, the average spatial resolution of the 1-mm X'tal cubewas 1.3mmFWHM over the FOV. By applying deconvolution with the assumption that the point source was a Gaussian function of 1.0mmFWHM, we estimated
the average spatial resolution of the 2-mm X'tal cube and the 1-mm X'tal cube as 1.6 mm FWHM and 0.83 mm FWHM, respectively. The average spatial resolution of the 1-mm X'tal cube was improved approximately 48% compared to the 2-mm X'tal cube. In conclusion, we confirmed the potential of the X'tal cube for uniform and high resolution imaging.},
 pages = {3172--3180},
 title = {Impact of Laser-Processed X'tal Cube Detectors on PET Imaging in a One-Pair Prototype System},
 volume = {60},
 year = {2013}
}