@article{oai:repo.qst.go.jp:00046920,
 author = {Nishikido, Fumihiko and Inadama, Naoko and Yoshida, Eiji and Murayama, Hideo and Yamaya, Taiga and 錦戸 文彦 and 稲玉 直子 and 吉田 英治 and 村山 秀雄 and 山谷 泰賀},
 journal = {Nuclear Instruments & Methods in Physics Research Section A},
 month = {Oct},
 note = {Silicon photomultipliers (SiPMs) provide many advantages for PET detectors, such as their high internal gain, high photon detection efficiency and insensitivity to magnetic fields. The number of detectable scintillation photons of SiPMs, however, is limited by the number of microcells. Therefore, pulse height of PET detectors using SiPMs is saturated when large numbers of scintillation photons enter the SiPM pixels. On the other hand, we previously presented a depth-of-interaction (DOI) encoding method that is based on the light sharing method. Since our encoding method detects scintillation photons with multiple readout pixels, the saturation effect can be suppressed. We constructed two prototype four-layer DOI detectors using a SiPM array and evaluated their performances.
 The two prototype detectors consisted of four layers of a 6   6 array of Lu 2(1 x) Y 2x SiO 5 (LYSO) crystals and a SiPM (multi-pixel photon detector, MPPC, Hamamatsu Photonics K.K.) array of 4   4 pixels. The size of each LYSO crystal element was 1.46 mm x 1.46 mm x 4.5 mm and all surfaces of the crystal elements were chemically etched. We used two types of MPPCs. The first one had 3600 microcells and high photon detection efficiency (PDE). The other one had 14,400 microcells and lower PDE. In the evaluation experiment, all the crystals of the detector using the MPPC which had the high PDE were clearly identified. The respective energy and timing resolutions of lower than 15% and 1.0 ns were achieved for each crystal element. No saturation of output signals was observed in the 511 keV energy region due to suppression of the saturation effect by detecting scintillation photons with several MPPC pixels by the light sharing method.},
 pages = {755--761},
 title = {Four-layer DOI PET detectors using a multi-pixel photon counter array and the light sharing method},
 volume = {729},
 year = {2013}
}