@misc{oai:repo.qst.go.jp:00069139,
 author = {Nishikido, Fumihiko and Inadama, Naoko and Takahashi, Kei and Shibuya, Kengo and Yoshida, Eiji and Yamaya, Taiga and Lam, ChihFung and Oda, Ichiro and Murayama, Hideo and 錦戸 文彦 and 稲玉 直子 and 高橋 慧 and 澁谷 憲悟 and 吉田 英治 and 山谷 泰賀 and Ｌａｍ ＣｈｉｈＦｕｎｇ and 村山 秀雄},
 month = {Nov},
 note = {Recently, avalanche photodiodes (APDs) are used as photo detector in positron emission tomography (PET) because APDs have many advantages over photomultipliers (PMTs) typically used in PET detector. We are also developing PET detector with a multi pixel APD for small animal PET scanner. In the previous study, we succeed in the identification of four-layer depth of interaction (DOI) with a position sensitive PMT coupled to the backside of a crystal array by only an optimized reflector arrangement. We adopt this method for the APD detector in replacement of the position sensitive PMT. While APDs have many advantages as photo detector, the performance of a detector with APDs is affected by electrical noise because of its low internal gain. Since scintillation lights are shared with many pixels by the presented method, the weaker signal in pixels far from interacting crystals is strongly affected by the noise. To evaluate the possibility of the four-layer DOI detector with APDs by light sharing method, we constructed a prototype DOI detector and tested its performance. We constructed the prototype detector consisting of four layers of a 6 x 6 array with Lu2(1-x)Y2x SiO5 (LYSO) (Lu: 98 %, Y: 2 %) (Proteus Inc., U. S. A.) crystals, and a pixelized APD with a 4x8 pixels array (s8550, Hamamatsu Photonics K.K. ). The size of each crystal element is 1.46 mm x 1.46 mm x 4.5 mm and all surfaces of crystal elements were chemically etched. The experimental result indicates that the four-layer DOI detector with the multi pixel APD can be used as small animal PET detector. In addition, the result of the simulation for the APD detector was identical with experimental data., IEEE 2007 Nuclear Science Symposium and Medical Imaging Conference},
 title = {Four-Layer DOI Detector with a Multi Pixel APD by Light Sharing Method for Small Animal PET.},
 year = {2007}
}