@misc{oai:repo.qst.go.jp:00070987,
 author = {Nishikido, Fumihiko and Hirano, Yoshiyuki and Inadama, Naoko and Yoshida, Eiji and Tashima, Hideaki and Satou, Shinji and Inaniwa, Taku and Murayama, Hideo and Ito, Hiroshi and Yamaya, Taiga and 錦戸 文彦 and 平野 祥之 and 稲玉 直子 and 吉田 英治 and 田島 英朗 and 佐藤 眞二 and 稲庭 拓 and 村山 秀雄 and 伊藤 浩 and 山谷 泰賀},
 month = {Nov},
 note = {We are developing the OpenPET which is well suited to in-beam PET in carbon ion therapy thanks to the open space. The in-beam PET can image the distribution of positron emitters during beam irradiation for in-situ dose monitoring. Therefore careful designing and testing of OpenPET detectors are important because secondary particles generated in a target degrade detector performance in the OpenPET geometry and the quantity of positron emitters produced in in-beam PET is very small. In this paper, we optimized the final design of the in-beam OpenPET detector. Some detector components were changed from our previous work for use under practical situations. We carried out in-beam tests of this new detector for carbon beam irradiation with practical intensities. The constructed OpenPET detector consists consisted of a 16x16x4 crystal array with four-layer DOI encoding capability and a PS-PMT. The scintillator material was changed from LGSO that included radio isotopes to GSOZ. In order to compensate for the lower light yield of GSOZ, we applied the PS-PMT (R10552-100-M64) with the super bialkali photocathode which realizes 30% higher quantum efficiency than the conventional bialkali type. A large current divider circuit was applied since the PMT current exceeded the dynamic range of a normal divider circuit under the targeted practical situations. Irradiation tests were done in HIMAC. The energy and intensities of the C-12 beam were 290MeV/u and 10^8 -10^9 particles per second (pps), respectively. The detector was positioned 30cm from the backside of the water phantom at an angle of 30deg. We obtained sufficient crystal identification performance around 10^8 pps, although the position histogram was degrading slightly with increasing C-12 beam intensity. The average energy resolution of 14.9% was obtained for 511keV gamma rays. We concluded that the constructed detector was able to function as the OpenPET detector for in-beam imaging., 2012IEEE NSS&MIC},
 title = {Optimization of the in-Beam OpenPET Detector for Carbon Beam Irradiation},
 year = {2012}
}