@misc{oai:repo.qst.go.jp:00071044,
 author = {Yamaya, Taiga and Yoshida, Eiji and Inadama, Naoko and Nishikido, Fumihiko and Tashima, Hideaki and Hirano, Yoshiyuki and Inaniwa, Taku and 山谷 泰賀 and 吉田 英治 and 稲玉 直子 and 錦戸 文彦 and 田島 英朗 and 平野 祥之 and 稲庭 拓},
 month = {Feb},
 note = {1) Introduction
The OpenPET geometry is our original idea to visualize a physically opened space even with a full ring geometry. One of our targets is in-beam PET, which is a method for in situ monitoring of charged particle therapy, as well as PET-IGRT. We have proposed two geometries, a dual-ring OpenPET (DROP) and a single-ring OpenPET (SROP). In this paper, we developed small prototypes, and we evaluated their in-beam imaging performance.
2) Methods
The DROP was our initial idea for the OpenPET, which had a physically opened field-of-view (FOV) between two detector rings separated by a gap. For a dedicated in-beam PET scanner, the DROP was a good candidate, but it was not necessarily the most efficient geometry because it had a wide FOV (i.e., a gap FOV plus two in-ring FOVs) while only a limited FOV around the irradiation field is required in actual use of in-beam PET. Therefore, we proposed the SROP as the second generation OpenPET geometry; the detector ring was the cylinder both ends of which were cut by parallel aslant planes. We developed small prototypes for the DROP and the SROP, which consisted of 16 and 32 depth-of-interaction detectors, respectively. 
3) Results
We carried out in-beam, phantom imaging tests in the HIMAC using a C-11 beam and a C-10 beam as well as a conventional C-12 beam. For both geometries, 3D distribution of primary particles was clearly imaged from only in-beam measurement data for the radioactive beams (C-11 and C-10). For the C-12 beam, a peak generated through auto-activation was visualized with additional off-beam PET measurements.
4) Conclusion
Our initial imaging studies showed promising performance of the OpenPET geometries., Third International Conference on Real-time Tumor-tracking Radiation Therapy with 4D Molecular Imaging Technique},
 title = {OpenPET prototypes for a proof of 3D in-situ imaging of a irradiation field in carbon ion therapy},
 year = {2013}
}