@misc{oai:repo.qst.go.jp:00064253,
 author = {Yamaya, Taiga and Yoshida, Eiji and Tashima, Hideaki and Kinouchi, Shoko and Suga, Mikio and Nishikido, Fumihiko and Murayama, Hideo and Inaniwa, Taku and Yoshikawa, Kyosan and 山谷 泰賀 and 吉田 英治 and 田島 英朗 and 木内 尚子 and 菅 幹生 and 錦戸 文彦 and 村山 秀雄 and 稲庭 拓 and 吉川 京燦},
 month = {Jun},
 note = {The OpenPET geometry is our original idea to visualize a physically opened space between two detector rings. One of the targets is in-beam PET, which is a method for in situ monitoring of charged particle therapy. The OpenPET is expected to be the first practical 3D geometry, while conventional trials using positron cameras are basically limiting to 2D imaging with low statistics. In the last year, we have developed the small prototype and carried out the initial in-beam tests in the Heavy Ion Medical Accelerator in Chiba (HIMAC). In this paper, we carried out the detailed experiments to show range resolution performance. 
Methods:
The OpenPET prototype (two detector rings of 110 mm diameter separated by a gap of 42 mm) was positioned so that the beam passed through the gap. For usual carbon (12C) beam irradiation, the activity of positron emitters produced through fragmentation reactions is generally low, in addition to the theoretical difference between the dose distribution and positron emitter distribution. Instead of the 12C beam, therefore, we used a 11C radioactive beam as an incident beam directly. A PMMA phantom was placed in the center of the FOV, and irradiated along radial direction by the 11C / 12C pencil beam (~30 Gy).
Results:
For the 11C irradiation, PET images directly corresponding to the distribution of primary particles were obtained with more than ten times higher activity concentration compared with the 12C irradiation. Especially, a 3 mm difference in the range was detectable only from in-beam measurement data, while additional off-beam measurement was required for the 12C beam.
Conclusion:
We showed feasibility of PET image-guided carbon ion therapy. Our next work will include exploration of performance limitation for the reduced irradiation dose., ISNM 2011 Annual Meeting},
 title = {In-beam imaging performance of the small OpenPET prototype for carbon ion therapy},
 year = {2011}
}