@misc{oai:repo.qst.go.jp:00065280,
 author = {Tashima, Hideaki and Yoshida, Eiji and Shinaji, Tetsuya and Haneishi, Hideaki and Yamaya, Taiga and et.al and 田島 英朗 and 吉田 英治 and 品地 哲弥 and 羽石 秀昭 and 山谷 泰賀},
 month = {Nov},
 note = {We are developing the OpenPET, which can provide an open space observable and accessible to the patient during positron emission tomography (PET) measurement. The OpenPET enables integration of treatment and diagnosis. The most attractive and realistic candidate application is in combination with radiation therapy. OpenPET imaging during particle therapy such as carbon beam treatment has the potential to visualize the irradiation field of a patient. In addition, as a more challenging application, we are focusing on tumor tracking by means of PET, which is conventionally done by marker implantation and X-ray imaging. 
In this study, we proposed a real-time imaging system for the OpenPET as we work toward implementing the PET-guided tumor tracking radiation therapy and we demonstrated its tracking ability using a point source and a small OpenPET prototype. The system employed 3D dynamic row-action maximum likelihood algorithm (DRAMA) and implemented on graphical processing unit (GPU). The point source was moved according to the sine curve with a cycle of 30 s. The frame rate of the real-time imaging system was 2.0 frames per second. As a result of sine curve fitting, the average delay was 2.1 s.
 In addition, we conducted Monte Carlo simulation to assess conditions under which the tumor tracking is feasible using 18F-FDG in a human body scale. We assumed that the OpenPET measurement was started 100 minutes after the 18F-FDG injection of 370 MBq. The time window was 0.5 s. As a result, we showed that the tumor tracking is feasible if the tumor contains sufficient radioactivity in the case of lung cancer. 
Although we have demonstrated real-time tumor tracking using a small OpenPET prototype, further improvement is necessary for applying to the human-sized OpenPET. Therefore, we are developing faster image reconstruction system using a multi-GPU platform and region-of-interest reconstruction technique to minimize image matrix size keeping spatial resolution.  In addition, we are developing a time delay correction method using the signal from an additional external device., PIPA},
 title = {Real-time OpenPET imaging system toward PET-guided tumor tracking radiation therapy},
 year = {2013}
}