量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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Objectives:
We have proposed the OpenPET, an open type PET, which has a physically opened field-of-view between two detector rings. Especially, the OpenPET has great potential for the real-time tumor-tracking radiation therapy, if real-time imaging is realized. The real-time tumor-tracking is desired especially for the treatment of tumors in mobile organs such as lung moving with respiration. However, the real-time imaging of the PET is challenging task because of its computational burden for the image reconstruction. To the best of our knowledge, no one has ever actually demonstrated the real-time imaging of the PET. Therefore, the aim of this study is to demonstrate the real-time OpenPET imaging by proposing a new system architecture and implementing it on a small prototype system.
Methods:
For real-time image reconstruction, we used recently developed fast PET reconstruction algorithm, 3D one-pass list-mode dynamic row-action maximum likelihood algorithm, and implemented on the GPU. In addition, we proposed a system architecture to stabilize the reconstruction speed by incorporating a data transfer control system which controls data flow and limits maximum data usage in the reconstruction step in every time frame. The proposed architecture was implemented on a single computer connected to the data acquisition system of the small OpenPET prototype.
Results:
Demonstrational experiments of the developed system showed real-time imaging; tracking of a moving point source (1 MBq) was possible in 4D reconstructed images with a frame rate of 2 frames per second.
Conclusions:
The demonstration showed possibility of realizing the PET-guided tumor-tracking radiation therapy. We expect the real-time system also enables PET-guided biopsy. Our next work will include experiments using more complicated and realistic phantoms.
Demonstration of real-time imaging system for the OpenPET toward PET-guided tumor-tracking radiation therapy
