講演情報
[10p-E204-4]GATE Monte Carlo simulation of SSLE-PET for sub-second dynamic mouse imaging
〇HanGyu Kang1, Hideaki Tashima1, Toshiaki Sakai2, Taiga Yamaya1 (1.QST, 2.Hamamatsu Photonics)
キーワード：
PET、Depth-of-interaction、Monte Carlo simulation
Last year, we reported on an ultrasensitive preclinical positron emission tomography (PET) scanner with 4-layer depth-of-interaction (DOI) detectors, thereby allowing sub-second dynamic imaging of a rat. However, the crystal pitch and DOI bins were 2.8 mm and 7.5 mm, which were not suitable for mouse imaging. On the other hand, fabrication of finely pixelated crystal arrays remains technically challenging. Here, we designed a novel preclinical PET scanner that uses a sub-surface laser engraving (SSLE) technique to fabricate the finely pixelized crystal elements, and we call it the SSLE-PET (Fig. 1). The SSLE-PET comprises 12 DOI detectors, each of which has 20 mm long tapered LYSO crystals. Each monolithic LYSO crystal was optically segmented by SSLE, providing fine crystal pitches (top=1.0 mm, bottom=1.6 mm) and 2.5 mm DOI bins. We employed GATE simulation to investigate the effects of inner diameter (i.e. detector gap) imaging performance of the SSLE-PET. For imaging performance evaluation, a resolution phantom having different rod diameters (0.75, 1.0, 1.35, 1.7, 2.0, and 2.4 mm) was used. The GATE output file was reconstructed by using a filtered back projection algorithm with an energy window of 400-600 keV. The gap artifacts appeared when the inner diameter increased from 60 mm to 70 mm (Fig. 2). Hence, an inner diameter of 65 mm would be the best choice to avoid any mechanical collision between detectors, while maintaining the image quality. The peak sensitivity of 21.4% was achieved with an axial coverage of 88 mm. Even with a 0.5 s scan frame, the 1.35 mm rod structures were well identified (Fig. 3). As a next study, we plan to develop a prototype SSLE-PET scanner based on the GATE simulation results.