[18a-D62-1~6] 2.4 医用応用

11:00 〜 11:15英語発表

[18a-D62-5] Design of a sub-0.5 mm resolution mouse brain PET

〇(P)HanGyu Kang¹, Hideaki Tashima¹, Taiga Yamaya¹ (1.QST)

キーワード：

Positron emission tomography、Monte Carlo simulations、High resolution

Spatial resolution is the most important factor for mouse brain dedicated positron emission tomography (PET). Previously, we obtained 0.55 mm resolution with small animal PET, however our original goal of sub-0.5 mm resolution was not realized because of the unoptimized crystal layer design. Here we proposed a mouse brain PET design with an optimized crystal layer design that can achieve sub-0.5 mm resolution. The newly proposed mouse brain PET design consists of a staggered 3-layer DOI detector using 0.8 mm crystal pitch. The geometry has a 48 mm ring diameter and 23.4 mm axial FOV. The PET has 2 rings each of which has 16 DOI detectors. We conducted GATE simulations to optimize the crystal layer design which can provide the best spatial resolution throughout the field-of-view. Three different crystal layer designs were used: (A) 4+4+7 mm, (B) 3+4+4 mm, and (C) 3+3+5 mm. To evaluate the spatial resolution, four NEMA ²²Na sources (D=0.25 mm) with spacing of 5 mm in the radial direction were used. With the optimized crystal layer design, we evaluated the imaging performance with a resolution phantom having six different rod diameters (0.45, 0.50, 0.55, 0.6, 0.7, and 0.8 mm). The PET images were reconstructed by using an OSEM algorithm. An energy window of 440-560 keV was used for the image reconstruction. Design (C) (3+3+5 mm) showed the best spatial resolution (0.42 mm at the center and 0.46 mm at the 5 mm radial offset) among the three. The 0.45 mm rods of the resolution phantom could be resolved with a valley-to-peak ratio of 0.573±0.062, which is under the Rayleigh criterion (0.735). In conclusion, our proposed mouse brain PET with the optimized crystal layer design provided sub-0.5 mm resolution. In the future, we plan to develop a prototype mouse brain PET scanner to validate the simulation results.