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内容記述 |
Spatial resolution is the most important factor for preclinical positron emission tomography (PET) especially for rodent brain imaging. Previously, we developed a mouse brain PET scanner with staggered 3-layer DOI detectors using 0.8 mm crystal pitch thereby achieving 0.45 mm resolution. However, there is still room for spatial resolution improvement with finer crystal pitch. Here we propose a new mouse brain PET design to further enhance in spatial resolution. The proposed PET scanner consists of staggered 3-layer DOI detectors using 0.6 mm crystal pitch. The crystal thicknesses of the 1st, 2nd, and 3rd layers are 3, 3 and 5 mm thereby resulting in a total thickness of 11 mm. The PET has a 48 mm ring diameter and 22.6 mm axial FOV with 2-ring structure. Each ring has 16 DOI detectors. We conducted GATE Monte Carlo simulations to investigate the achievable spatial resolution with the proposed PET. To evaluate the spatial resolution, four NEMA 22Na sources (D=0.25 mm) with spacing of 5 mm in the radial direction were scanned with an energy window of 400-600 keV and reconstructed using FBP algorithm. To evaluate imaging performance, a resolution phantom having six different rod diameters (0.45, 0.50, 0.55, 0.6, 0.7, and 0.8 mm) was scanned and reconstructed by using OSEM algorithm with 8 subsets and 50 iterations. The average spatial resolution with FBP algorithm was 0.55±0.07 mm, which was 22% better than that of the previous work in JSAP2024. The 0.45 mm rods of the resolution phantom could be resolved with a valley-to-peak ratio of 0.440±0.104, which is under the Rayleigh criterion (0.735). In the near future, we plan to develop a prototype mouse brain PET scanner to validate the GATE simulation results. |
