Work

Development of a Preclinical PET Scanner With DOI Capabilities Using Semi-Monolithic Detectors

Year: 2025

Type: article

Abstract: Most preclinical PET scanners are based on pixelated detectors without Depth of Interaction (DOI) capabilities, which is crucial to correct for parallax errors. Semi-monolithic crystals have the potential to combine the timing capabilities of pixelated crystals and the 3D positioning accuracy of monolithic scintillators. In this work, we present a preclinical PET prototype consisting of 2 rings defining an inner diameter of 106 mm and an axial length of 52 mm. Each ring contains 14 arrays of 1 × 22 LYSO slabs of 0.97 mm × 25.6 mm × 12 mm, coupled to 8 × 8 SiPMs arrays. The sensitivity, spatial resolution, count rate performance and image quality were studied using the NEMA NU 4-2008 protocol. All images were reconstructed using the MLEM algorithm with 0.5 mm voxel size, including DOI information and normalization correction. A mean spatial resolution for all measured positions and across the three directions (axial, transaxial and radial) of 1.61 ± 0.19 mm was obtained at the center of the FOV. A peak sensitivity of 3.5% was obtained at the center of the scanner, for an energy window (EW) between 358 keV -664 keV. The noise equivalent count rate peak reached 106.9 kcps for an activity of 11.7 MBq using the mouse-sized phantom, the same EW window and a time coincidence window of 10 ns. For the image quality phantom, contrast recovery coefficients of 0.20, 0.62, 0.75, 0.81 and 0.85 were found for the 1, 2, 3, 4 and 5 mm rods, respectively. Spill-over-ratio values of 0.10 for air-filled and 0.23 for water-filled cylinders were measured. Also, according to the Rayleigh criterion, 1.5, 1.2 and 1 mm hot spots of a micro-Derenzo phantom were well distinguished.

Source: IEEE Transactions on Radiation and Plasma Medical Sciences

DOI: 10.1109/trpms.2025.3648052