Design and Simulation of High-Performance PET Scanners Based on Monolithic-like BGO crystals Using GATE Monte Carlo Toolkit.

Background: PET is a highly sensitive imaging modality for visualizing metabolic processes. Objective: This study evaluates PET scanner designs using monolithic-like BGO detector crystals, aimed at enhancing sensitivity while having minimal impact on spatial resolution. Methods: Two PET scanners with 16 detector heads were simulated using the GATE: (1) a total-body (T-B) scanner with a 105cm axial field of view (AFOV), and (2) a whole-body (W-B) scanner with a 35cm AFOV. Both designs employed 1×1×1.6cm³ BGO monolithic-like crystals. The performance of both scanners was assessed according to NEMA NU-2 2018 standards, including sensitivity, scatter fraction, NECR, and spatial resolution, and was compared with existing scanners. Additionally, point source sensitivity at the center of the scanner was compared with an analytical model to validate the simulation results. Results: A good agreement was observed between simulated and analytical point source sensitivities, with a maximum deviation of 4%. The T-B and W-B scanners achieved sensitivities of 39.73 and 17.87 kcps/MBq at the center of the FOV. Scatter fractions were 35.5% and 29.1% for the T-B and W-B scanners, respectively. The NECR peak was 3498.2 kcps at ⁓ 21 kBq/mL for the T-B scanner, and 286.8 kcps at ⁓14 kBq/mL for the W-B scanner. Both scanners demonstrated average spatial resolutions of 2.66mm (T-B) and 2.39mm (W-B) at the center of the scanner. At the center of the FOV, the T-B scanner showed 24% and 41.8% higher sensitivity compared to the Biograph-Vision Quadra and Walk-through PET scanners, respectively. Additionally, the W-B scanner showed 8.3% higher sensitivity at the center compared to the Biograph-Vision. The T-B and W-B scanners achieved 23% and 37.5% better spatial resolution at the scanner center compared to Biograph-Vision Quadra and Biograph-Vision, respectively. Conclusions: The proposed PET scanners with monolithic-like BGO crystals showed promising sensitivity and resolution, indicating improved PET imaging potential.