Performance evaluation of the ACTIVE 7 MAX benchtop preclinical PET scanner in accordance with the NEMA NU 4-2008 standard.

INTRODUCTION: ACTIVE 7 MAX is a compact benchtop preclinical PET scanner dedicated to high sensitivity and high-resolution imaging of small animals. This study evaluated the performance of the ACTIVE 7 MAX system using the National Electrical Manufacturers Association NU 4-2008 standard protocol. METHODS: The scanner consists of four rings, each containing 14 detector modules. Each detector module is made up of a 16 × 16 array of lutetium yttrium orthosilicate (LYSO) scintillation crystals, with each crystal measuring 1.47 × 1.47 × 10.0 mm3. The crystal array was coupled to a novel 6 × 6 epitaxial-quenching-resistor silicon photomultiplier (EQR SiPM) array. Flood images and energy resolution were obtained by irradiating each detector module with a 18F source. RESULTS: The average energy resolution for the 56 detector modules in the system was found to be 11.46% in Full Width at Half Maximum (FWHM). The filtered back-projection (FBP) image spatial resolution of a point source varied from 1.57 to 1.81 mm in the radial direction and from 1.58 to 1.71 mm in the tangential direction within the radius of 25 mm. For the Derenzo phantom imaging, the hot rod with a diameter of 1.25 mm was identified. With an energy window of 350-650 keV, the sensitivity at the center of the scanner was 4.18%. The peak noise equivalent count rate (NECR) of 103 kcps was achieved at 22 MBq, and the scatter fraction (SF) is 12%. The reconstructed images of the NEMA image quality phantom show a uniformity of 5.0%, and recovery coefficients for rods with diameters of 1 mm and 5 mm ranging from 0.14 to 0.93. The spillover rates for air-filled and water-filled cold regions were 0.08 and 0.03, respectively. CONCLUSION: This study evaluated the performance of the ACTIVE 7 MAX preclinical PET system. The results demonstrated excellent imaging performance for molecular imaging in biomedical studies.