NEMA NU‐4 2008 performance evaluation of Xtrim‐PET: A prototype SiPM‐based preclinical scanner

Abstract

Purpose: Xtrim-PET is a newly designed Silicon Photomultipliers (SiPMs)-based prototype PET scanner dedicated for small laboratory animal imaging. We present the performance evaluation of the Xtrim-PET scanner following NEMA NU-4 2008 standards to help optimizing scanning protocols which can be achieved through standard and reliable system performance characterization. Methods: The performance assessment was conducted according to the National Electrical Manufacturers Association (NEMA) NU-4 2008 standards in terms of spatial resolution, sensitivity, counting rate performance, scatter fraction and image quality. The in vivo imaging capability of the scanner is also showcased through scanning a normal mouse injected with 18 F-FDG. Furthermore, the performance characteristics of the developed scanner are compared with commercially available systems and current prototypes. Results: The volumetric spatial resolution at 5 mm radial offset from the central axis of the scanner is 6.81 µl, whereas a peak absolute sensitivity of 2.99% was achieved using a 250-650 keV energy window and a 10 ns timing window. The peak noise-equivalent count rate (NECR) using a mouselike phantom is 113.18 kcps at 0.34 KBq/cc with 12.5% scatter fraction, whereas the NECR peaked at 82.76 kcps for an activity concentration level of 0.048 KBq/cc with a scatter fraction of 25.8% for rat-like phantom. An excellent uniformity (3.8%) was obtained using NEMA image quality phantom. Recovery coefficients of 90%, 86%, 68%, 40% and 12% were calculated for rod diameters of 5, 4, 3, 2 and 1 mm, respectively. Spill-over ratios for air-filled and water-filled chambers were 35% and 25% without applying any correction for attenuation and Compton scattering effects. Conclusion: Our findings revealed that beyond compactness, lightweight, easy installation and good energy resolution, the Xtrim-PET prototype presents a reasonable performance making it suitable for preclinical molecular imaging-based research.

Performance Evaluation and Compatibility Studies of a Compact Preclinical Scanner for Simultaneous PET/MR Imaging at 7 Tesla

“…This can be explained by both instrumentation and electronics improvements. Indeed, the last generation J-Series SiPMs (SensL, Cork, Ireland), offering a high photon detection efficiency [33], was here combined with a FPGA firmware optimized for high count rate acquisitions. All our measurements, including the NECR acquisitions, have been performed by a real-time recording of the coincidence position and the photon energy, instead of a full raw capture board readout transfer to the capture PC acquisition processor.…”

Depth of Interaction Estimation in a Preclinical PET Scanner Equipped with Monolithic Crystals Coupled to SiPMs Using a Deep Neural Network

“…To assess the potential of machine learning in event positioning, two small-animal PET scanners were simulated with two different positioning approaches (conventional Anger login and MLP). For further experimental validation, the number of detector modules and geometrical configuration were similar to the Xtrim preclinical PET scanner recently designed and developed in our lab [14,15].…”

Advances in Preclinical PET Instrumentation

“…Argus(eXplore Vista) 6 1.63 at 5 cm NA 2DFBP ClearPET 6, 21 1.94 at 5 mm 1.9 at 5 mm 12.16 at 5 mm 3DFBP rPET-1 6 1.4 at 5 mm 4 at 5 mm SSRB + FBP VrPET 6, 21 1.48 at center 1.52 at 5 cm 6.54 at 5 mm SSRB + FBP LabPET4 25 1.42 at center NA MLEM + SRM LabPET8 6 1.7 at center 1.65 at 5 mm 7.5 at center SSRB + FBP LabPET12 26 1.65 at 5 mm NA SSRB + FBP X-PET 23 2 at center 12 at center FORE + FBP NanoPET/CT 30 1. 41 1.61 at central coronal plane x 1.54 at central coronal plane y 2.61 anteriorposterior 6.63 at center MLEM PETbox4 42 1.32 at center 3.4 at center 3D MLEM G4 44 w1.35 at center NA MLEM G8 43 <1 at center <1 at 5 mm <1 at center <1 at 5 mm MLEM ClairvivoPET 53 2.16 at 5 cm 13 at 5 mm FORE + FBP TransPET-LH 50 0.95 at center 1 at center 3D OSEM Trans-PET/CT X5 51 2.11 at center 5.72 at center SSRB + FBP Xtrim-PET 55 2.01 at 5 mm 6.81 at center SSRB + FBP IRIS 32 1.05 at 5 mm 1.38 at 5 mm 3DMLEM b-cubes 47 1.06 at center w1 3DFBP VECTor 39 0.6 at center 0.216 at center SR-OSEM (continued on next page)…”

“…This compact and portable design offers w2 mm spatial resolution and 2.99% peak detection efficiency at the CFOV for a 250 to 650 keV energy window. 55 MuPET/CT developed at the University of Texas M.D. Anderson Cancer Center is a low-cost highperformance prototype based on PMT.…”

“…70 Scanners with polygon layout manifest a nonuniform pattern of resolution degradation across the transaxial FOV in contrast to ringlike cylinders owing to dead regions in polygon designs generated by arranging rectangular blocks around an annulus that negatively affects system efficiency and uniformity. 55,66,71 The type of light sensor used to measure the scintillator output is as, if not more, important than scintillation crystals in determining overall scanner's performance. Among the many alternatives available, including PMTs, positionsensitive PMTs (PSPMTs), and multichannel PMTs (MC-PMTs), APDs, and SiPMs; are the default choices in PET devices intended for small-animal imaging.…”