A Promising Future: Comparable Imaging Capability of MRI-Compatible Silicon Photomultiplier and Conventional Photosensor Preclinical PET Systems

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FIGURE 1.
(A) Overlap positions for lutetium-yttrium oxyorthosilicate scintillation crystal (red) and SiPM sensor (green) in MiniPET-3 detector module. (B and C) Energy resolution maps of MiniPET-2 (B) and MiniPET-3 (C).
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FIGURE 2.
Position maps (A and B) and line profiles (C and D) of MiniPET-2 (A and C) and MiniPET-3 (B and D).
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FIGURE 3.
Dependence of coincidence timing window on random, true, and NEC-like [true²/(true + 2 × random)] counting rates for MiniPET-3.
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FIGURE 4.
Dependence of FWHM on radial distance at one-quarter offset from axial center for MiniPET-2 (A) and MiniPET-3 (B).
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FIGURE 5.
(A and B) Reconstructed images of NEMA NU 4 image-quality phantom for MiniPET-2 (A) and MiniPET-3 (B). (C) Corresponding recovery coefficient dependence on rod radius for both systems.
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FIGURE 6.
NEC performance measured with NEMA NU 4 rat phantom for MiniPET-2 and MiniPET-3.

TABLE 1

Physical and Technical Parameters of MiniPET-2 and MiniPET-3

Parameter	MiniPET-2	MiniPET-3
Detector module
Scintillator material	Lutetium-yttrium oxyorthosilicate	Lutetium-yttrium oxyorthosilicate
Crystal size (mm³)	1.27 × 1.27 × 12	1.27 × 1.27 × 12
Crystal pitch (mm)	1.347	1.347
Crystal array size	35 × 35	35 × 35
Photon sensor	PMT; Hamamatsu	SiPM; ST Microelectronics
System
Number of detector modules	12	12
Number of detector rings	35	35
Inner diameter of detector ring (mm)	211	211
Solid angle/4π	0.22	0.22
Axial field of view (mm)	48	48
Transaxial field of view (mm)	100	100

TABLE 2

Sensitivity and Spatial Resolution Parameters of MiniPET-2 and MiniPET-3

Parameter	MiniPET-2	MiniPET-3
Energy window (keV)	350–650	360–662
τ-value (ns)	6.0	8.0
Spatial resolution at one-quarter offset from axial center
Tangential (mm)	1.36	1.24
Radial (mm)	1.57	1.15
Axial (mm)	1.83	1.23
Sensitivity
Peak absolute sensitivity (%)	1.37	1.36
Total absolute sensitivity (%)	0.6	0.7
Image quality
Uniformity (%SD)	5.59	6.49
Spillover ratio for air	0.15	0.14
Spillover ratio for water	0.26	0.24
Counting rate performance
NEC peak (rat phantom)	14 kcps (at 36 MBq)	24 kcps (at 43 MBq)
NEC peak (mouse phantom)	55 kcps (39 MBq)	91 kcps (at 44 MBq)
Scatter fraction (rat phantom)	17.4%	16.1%
Scatter fraction (mouse phantom)	5.6%	4.8%