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Table 3 Image quality results for 4:1 and 8:1 sphere-to-background ratio according to the NEMA NU2-2012 standard

From: Performance evaluation of the Biograph mCT Flow PET/CT system according to the NEMA NU2-2012 standard

Sphere diameter (mm) Sphere-to-background ratio = 4:1 Sphere-to-background ratio = 8:1
Contrast recovery (%) Background variability (%) Contrast recovery (%) Background variability (%)
OSEM mean (max/min) PSF + TOF mean (max/min) OSEM mean (max/min) PSF + TOF mean (max/min) OSEM mean (max/min) PSF + TOF mean (max/min) OSEM mean (max/min) PSF + TOF mean (max/min)
10 21.5 (19.1/24.9) 28.5 (24.3/35.4) 5.6 (5.2/5.9) 4.7 (4.0/5.4) 35.3 (33.9/37.7) 42.4 (41.1/45.1) 5.7 (4.9/6.4) 5.5 (5.3/5.6)
13 33.4 (32.7/34.6) 42.3 (41.3/43.9) 4.8 (4.3/5.2) 4.3 (3.7/4.8) 51.5 (49.3/54.1) 63.6 (61.3/65.2) 5.0 (5.6/5.4) 4.8 (4.6/5.0)
17 47.8 (46.2/49.7) 58.4 (56.6/60.1) 3.9 (3.6/4.3) 3.7 (3.4/4.0) 59.6 (58.3/61.3) 68.9 (68.1/69.3) 4.1 (4.0/4.4) 4.1 (3.7/4.3)
22 62.1 (59.7/64.3) 71.7 (67.8/73.6) 3.2 (3.0/3.5) 3.4 (3.2/3.6) 69.9 (68.8/71.2) 76.7 (76.1/77.1) 3.4 (3.4/5.6) 3.4 (3.1/3.7)
28 61.2 (60.4/61.8) 70.1 (69.6/71.0) 2.7 (2.6/3.0) 3.2 (3.1/3.2) 61.8 (59.4/64.4) 70.6 (69.3/71.6) 2.8 (2.6/3.0) 2.9 (2.6/3.1)
37 67.9 (65.7/69.3) 78.3 (76.3/80.2) 2.3 (2.2/2.4) 3.0 (2.9/3.1) 68.2 (68.0/68.6) 78.5 (78.2/78.7) 2.1 (1.9/2.4) 2.5 (2.3/2.6)
Lung residual % (σ) 22.8 (1.6) 12.7 (1.4)    22.3 (1.5) 12.2 (1.2)