Image quality tests | MAR | No. MAR | |
CT number sensitometry | Air, expected = −1000 HU | −964 HU | −965 HU |
PMP, expected = −200 HU | −182 HU | −183 HU | |
LDPE, expected = −100 HU | −92 HU | −93 HU | |
Polystyrene, expected = −35 HU | −39 HU | −39 HU | |
Acrylic, expected = 120 HU | 118 HU | 119 HU | |
Delrin, expected = 340 HU | 334 HU | 334 HU | |
Teflon, expected = −990 HU | 917 HU | 917 HU | |
Geometric accuracy | Measured distance, expected = 0.5 mm | 0.49 mm | 0.49 mm |
MTF | Critical frequency, 50% (cycles/cm) | 4.01 | 4.02 |
Critical frequency, 10% (cycles/cm) | 6.78 | 6.80 | |
Critical frequency, 5% (cycles/cm) | 7.45 | 7.45 | |
Critical frequency, 2% (cycles/cm) | 8.11 | 8.07 | |
Low contrast | Details at 1% contrast | 5 mm | 4 mm |
Details at 0.5% contrast | 8 mm | 7 mm | |
Details at 0.3% contrast | 9 mm | 9 mm | |
Uniformity | Mean CT value | 7.7 HU | 7.6 HU |
Noise | 15.6 HU | 13.2 HU |