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