Table 3.

Geometric distortion measured using the Spectronic GRADE phantom, presented as the average of the monthly individual mean and maximum distortions for each given radial distance from the MRI scanner isocenter.

Geometric distortions [mm]
Radial distance from isocenter [mm]	<100	100–150	150–200
Average of mean distortion (1 SD) [range]	0.2 (0.1) [0.1–0.4]	0.3 (0.1) [0.2–0.5]	0.6 (0.1) [0.5–0.8]
Average of max distortion (1 SD) [range]	0.6 (0.1) [0.4–0.8]	0.9 (0.2) [0.6–1.3]	1.8 (0.2) [1.4–2.2]