FIG. 6.

Z flying focal spot comparison using (a) no flying focal spots, (b) Phi flying focal spot, (c) Z flying focal spot, and (d) Z and Phi flying focal spot. Large, red arrows highlight windmill artifacts off of a high contrast centering bead, while smaller black arrows highlight their absence in (c) and (d) when the Z flying focal spot is active. Shown with a window/level of 125/−1000 HU. High frequency artifacts (most pronounced in top right image) are due to the ramp filter reconstruction combined with the high, in-plane resolution offered with the Phi flying focal spot; note their disappearance when the Phi and Z flying focal spots are utilized together.