Object motion effects on the modulation transfer function of a cine CT scanner

The modular transfer function (MTF) of a cine CT scanner for both 50- and 100-msec scan times was determined as a function of object speed and movement direction by imaging a moving bar pattern. MTF measurements were also made with a conventional CT machine. The results were as follows: (1) For a stationary object, the MTF of the 100-msec mode exceeded that of the 50-msec mode. (2) In the 50-msec mode, a difference in spatial resolution was found between the two simultaneously imaged scan levels. (3) For a given object speed, the direction of motion strongly affected the resolution degradation. (4) Fifty-msec scans were degraded only slightly by object motion of less than 5/sec. At this speed, the 100-msec images were degraded, but less than with the conventional scanner