Geometrical Repeatability and Motion Blur Analysis of a New Multi-projection X-ray Imaging System

We report on the reproducibility and tests for possible motion blur artifacts of a new high frame-rate prototype X-ray multi-projection system recently installed in the Radiology Department of Duke University. The system, which has a translating X-ray tube but a stationary detector, is capable of acquiring oblique-angled full field projection images along both the vertical and horizontal axes at variable speeds and acquisition frame rates. The angular span of the tube movement is +7.5deg to -7.5deg about the posterior-anterior (PA) orientation. To analyze the effect of possible blurring artifact due to motion of the X-ray tube, multi-angled projection images of an edge device were acquired. The modulation transfer function (MTF) determined from the PA projection acquired with and without the tube in motion was compared to investigate blur artifacts that may be introduced due to motion of the X-ray tube. Geometrical precision of the system was assessed at two tube speeds by evaluating the recorded position coordinates as well as edge positions in repeated acquisitions. Excellent geometrical consistency was found in the tube motion. The positional errors at tube speeds of 1 and 2 in/sec were found to be within 1%. The possible effect on the MTF due to motion of the tube was found to be inconsequential. The system was deemed ready for actual clinical trials with these acquisition parameters.