Program Information
Effect of Motion Blur On High Resolution Fluoroscopic (HRF) Detector Projection Views Used for Cone-Beam Computed Tomography (CBCT)
J Krebs*, A Shankar , M Russ , D Bednarek , S Rudin , Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY
Presentations
SU-E-201-4 (Sunday, July 30, 2017) 1:00 PM - 1:55 PM Room: 201
Purpose: Movement of the source and detector can cause image blurring in projection views taken with high resolution detectors for CBCT. A method of accurately predicting image blur was investigated and experimentally verified.
Methods: A high resolution detector with 75um pixels was mounted on an angiographic C-Arm. Lead beads and a metal wire were suspended in the field-of-view (FOV) and imaged as the C-arm rotated. Blurring of a projection view is a function of three variables: rotational speed, distance of the object from isocenter, and frame exposure time. Rotational speed and frame exposure time were kept constant while the vertical position of the suspended objects was changed between consecutive runs. Projection views taken at 0° gantry angle were compared with and without motion for the same table height. The width of the object’s image as measured in the projection was corrected for magnification and plotted showing the linear dependence of blur on distance from isocenter and the dependence of the plot’s slope on rotational speed and frame exposure time.
Results: Comparing projection views with gantry motion to projection views without, showed significant blurring along the direction of motion. Such motion-induced blur would have significant impact on spatial and contrast resolution of projection views used for tomosynthesis or CBCT. A mathematical method for predicting motion blur in a projection view for an object anywhere in the FOV was developed and experimentally verified for the special case in which the object lies along the central axis.
Conclusion: Current CBCT uses pixels of about 400um for which the effect of motion blur would be minor. If detectors with pixels of 75um or less are to be used in CBCT then appropriate methods for reducing the effect of motion blur will be needed when acquisitions are done with continuous gantry motion.
Funding Support, Disclosures, and Conflict of Interest: This research was supported in part by Toshiba Medical Systems Corporation and NIH Grant R01EB002873
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