Simultaneous correction of motion and metal artifacts in head CT scanning

摘要

Often patients are found to have metal implants or devices in a head CT scan. The high-density materials create severe artifacts because of beam hardening and scattering effects. Further complication happens when the patient moves at the time of the scan, even if only slightly. The compound artifacts in the reconstructed images are likely to degrade the accuracy of the diagnosis. In this study we propose an approach to correct these compound artifacts based on the knowledge of the measured projections and known xray spectrum. We did this in two steps: 1) in an iterative scheme, rigid motion was estimated and a preliminary reduction of the metal artifacts was performed; (2) the estimated motion was modeled in a full polychromatic reconstruction, in which the starting image was the preliminary corrected image from step 1. The polychromatic reconstruction has the capability to further reduce the compound artifacts. We demonstrate the proposed approach in a simulation study. The image was improved significantly after correction, compared with the one with no correction.