Volume-of-interest CT imaging with dynamic beam filtering using multiple aperture devices.

Interior tomography is promising approach for retaining high quality CT images within a volume-of-interest (VOI) while reducing the total patient dose. A static collimating filter can only image a centered symmetric VOI, which requires careful patient positioning and may be suboptimal for many clinical applications. Multiple aperture devices (MADs) are an emerging technology based on sequential binary filters that can provide a wide range of fluence patterns that may be adjusted dynamically with relatively small motions. In this work, we introduce a general approach for VOI imaging using MAD-based fluence field modulation (FFM). Physical experiments using a CT test bench are conducted illustrating off-center x-ray beam control for imaging the spine in an abdominal phantom. Image quality and dose metrics are computed for both standard full-field CT and VOI CT. We find that the image quality within the VOI can be preserved for VOI CT with a significant drop in integral dose as compared with a standard full-field protocol.