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

Area of Science:

• Medical Imaging
• Radiological Physics
• Computed Tomography (CT)

Background:

• Interior tomography aims to improve CT image quality within a volume-of-interest (VOI) while lowering patient radiation dose.
• Traditional methods using static collimating filters are limited to centered, symmetric VOIs, requiring precise patient positioning and often proving clinically suboptimal.
• Multiple aperture devices (MADs) offer a novel solution, utilizing sequential binary filters for dynamic fluence pattern adjustments.

Purpose of the Study:

• To introduce and evaluate a general approach for VOI imaging using MAD-based fluence field modulation (FFM).
• To demonstrate the capability of MAD-FFM for off-center x-ray beam control.
• To compare image quality and dose metrics of VOI CT with standard full-field CT.

Main Methods:

• Development of a general approach for VOI imaging utilizing MAD-based FFM.
• Physical experiments conducted on a CT test bench.
• Imaging of the spine in an abdominal phantom with off-center x-ray beam control.
• Computation of image quality and dose metrics for both VOI CT and standard full-field CT protocols.

Main Results:

• Successful illustration of off-center x-ray beam control for VOI imaging using MAD-FFM.
• Preservation of image quality within the VOI for VOI CT.
• Significant reduction in integral dose for VOI CT compared to standard full-field CT.

Conclusions:

• MAD-based FFM provides a flexible and effective method for interior tomography.
• VOI CT using MADs can maintain diagnostic image quality while substantially decreasing overall patient radiation exposure.
• This technology holds promise for optimizing CT imaging protocols in various clinical applications.