Spectral CT using a fine grid structure and varying x-ray incidence angle

Area of Science:

• Medical Imaging
• Physics
• Materials Science

Background:

• Spectral computed tomography (CT) is increasingly used for diagnostics and therapy evaluation.
• Distinct spectral sensitivities allow for material discrimination, quantitative density estimation, and artifact reduction.

Purpose of the Study:

• Introduce a novel spectral CT concept utilizing a fine-pitch grid for X-ray beam prefiltration.
• Demonstrate the ability to perform spectral CT acquisitions and material decomposition.

Main Methods:

• Developed physical models and illustrated operating principles of grid-based spectral shaping.
• Fabricated a prototype tungsten lamellae grid and compared spectral shaping via simulations and physical measurements.
• Integrated the grid onto a CT test bench and scanned an iodinated phantom.

Main Results:

• X-ray spectrometer measurements confirmed controllable spectral shaping with small angle changes, aligning with simulations.
• Identified critical angles for dramatic spectral characteristic changes.
• Reconstructed projection data and performed material decomposition into iodine and water, showing good agreement with known concentrations.

Conclusions:

• The grid-based approach is feasible for spectral CT data acquisition and accurate material decomposition.
• This novel concept could serve as a simple upgrade for standard energy-integrating CT systems.