Scatter Reduction and Correction for Dual-Source Cone-Beam CT Using Prepatient Grids

Area of Science:

• Medical Imaging
• Radiological Physics

Background:

• Scatter significantly degrades image quality in dual-source cone-beam CT (DS-CBCT), causing artifacts and reducing key metrics like contrast-to-noise ratio (CNR) and Hounsfield unit (HU) accuracy.
• Previous interleaved acquisition modes reduced cross-scatter but increased scan time and did not address forward scatter.

Purpose of the Study:

• To develop and evaluate a prepatient grid system for DS-CBCT to mitigate both forward and cross-scatter.
• To improve image quality metrics including CNR, HU accuracy, and uniformity.

Main Methods:

• A prepatient grid system was implemented on both X-ray sources for physical scatter reduction during acquisition.
• Scatter was measured in blocked regions for post-scan correction, and complementary projections were merged.
• Experiments utilized various phantom sizes, grid blocking ratios, acquisition modes, and reconstruction algorithms.

Main Results:

• The prepatient grid system effectively reduced scatter artifacts and improved CNR, HU accuracy, and uniformity.
• Simultaneous acquisition mode with scatter correction achieved CNR comparable to interleaved and sequential modes.
• Iterative reconstruction with total variation regularization outperformed FDK in reducing scatter correction-induced noise.

Conclusions:

• The prepatient grid system is effective in removing scatter effects in DS-CBCT, particularly in simultaneous acquisition mode.
• This system enables scanning time reduction and facilitates dual-energy imaging applications.
• The developed system enhances the diagnostic utility of DS-CBCT by improving image quality.