Fabrication and application of a 43 cm x 43 cm carbon-graphite interspaced 2D anti-scatter grid for enhanced cone beam CT

초록

Anti-scatter grids (ASGs) are essential in radiography and fluoroscopy to reduce scattered X-rays, which degrade image quality. Cone-beam computed tomography (CBCT) is particularly susceptible to scatter due to its large field of view and volumetric imaging, whereas conventional one-dimensional (1D)-ASGs offer limited effectiveness against multi-directional scatter. To overcome these limitations, we developed a single-layer two-dimensional (2D)-ASG with carbon-graphite interspaces, fabricated using a sawing method. The ASG was fabricated to cover the entire CBCT flat-panel detector with a large field of view of 43 cm x 43 cm. This require graphite with a density of 1.75-1.95 g/cm3 and porosity below 15% to ensure mechanical stability. The grid septa were composed of a lead-bismuth alloy (Pb:Bi = 48:52) to optimize both structural integrity and scatter rejection. Precision machining and controlled lead filling ensured uniform and defect-free fabrication. Physical characteristics measurements, adhering to the International Electrotechnical Commission 60627 standard demonstrated that the 2D-ASG maintained primary transmission comparable to conventional 1D-ASGs while achieving significantly improved scatter suppression. To assess its practical applicability, the 2D-ASG was integrated into a large field-of-view CBCT system. Imaging tests using animal models demonstrated the feasibility of applying large-area 2D-ASG to CBCT systems, contributing to improved image quality and scatter management for potential use in both research and clinical imaging environments.

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