Evaluation of Volumetric Image Quality in X-ray Computed Tomography for Singleand Multi-Material Samples Using Variable Scanning Parameters

X-ray computed tomography (XCT) is increasingly established as an essential tool for quality control, offering the unique capability to gather data from both external surfaces and internal structures of specimens. This study investigates the relationship between XCT scanning parameters and image quality metrics in single-material and multi-material measurements. Using a custom-designed aluminium-polyoxymethylene test artifact with controlled air gaps, we systematically varied parameters including binning configuration, window width, and rotation type to evaluate their effects on signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Results demonstrate that smaller voxel sizes (68 µm) consistently produce higher CNR values and lower measurement errors than larger voxel sizes (149 µm) in single-material scans. In multi-material assemblies, the SNR of air gaps decreases proportionally with increasing gap width (from 25 µm to 125 µm), while measurement errors show distinct patterns depending on binning mode. The gray values of air gaps show distinct separation patterns based on binning, voxel size, and rotation mode. These findings provide valuable insights for optimizing XCT scanning parameters in industrial metrology applications, particularly for multi-material assemblies.