What is a Voxel?
A voxel is the smallest volume element of a reconstructed CT dataset. The topic is a methodological foundation for reliable CT data, because it directly affects detection limits, measurement capability and reproducibility.
Scientific background
The scientific basis is rooted in the physical interaction of X-ray radiation with matter and in the mathematical data processing of projections. Relevant concepts include the mapping between detector pixels, geometric magnification and the isotropic volume grid. For technical decisions, these relationships must be understood as a quantifiable measurement chain.
Relevant key metrics
- Spatial resolution, contrast-to-noise ratio and measurement uncertainty are the central parameters.
- Systematic effects are controlled via calibration, reference standards and repeat measurements.
- Parameter changes must be evaluated for robustness and transferability to series production conditions.
Standards and thresholds
- Standards: ISO 15708-1:2024 and ISO 15708-2:2025 (terminology and CT principles).
- Typical thresholds (in practice): Smallest evaluable structure typically at least 2-3 voxels; for robust defect evaluation usually at least 3 voxels.
- Validity: Voxel size alone does not determine measurement quality; the entire measurement chain, including noise and artifacts, is decisive.
Application in industrial practice
- Design of valid scan parameters for defect and measurement tasks.
- Objective interpretation of CT findings in development and series production.
- Comparability of results across systems, batches and time points.
Sources and reference date
- ISO 15708-1:2024.
- ISO 15708-2:2025.
- Reference date: February 2026.