ISO 15708-3:2017

Overview - ISO 15708-3:2017 (Computed Tomography for NDT)

ISO 15708-3:2017 - "Non-destructive testing - Radiation methods for computed tomography - Part 3: Operation and interpretation" provides operators with clear technical guidance for operating industrial computed tomography (CT) systems and interpreting CT results. It applies to industrial (non‑medical) CT, focuses on computed axial tomography, and gives a consistent set of CT performance parameter definitions and how they relate to system specifications. The standard excludes translational tomography and tomosynthesis.

Key topics and technical requirements

• Operational procedure and CT system set-up
  • Guidance on geometry (source–object–detector distances, magnification) and recommended practices to maximize spatial resolution and signal-to-noise ratio.
  • Optimal cone beam geometry guidance (vertical total cone beam angle typically < 15° for 3D-CT) and rotation requirements (at least 180° plus beam angle; 360° rotation common).
  • Projection acquisition recommendations: ideal number of angular increments ≈ π/2 × matrix size (uneven), and for best reconstruction > π × matrix size.
• X‑ray source and exposure
  • Set voltage and tube current to ensure penetration and small focal spot; aim for an attenuation ratio ≈ 1:10 (sample grey level ≈ 10% of white level). Use pre‑filters to manage beam hardening and intensity.
• Detector setup and corrections
  • Configure exposure time, integrations per projection, digitisation gain/offset, binning; apply offset/gain/bad‑pixel corrections; keep maximum digitised intensity below ~90% saturation.
• Reconstruction, visualization, analysis and interpretation
  • Select reconstruction parameters and visualization settings suitable for feature/defect testing and dimensional metrology.
• Image quality parameters and artefacts
  • Definitions and acceptance criteria for contrast, noise, SNR, CNR, spatial resolution; descriptions and mitigation of artefacts (beam hardening, edge, scatter, rings, motion, centre of rotation errors, cone‑beam distortions).
• Records, reports and suitability criteria
  • Documentation and acceptance criteria to ensure consistent, auditable CT inspection results.

Practical applications and users

ISO 15708-3 is essential for:

• NDT engineers and CT operators performing industrial inspections (castings, composites, assemblies)
• Quality assurance and metrology teams using CT for dimensional measurement and defect detection
• Inspection service providers and contract labs applying standardized CT procedures
• CT equipment manufacturers and software vendors aligning system specs and reconstruction tools with standardized performance definitions
• Researchers or validation teams developing CT inspection procedures and acceptance criteria

Keywords: ISO 15708-3, computed tomography, industrial CT, non‑destructive testing, CT operation, CT interpretation, CT image quality, CT artefacts.

Related standards

• ISO 15708-1:2017 - Terminology for computed tomography (NDT)
• ISO 15708-2:2017 - Principle, equipment and samples (NDT CT)