ISO 15708-3:2025

Overview

ISO 15708-3:2025 - Non-destructive testing - Radiation methods for computed tomography - Part 3: Operation and interpretation - provides practical guidance for operating industrial computed tomography (CT) systems and for interpreting CT results. The standard is targeted at industrial imaging (non‑medical) and covers computed axial tomography only. It defines a consistent set of CT performance parameters and explains how these relate to CT system specifications to help operators select suitable acquisition and reconstruction parameters.

Key topics and technical requirements

• CT system set-up: guidance on geometry, magnification (source–detector distance / source–object distance), detector coverage and how to position the object to maximise spatial resolution while preserving signal‑to‑noise ratio.
• X‑ray source and exposure: selection of tube voltage, current and focal spot to ensure sufficient penetration; recommendation of an attenuation ratio ≤ 1:10 for optimum conditions.
• Acquisition strategy: rotation requirements (at least 180° plus beam angle; typically 360°), projection counts recommendations (ideally ≥ π/2 × matrix size for angular increments and > π × matrix size for best reconstruction), and guidance for region‑of‑interest scans and measurement range extension.
• Reconstruction and visualization: parameter selection for reconstruction algorithms, voxel sizing and visualization techniques to support both defect and dimensional analysis.
• Image quality metrics: definitions and procedures for contrast, noise, signal‑to‑noise ratio (SNR), contrast‑to‑noise ratio (CNR) and spatial resolution (including Annex A on line‑pair gauges).
• Analysis, interpretation and acceptance: steps for feature/defect testing, dimensional testing, acceptance criteria, reporting and record keeping.
• Artefact recognition and mitigation: beam hardening, edge artefacts, scatter, ring artefacts, motion artefacts, centre‑of‑rotation errors, cone‑beam artefacts and instabilities - with advice on how these affect interpretation.

Practical applications and users

ISO 15708-3:2025 is intended for:

• NDT/CT technicians and operators setting up industrial CT scans
• Quality assurance engineers performing non‑destructive inspections
• Metrology teams conducting dimensional analysis of components
• Labs inspecting castings, composites, additive‑manufactured parts, assemblies and welds
• Manufacturers and R&D groups optimizing CT parameters for part qualification and failure analysis

The standard helps users select CT system set‑up, acquisition and reconstruction parameters that balance spatial resolution, contrast and dose for reliable defect detection and dimensional measurement.

Related standards

• ISO 15708-1 - Vocabulary (definitions used across the series)
• ISO 15708-2:2025 - Principle, equipment and samples
• ISO 15708-4:2025 - Qualification

For complete requirements and example procedures, consult the full ISO 15708-3:2025 document available from ISO.