Overview
EN ISO 15708-4:2025 (ISO 15708-4:2025) provides guidance for the qualification of industrial computed tomography (CT) systems used in non-destructive testing (NDT). Published and endorsed by CEN in June 2025, this part of the ISO 15708 series defines CT performance parameters and explains how those parameters relate to CT system specifications. It applies only to industrial (non-medical) CT and excludes other tomography techniques such as translational tomography and tomosynthesis.
Key topics
The standard addresses practical and measurable elements of CT system qualification, including:
- Scope and terminology
- Uses definitions from ISO 15708-1 (vocabulary) for consistent terminology.
- Qualification of testing tasks
- Defect testing: object/feature selection, feature detectability, test system parameterization, verification of suitability and consistency checks, and required documentation.
- Dimensional testing: definition of measurement tasks, system parameterization for dimensional accuracy, degree of accuracy, consistency checks, and documentation.
- Qualification of the CT system
- Integral overall system verification and stepwise checks of components: manipulation system, image scale, beam axis perpendicularity, X‑ray tube focal spot and stability, detector performance, reconstruction algorithms, and visualization.
- Resolution and performance evaluation
- Example methods for CT system resolution evaluation, acquisition parameters, recommendations for reference objects, and density resolution measurement approaches for different energy ranges.
- Documentation
- Requirements for recording qualification results, parameter settings, and evidence of suitability for intended testing tasks.
Practical applications and users
EN ISO 15708-4:2025 is intended for organizations and professionals involved in industrial CT and NDT, including:
- NDT engineers and inspection teams qualifying CT systems for defect detection or dimensional metrology
- Quality assurance managers setting acceptance criteria for CT-based inspections
- CT system manufacturers and integrators documenting compliance and performance claims
- Certification bodies and auditors assessing inspection capability and traceability
Use cases include qualification prior to serial inspections, validation of CT-based dimensional measurement workflows, and routine verification after system changes or maintenance.
Related standards
- ISO 15708-1 - Vocabulary (normative reference)
- ISO 15708-3:2025 - Operation and interpretation (normative reference)
- Other parts of the ISO 15708 series provide complementary guidance on CT techniques, operation, and safety.
EN ISO 15708-4:2025 helps standardize how industrial CT performance is demonstrated and documented, improving repeatability and confidence in CT-based NDT and metrology.