ISO 15708-1:2017

Overview

ISO 15708-1:2017 - "Non-destructive testing - Radiation methods for computed tomography - Part 1: Terminology" defines the standardized vocabulary for computed tomography (CT) within non-destructive testing (NDT). The document collects CT-specific and more general imaging and radiography terms, clarifies meanings (with some discussion points) and frames terminology to the specific context of CT. It is a reference for consistent language in documentation, testing procedures, specifications and training.

Key Topics

The standard focuses on precise definitions and concepts used in CT and radiographic imaging, including:

• Basic interaction mechanisms: absorption (photoelectric effect) and Compton scattering as photon–matter interactions.
• Beam characteristics: beam hardening (spectral change) and related effects such as the cupping effect.
• Acquisition geometries: cone‑beam, fan‑beam, and parallel‑beam CT modes.
• Data and image elements: projection, sinogram, reconstruction, image (tomogram), slice, volume, pixel and voxel.
• Quantitative measures: gray value, linear attenuation coefficient, density resolution, attenuation of X‑rays.
• Image quality and limits: artefact, partial volume effect, slice thickness, region of interest (ROI), local CT (ROI CT).
• System and test objects: CT system (tomograph) and calibration phantom (standard).

The standard does not set performance thresholds; its requirement is to provide authoritative terms and definitions to ensure clarity in NDT CT communications and documents.

Applications

ISO 15708-1:2017 is used to:

• Standardize terminology in CT test procedures, reports and specifications for industrial NDT.
• Improve communication between CT system manufacturers, inspection service providers and end users.
• Support training materials and certification programs for CT operators and inspectors.
• Aid researchers, metrology labs and regulators in unambiguous reporting of CT results and methods.
• Provide a reference for writing and harmonizing other standards or technical documents involving CT imaging.

Who should use this standard

• NDT engineers and radiographers working with industrial CT
• CT system designers and manufacturers
• Quality assurance and inspection managers
• Standards developers, regulators and testing laboratories
• Technical writers and trainers producing CT procedures and documentation

Related standards and resources

• The ISO 15708 series (other parts cover methods and requirements for CT) - see ISO for the list of parts.
• ISO Online Browsing Platform and IEC Electropedia for standardized terminologies and cross-references.

Keywords: ISO 15708-1:2017, computed tomography terminology, NDT CT, radiation methods, CT vocabulary, CT imaging terms, beam hardening, attenuation coefficient, voxel, sinogram.