ISO 32679:2024

Overview

ISO 32679:2024 - Non-destructive testing - Radiographic testing - Determination of the size of industrial radiographic gamma sources describes a radiographic X‑ray method to measure the size of industrial gamma sources (≥ 0.5 mm) made from Ir‑192, Yb‑169, Se‑75 or Co‑60. The standard defines test alignment, film and digital measurement procedures, digital detector requirements and reporting. Typical measurement accuracy is ±10% (commonly not better than ±0.1 mm). The measured projected size is corrected by a geometrical magnification factor to obtain the true source dimension.

Key topics and technical requirements

• Scope of measurement: Source sizes ≥ 0.5 mm; method can be validated for other radionuclides.
• Test alignment and magnification: X‑ray source, gamma source and detector geometry are specified; the projected size is corrected using the magnification factor ((a+b)/a).
• Measurement methods:
  • Film radiography with optical magnification and graticule for direct measurement.
  • Digital radiography (CR or DDA) using image‑processing profiles to determine source projection.
• Digital detector requirements:
  • Pixel pitch ≤ 50 μm and at least 40× smaller than the nominal source size.
  • Basic spatial detector resolution (SRb) < 1/20 of the nominal source size.
  • Signal‑to‑noise ratio (SNR) in free beam area > 100; SNR measurement per ASTM E2597 (DDA) or ISO 16371‑1 (CR).
• Image quality controls: Contrast-to-noise criteria, use of reference objects (steel/tungsten cylinder or guide‑tube diameter) to calibrate pixel size and magnification.
• Reporting: Required items include identification of source/holder and activity, geometry (a, b, magnification), X‑ray parameters, detector details, measured size d, date and tester identification.

Applications and users

• Practical for NDT laboratories, industrial radiography service providers, gamma source manufacturers, and regulatory/quality assurance organizations that need to:
  • Validate manufacturing and assembly of encapsulated gamma sources.
  • Monitor source shape and dimension after insertion into holders.
  • Calculate image unsharpness and set appropriate source‑to‑object distances for radiographic inspection.
• Helps improve image quality control, traceability and conformity of gamma radiography operations.

Related standards

• ISO 19232‑5 - image unsharpness determination (duplex wire IQI)
• ISO 16371‑1 - computed radiography (CR) system classification
• ASTM E1114 - Ir‑192 source size measurement and source characterization
• ASTM E2002 - image unsharpness and spatial resolution practice
• ASTM E2597/E2597M - DDA manufacturing & SNR characterization

Keywords: ISO 32679:2024, radiographic testing, gamma source size, non‑destructive testing, industrial radiography, Ir‑192, Co‑60, digital detectors, computed radiography, image unsharpness.