Overview
ISO 13304-2:2020 - "Radiological protection - Minimum criteria for electron paramagnetic resonance (EPR) spectroscopy for retrospective dosimetry of ionizing radiation - Part 2: Ex vivo human tooth enamel dosimetry" defines minimum criteria for performing X‑band EPR dosimetry on human tooth enamel. The standard establishes requirements for quality assurance (QA), quality control (QC), performance evaluation, and inter-laboratory comparability when estimating absorbed dose in tooth enamel (hydroxyapatite). It is focused on ex vivo measurements and does not cover organ or whole‑body dose calculations.
Key topics and technical requirements
ISO 13304-2 specifies procedural and technical elements required to produce reliable EPR dosimetry results:
- Measurement apparatus: minimum specifications for X‑band EPR spectrometers, microwave bridge, magnetic field and resonator characteristics to ensure adequate sensitivity and stability.
- Sample preparation: controlled procedures for enamel separation, applicable grain size, sample loading and positioning to minimize variability.
- Spectrum acquisition: parameters and conditions for recording EPR spectra (power, field sweep, modulation, accumulation, resolution) and management of intrinsic signals from resonator or sample tube.
- Signal evaluation and calibration: methods to assess radiation‑induced signal (RIS), convert RIS intensity to absorbed dose, and establish dose‑response calibration using irradiated standards.
- Uncertainty and performance testing: guidance for calculating dose uncertainty, minimum detectable dose, and laboratory performance checks including inter‑laboratory comparisons.
- QA/QC, documentation and responsibilities: requirements for laboratory QA/QC programs, minimum documentation, and delineation of customer vs. laboratory responsibilities.
- Ethics and safety: confidentiality/ethical considerations, and laboratory safety requirements (magnetic field, electromagnetic, chemical, biological and optical safety).
Applications and practical value
ISO 13304-2 is intended to improve the reliability and comparability of retrospective dose estimates obtained from human tooth enamel using EPR. Practical uses include:
- Radiological incident response and casualty management
- Forensic dose reconstruction and legal/administrative evidence
- Validation of epidemiological dosimetry and radiobiological studies
- Research into long‑term exposures where historical dosimetry is incomplete
- Inter‑laboratory proficiency testing and method standardization
Who should use this standard
- EPR dosimetry laboratories performing ex vivo tooth enamel measurements
- Radiation protection agencies and emergency response teams
- Forensic and clinical laboratories involved in dose reconstruction
- Researchers in radiological epidemiology and dosimetry method development
- Accreditation bodies and QA managers ensuring ISO/IEC 17025 conformity
Related standards
- ISO 13304‑1 (general EPR dosimetry principles) and other parts of the ISO 13304 series
- ISO/IEC 17025 (competence of testing and calibration laboratories)
- Relevant IAEA technical reports on EPR dosimetry (for additional background and methodology)
Keywords: ISO 13304-2, EPR dosimetry, electron paramagnetic resonance, tooth enamel, retrospective dosimetry, X‑band EPR, absorbed dose, radiological protection, QA/QC, calibration, dose uncertainty.