ISO 11929-2-2019 PDF

Full title and description

Determination of the characteristic limits (decision threshold, detection limit and limits of the coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 2: Advanced applications (ISO 11929-2:2019). This part provides procedures and guidance for calculation of decision thresholds, detection limits and coverage-interval limits for non‑negative ionizing‑radiation measurands derived from counting measurements and associated evaluation models, including effects of calibration, sample treatment and other influencing quantities.

Abstract

ISO 11929-2:2019 extends the ISO 11929 series to advanced applications by applying the GUM Supplement 1 (Monte Carlo) approach and related uncertainty evaluation techniques to counting measurements with preselection of time or counts. It covers calculation of the decision threshold, detection limit and limits of the coverage interval for measurands that arise from gross and background count rates (for example net count rate or net activity) and that may involve additional model parameters (calibration factors, sample treatment corrections, etc.). The document includes explanatory notes on counting‑measurement statistics and Bayesian considerations, and points to numerical tools and supporting examples given across the ISO 11929 series.

General information

• Status: Withdrawn (replaced by ISO 11929-2:2025).
• Publication date: 13 February 2019 (Edition 2).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 17.240 — Radiation measurements.
• Edition / version: Edition 2 (2019).
• Number of pages: 40.

Scope

Specifies procedures for determining the decision threshold, the detection limit and the limits of the coverage interval for non‑negative ionizing radiation measurands evaluated from counting measurements (with time or count preselection). The scope covers measurands formed from gross and background count rates and additional evaluated quantities (e.g., calibration factors, chemical/physical sample treatments), treatment of uncertainties using the GUM Supplement 1 (Monte Carlo) methodology, and explanatory notes on counting statistics and Bayesian aspects relevant to advanced measurement situations.

Key topics and requirements

• Clear definitions and procedures for decision threshold, detection limit and coverage‑interval limits for non‑negative measurands.
• Application of the GUM Supplement 1 (Monte Carlo) approach for uncertainty propagation in counting measurements.
• Treatment of models where the measurand depends on gross and background counts plus calibration and correction factors.
• Handling of correlations and covariances between input quantities where applicable.
• Guidance on Bayesian considerations and when Bayesian reasoning may assist assessment.
• Advice on implementation, including numerical/Monte Carlo computation and references to example software/tools.
• Emphasis on reporting and use in conformity assessment, laboratory reporting and method validation.

Typical use and users

Used by metrology and testing laboratories, environmental and radiological monitoring organisations, nuclear industry laboratories, instrument manufacturers, accreditation bodies and regulators. Typical applications include laboratory detection‑limit calculations for gamma/alpha/beta counting, evaluation of sample activity, method validation, and routine reporting where demonstrated traceability and transparent uncertainty treatment are required.

Related standards

ISO 11929-1 (basic/elementary applications), ISO 11929-3 (unfolding and spectrometric/multi‑channel applications), ISO 11929-4 (application guidance and examples); earlier ISO 11929:2010; related measurement and radiological standards such as ISO 18589, ISO 9696, ISO 9697, ISO 9698, ISO 10703, ISO 7503, ISO 28218 and other guidance on measurement uncertainty (JCGM/GUM and GUM Supplement 1).

Keywords

decision threshold; detection limit; coverage interval; ionizing radiation; counting measurements; measurement uncertainty; GUM Supplement 1; Monte Carlo; net count rate; calibration; radiological metrology; ISO 11929 series.

FAQ

Q: What is this standard?

A: ISO 11929-2:2019 is Part 2 of the ISO 11929 series that gives advanced procedures for calculating decision thresholds, detection limits and coverage‑interval limits for ionizing‑radiation measurements evaluated from counting data.

Q: What does it cover?

A: It covers evaluation models where the measurand is derived from gross and background counts (and additional quantities), rigorous uncertainty propagation using the GUM Supplement 1 (Monte Carlo) approach, treatment of correlations, and explanatory notes on counting‑measurement statistics and Bayesian aspects.

Q: Who typically uses it?

A: Radiation metrologists, testing and environmental monitoring laboratories, nuclear industry analysts, instrument vendors, accreditation bodies and regulatory authorities involved in detection‑limit assessments and uncertainty reporting.

Q: Is it current or superseded?

A: ISO 11929-2:2019 was published 13 February 2019 and has been withdrawn and replaced by ISO 11929-2:2025 (the 2025 edition). Users should refer to the 2025 edition for the current requirements and practice.

Q: Is it part of a series?

A: Yes — ISO 11929 is a multi‑part series. Key parts are ISO 11929-1 (elementary applications), ISO 11929-2 (advanced applications — this document), ISO 11929-3 (unfolding/multi‑channel spectrometric methods) and ISO 11929-4 (application guidance and examples).

Q: What are the key keywords?

A: decision threshold, detection limit, coverage interval, counting measurements, measurement uncertainty, Monte Carlo (GUM Supplement 1), ionizing radiation, net activity, calibration corrections.