ISO 21243:2022

Overview

ISO 21243:2022 - Radiation protection - Performance criteria for laboratories performing initial cytogenetic dose assessment of mass casualties in radiological or nuclear emergencies - General principles and application to dicentric assay - provides minimum organizational and operational requirements for performing an expedited dicentric assay for initial dose assessment in mass-casualty radiological or nuclear events. The standard focuses on rapid, quality‑assured cytogenetic categorization of exposed individuals using mitogen-stimulated peripheral blood lymphocytes to support early clinical decision-making and triage.

Key topics and requirements

• Scope & purpose: Guidance for initial (rapid) dicentric assay use in mass-casualty incidents to estimate approximate absorbed dose and support clinical triage.
• Organizational responsibilities: Laboratory preparedness, pre‑planning, confidentiality, handling of biological dosimetry requests and reporting.
• Laboratory network design: Roles and responsibilities of lead and associate laboratories; procedures for coordinated surge capacity and network operation.
• Biological dosimetry process: Sample collection, transport integrity, simplified/expedited processing and validated scoring strategies for initial assessment.
• Quality assurance and quality control (QA/QC): Defined performance checks covering sample integrity, instrumentation, scoring, dose estimation and confidence intervals, report generation and data security.
• Performance checks: Regular verification of protocols, scoring thresholds (including manual scoring guidance), and network performance to ensure reproducible, defensible dose estimates.
• Interpretation guidance: Consideration of whole‑body vs. inhomogeneous exposures, uncertainty communication and when acute exposure assumptions may not apply (note: for low LET radiation below ~0.3 Gy linearity is generally assumed).
• Automation and validation: Semi‑ or fully automated methods may be used if validated and documented by the laboratory.

Applications and users

ISO 21243:2022 is intended for:

• National and regional biological dosimetry laboratories and cytogenetic labs involved in emergency response
• Lead laboratories coordinating multi‑laboratory networks for surge capacity
• Emergency planners, public health authorities, medical responders and hospital laboratories seeking validated procedures for rapid dose categorization
• Organizations developing training, drills and stockpiling strategies for radiological/nuclear mass-casualty preparedness

Practical uses include rapid triage support to identify non-exposed individuals, low/moderately exposed persons who need monitoring, and highly exposed patients requiring urgent treatment.

Related standards

• ISO 19238 (technical aspects of dicentric assay)
• ISO 17099 (cytokinesis-block micronucleus assay guidance)
• ISO/IEC 17025 (laboratory competence)
• ISO Guide 98 and ISO 5725 (uncertainty and accuracy guidance)

Keywords: ISO 21243:2022, dicentric assay, biological dosimetry, radiation protection, cytogenetic dose assessment, mass casualty, laboratory network, quality assurance, radiological emergency.