ISO 20785-2:2020

Overview - ISO 20785-2:2020 (Dosimetry for cosmic radiation, Part 2)

ISO 20785-2:2020 specifies minimum methods and procedures for characterizing the response of instruments used to determine the ambient dose equivalent (H(10))* for assessment of cosmic radiation in civilian aircraft. Part of the ISO 20785 series and issued as the second edition (2020), this standard addresses how to calibrate, test and document dosimetric devices so measurements at flight altitudes are traceable, reproducible and suitable for validating calculated crew exposures.

Key topics and technical requirements

• Instrument characterization: Procedures for determining dosimetric characteristics and calibration coefficients/factors under defined reference and non-reference conditions.
• Calibration fields and reference radiation: Definition and use of reference radiation fields, plus guidance on scattered radiation and effects of other radiation types.
• Uncertainty and traceability: Requirements for expressing measurement uncertainty consistent with ISO/IEC Guide 98-1 and 98-3 (GUM).
• Use of numerical simulations: Acceptance and limits for modeling instrument response to atmospheric particle spectra not fully covered by reference beams.
• Software controls: Development, testing and data-analysis requirements for instrument-related software and spreadsheet use.
• Performance testing and annexes: Practical notes on performance tests and informative annexes including representative particle fluence/energy distributions, recommended calibration fields, comparison measurements and charged-particle irradiation facilities.

Practical applications and users

ISO 20785-2:2020 is designed for:

• Primary and secondary calibration laboratories that establish traceable calibrations for aviation dosimeters.
• Radiation protection professionals and governmental agencies responsible for monitoring and regulating flight crew exposure.
• Airlines and aviation safety organizations that need validated measurement methods to support roster planning and regulatory compliance (for example, EU occupational exposure rules and the 1 mSv/year consideration).
• Manufacturers of dosimetric instruments who must characterize instrument response across the complex mixed radiation field present at flight altitudes.

Typical uses include validating calculated route doses, performing intercomparison measurements, establishing calibration services for personal or area dosimeters and documenting measurement uncertainty for regulatory reporting.

Related standards and references

• ISO 20785 series (other parts covering measurement protocols and dose assessment).
• ISO/IEC Guide 98-1 and ISO/IEC Guide 98-3 (GUM) for uncertainty of measurement.
• Guidance from international bodies referenced in the standard (e.g., ICRP recommendations) for context on occupational exposure to cosmic radiation.

Keywords: ISO 20785-2:2020, dosimetry, cosmic radiation, ambient dose equivalent, aircraft crew, instrument response, calibration, measurement uncertainty, radiation protection.