ICRU Report 84

Reference Data for the Validation of Doses from Cosmic-Radiation Exposure of Aircraft Crew

Prepared jointly with ICRP
Abstract - Aircraft crews are exposed to elevated levels of cosmic radiation of galactic and solar origins and secondary radiations produced in the atmosphere, the aircraft, and its contents. The ICRP has recommended that exposures of aircraft crew to cosmic radiation in the operation of commercial jet aircraft be included as occupational exposure. The radiation field inside an aircraft is to a large extent uniform, and doses are generally predictable, with the exception of rare, intense, highenergy solar-particle events. Events comparable to unplanned exposure in other radiation workplaces cannot normally occur. The routine assessment of annual doses of aircraft crew is based on calculated values of effective-dose rate in conjunction with staff-roster information. In routine radiation protection, traceable measurements are the basis of the overall system of dose assessment, and it is generally accepted that methods of annual dose assessment for aircraft crew based on radiationtransport calculations of effective-dose rates should be periodically verified by measurement. The purpose of this Report is to provide reference data derived from measurements against which the results of routine methods of assessing annual doses using calculations can be compared (benchmarked) for validation purposes. The reference values of ambient-dose-equivalent rate for exposure to cosmic radiation of galactic origins in aircraft at aviation altitudes cover the range of geomagnetic latitudes of relevance, for three different time periods within the most recently completed solar cycle 23. The relationships between ambient dose equivalent and effective dose are given, allowing the calculation of effective dose from values of ambient dose equivalent. These reference values should facilitate international harmonization of dose assessments for aircraft crew in terms of effective dose.