Overview of research on aircraft crew dosimetry during the last solar cycle

Characterization of Thermoluminescent Dosimeters for Neutron Dosimetry at High Altitudes

Neutrons constitute a significant component of the secondary cosmic rays and are one of the most important contributors to natural cosmic ray radiation background dose. The study of the cosmic ray neutrons' contribution to the dose equivalent received by humans is an interesting and challenging task for the scientific community. In addition, international regulations demand assessing the biological risk due to radiation exposure for both workers and the general population. Because the dose rate due to cosmic radiation increases significantly with altitude, the objective of this work was to characterize the thermoluminescent dosimeter (TLDs) from the perspective of exposing them at high altitudes for longtime neutron dose monitoring. The pair of TLD-700 and TLD-600 is amply used to obtain the information on gamma and neutron dose in mixed neutron-gamma fields due to the present difference in 6Li isotope concentration. A thermoluminescence dosimeter system based on pair of TLD-600/700 was characterized to enable it for neutron dosimetry in the thermal energy range. The system was calibrated in terms of neutron ambient dose equivalent in an experimental setup using a 241Am-B radionuclide neutron source coated by a moderator material, polyethylene, creating a thermalized neutron field. Afterward, the pair of TLD-600/700 was exposed at the CERN-EU High-Energy Reference Field (CERF) facility in Geneva, which delivers a neutron field with a spectrum similar to that of secondary cosmic rays. The dosimetric system provided a dose value comparable with the calculated one demonstrating a good performance for neutron dosimetry.

Radiation damage and radioprotectants: new concepts in the era of molecular medicine

Exposure to ionising radiation results in mutagenesis and cell death, and the clinical manifestations depend on the dose and the involved body area. Reducing carcinogenesis in patients treated with radiotherapy, exposed to diagnostic radiation or who are in certain professional groups is mandatory. The prevention or treatment of early and late radiotherapy effects would improve quality of life and increase cancer curability by intensifying therapies. Experimental and clinical data have given rise to new concepts and a large pool of chemical and molecular agents that could be effective in the protection and treatment of radiation damage. To date, amifostine is the only drug recommended as an effective radioprotectant. This review identifies five distinct types of radiation damage (I, cellular depletion; II, reactive gene activation; III, tissue disorganisation; IV, stochastic effects; V, bystander effects) and classifies the radioprotective agents into five relevant categories (A, protectants against all types of radiation effects; B, death pathway modulators; C, blockers of inflammation, chemotaxis and autocrine/paracrine pathways; D, antimutagenic keepers of genomic integrity; E, agents that block bystander effects). The necessity of establishing and funding central committees that guide systematic clinical research into evaluating the novel agents revealed in the era of molecular medicine is stressed.

Routine individual monitoring of aircraft crew exposure; Czech experience and results 1998-2008

Individual monitoring of aircrew of airline operators registered in the Czech Republic has been performed since 1998. In this work, annual effective doses and annual collective effective doses of aircrew from occupational exposure in the period from 1998 to 2008 are presented, methods used for their evaluation and verification are described, and general trends observed in the data are discussed. Annual effective doses were calculated using the computer code CARI from flight schedules provided by airline operators and typical flight profiles. The method was verified via a comparison with (i) measurements using different types of detectors and (ii) calculations using the CARI and EPCARD codes with actual flight data. It was found that average annual effective doses in the period from 1998 to 2008 were in the range from 1.2 to 2.0 mSv and followed the trend of the solar cycle. Annual collective effective doses increased from 1.4 manSv in 1998 to 4.1 manSv in 2008 as the number of aircrew increased from 857 to 2158 during this period. Combined relative uncertainties (coverage factor ) of reported individual and collective effective doses were ∼ 25 %, which is well within the range given by the factor of 1.5. More work is needed to achieve a higher accuracy of this estimate.

Workplace monitoring of mixed neutron-photon radiation fields and its contribution to external dosimetry

Workplace monitoring is a common procedure for determining measures for routine radiation protection in a particular working environment. For mixed radiation fields consisting of neutrons and photons, it is of increased importance because it contributes to the improved accuracy of individual monitoring. An example is the determination of field-specific correction factors, which can be applied to the readings of personal dosemeters. This paper explains the general problems associated with individual dosimetry of neutron radiation, and describes the various options for workplace monitoring. These options cover a range from the elaborate field characterisation using transport calculations or spectrometers to the simpler approach using area monitors. Examples are given for workplaces in nuclear industry, at particle accelerators and at flight altitudes.