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Year : 2016  |  Volume : 39  |  Issue : 4  |  Page : 233-235  

Summary of ICRP publications, meeting of members of ICRP and IARP, and new RPEJ publication award announcement


Associate Editor, RPE, Internal Dosimetry Section, Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, . E-mail:, India

Date of Web Publication13-Feb-2017

Correspondence Address:
D D Rao
Associate Editor, RPE, Internal Dosimetry Section, Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/rpe.RPE_3_17

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How to cite this article:
Rao D D. Summary of ICRP publications, meeting of members of ICRP and IARP, and new RPEJ publication award announcement. Radiat Prot Environ 2016;39:233-5

How to cite this URL:
Rao D D. Summary of ICRP publications, meeting of members of ICRP and IARP, and new RPEJ publication award announcement. Radiat Prot Environ [serial online] 2016 [cited 2020 Sep 19];39:233-5. Available from: http://www.rpe.org.in/text.asp?2016/39/4/233/199971

ICRP. Radiological protection from cosmic radiation in aviation. ICRP Publication 132. Ann. ICRP 2016;45(1):1-48.

Following are the key points of new International Committee on Radiological Protection (ICRP) Publication 132 on the subject of radiological protection from cosmic radiation in aviation. The publication has four sections beginning with, (1) introduction, (2) characteristics of exposure to cosmic radiation in aviation, (3) the ICRP system of protection for passengers and aircraft crew, (4) implementation of the ICRP system of protection, and (5) conclusions. The publication begins with an editorial titled “TAKING FLIGHT IN A SEA OF RADIATION.”

Cosmic radiation mainly comes from the high-energy particles that come from outside the solar system (galactic cosmic radiation) and from the sun (solar cosmic radiation) primarily consisting of high energy protons and the resulting secondary electrons, neutrons, positrons, muons, and gamma photons.

The commission considers the exposure to cosmic radiation including that produced by solar flares, as an existing exposure situation. The exposure of aircraft passengers including both occupational and frequent flyers for personal or professional purposes should be considered as public exposure. The exposure of aircraft crew should be treated as occupational exposure. The commission recommends a graded approach for the practical implementation of protection strategy based on the flight frequency of the individuals. It recommends that the management of aircraft should inform the aircraft crew individually about the cosmic radiation through an education program, assess their doses, and record the individual and cumulative doses. These data should be made available to the individuals, and the records should be kept for a minimum period of expected lifetime of the individuals.

For most radiological protection purposes, properly validated computer calculation program is considered adequate for the assessment of dose to aircraft crew.

The aircraft cruising at an altitude, typically of >10,000 m, the dose rate can reach 7 µSv/h (>150 times the level of exposure to cosmic radiation at sea level), and it increases as the altitude increases. At normal aircraft altitudes and at the equator, electrons/positrons and neutrons are the main components in dose, followed by protons, while at higher latitudes, the dose is mainly from neutrons. The effective doses for three flight routes estimated with a dedicated computer code are: (1) transatlantic flight: Paris–New York 60 µSv (6.8 µSv/h); (2) transequatorial flight: Colombo–Jakarta 9.7 µSv (2 µSv/h); and (3) transpolar flight: Beijing–Chicago 82 µSv (6.8 µSv/h). A review of the exposure of aircraft crew in Europe indicated that the average annual effective dose varies from 1 mSv for the airline of the Czech Republic to 2.5 mSv for airlines from Finland and Sweden. The highest maximum annual effective dose is approximately 6–7 mSv for airlines from Denmark, Germany, and Finland. The average effective dose for aircraft crew in the USA is comparable and was estimated to be 3.1 mSv for 2006.

Epidemiological studies of aircraft crew have also been conducted over the past 25 years. The early studies were investigations of pilots from Canada, the UK, and Japan. With regard to cancer, pilots (historically, virtually all pilots were male) showed reduced cancer mortality compared with the general population; this reduction is often observed in occupational cohorts as a healthy worker effect. However, certain specific types of cancers, namely melanoma and brain cancer, seem to be elevated in aircraft crew.

ICRP. The ICRP computational framework for internal dose assessment for reference adults: Specific absorbed fractions. ICRP Publication 133. Ann. ICRP 2016;45(2):1-74.

Internal dose is one of the most sophisticated aspects of radiological protection. Equivalent doses to organs and tissues cannot be measured directly, and they need to be assessed mathematically based on the estimates of the radionuclide intake, mainly by inhalation or ingestion or injection. Internal dose, which is always a committed dose, will be received over time as a result of radionuclides residing in the body. ICRP provides effective dose coefficients (Sv/Bq), which when multiplied by the activity intake (Bq) gives the committed effective dose (Sv). These effective dose coefficients are derived using the biokinetic models (gives the distribution of inhaled/ingested radionuclides), nuclear decay data (gives the energy of radiation), and the anatomical and physical data and computational phantom (gives absorbed fraction).

Absorbed fraction is defined as the fraction of radiation energy emitted from a source organ that is absorbed in a target organ. These are generated computationally using Monte Carlo transport codes with complex geometries of computational phantoms. Specific absorbed fraction (SAF) is the absorbed fraction divided by the mass of target tissue.

This publication presents reference values of the SAFs for internally emitted photons, electrons, and alpha particles, as well as fission-spectrum neutrons associated with radionuclides that decay by spontaneous fission. The majority of SAF values given in this publication are derived from Monte Carlo radiation transport simulations in Reference Adult Male and Reference Adult Female computational phantoms. Additional SAF values for electron and alpha particles are taken from publication 66 for the Human Respiratory Tract Model. In this publication, new SAF values for electron and alpha particles are given for the Human Alimentary Tract Model that supersedes those given in publication 100. SAF values given in this publication are calculated as the quotient of the absorbed fraction and the target tissue mass. Values of reference target tissue masses used in SAF calculations are listed in Annex A of the publication. Table A.3 contains the source region definitions and their associated masses for both the Reference Adult Male and Reference Adult Female.

The reference computational phantoms are digital three-dimensional representations of human anatomy and are based on human computed tomographic data. The reference computational phantoms (or models) were constructed by modifying the voxel models of two individuals (Golem and Laura) whose body height and mass closely resembled the reference data. The phantoms contain all target regions relevant to the assessment of human exposure to ionizing radiation for radiological protection purposes, i.e., all organs and tissues that contribute to effective dose. The male reference computational phantom consists of approximately 1.95 million tissue voxels, resulting in a body height of 1.76 m and the body mass of 73 kg. The female reference computational phantom consists of approximately 3.89 million tissue voxels, resulting in a body height of 1.63 m and the body mass of 60 kg.

The electron gamma shower code system EGSnrc version v4-2-3-0 has been used for calculations of photon and electron absorbed fractions in this publication for reporting corresponding SAFs over the energy range of 10 keV to 10 MeV. Values of SAF below 10 keV were determined through interpolation to limiting values.

The Los Alamos National Laboratory Monte Carlo radiation transport code, Monte Carlo N-Particle eXtended version 2.6.0 has been used for calculations of neutron absorbed fraction. The energy range considered in the present calculation is <20 MeV.

The alpha, electron, photon, and neutron SAF files for the adult male and female are available for download from www.icrp.org. The files have a common structure and are formatted for use as direct access files.

Meeting of International Committee on Radiological Protection and Indian Association for Radiation Protection Members (www.icrp.org).

Members of ICRP Committee 1 and Indian Association for Radiation Protection (IARP) Executive Committee have met on the sidelines of International Conference on Radiation Biology (2016) at Chennai on November 11, 2016. The open panel discussion was initiated by Dr. Christopher Clement, Scientific Secretary, ICRP and Dr. B. Venkataraman, Vice President, IARP and Director, HS and EG, IGCAR. Several issues in respect of radiological protection at workplaces, the inappropriate use of cancer risk coefficients for assessment of risk to individuals for trivial environmental exposures, possible setting of some kind of threshold doses for risk assessment, and use of enormous amount of published epidemiological data available from high background regions of India were discussed. It was pointed out that integration of both the biological and epidemiological data is being considered for generating dose-response curves. More and more molecular epidemiological studies are needed to be launched worldwide for the collection of further scientific data. The meeting ended with the invitation of the ICRP Committee members to be part of future IARP conference during early 2018.






 

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