Flight-time equivalent dose

Flight-time equivalent dose (FED) is an informal unit of measurement of ionizing radiation exposure. Expressed in units of flight-time (i.e., flight-seconds, flight-minutes, flight-hours), one unit of flight-time is approximately equivalent to the radiological dose received during the same unit of time spent in an airliner at cruising altitude. FED is intended as a general educational unit to enable a better understanding of radiological dose by converting dose typically presented in sieverts into units of time. FED is only meant as an educational exercise and is not a formally adopted dose measurement.

Visual comparison of radiological exposure from daily life activities.
Visual comparison of radiological exposure from medical sources.

History

The flight-time equivalent dose concept is the creation of Ulf Stahmer, a Canadian professional engineer working in the field of radioactive materials transport. It was first presented in the poster session[1] at the 18th International Symposium of the Packaging and Transport of Radioactive Materials (PATRAM) held in Kobe, Hyogo, Japan where the poster received an Aoki Award for distinguished poster presentation.[2] In 2018, an article on FED[3] appeared in the peer-reviewed journal The Physics Teacher.

Usage

Flight-time equivalent dose is an informal measurement, so any equivalences are necessarily approximate. It has been found useful to provide context between radiological doses received from various every-day activities and medical procedures.

Dose calculation

FED corresponds to the time spent in an airliner flying at altitude required to receive a corresponding radiological dose. FED is calculated by taking a known dose (typically in millisieverts) and dividing it by the average dose rate (typically in millisieverts per hour) at an altitude of 10,000 m, a typical cruising altitude for a commercial airliner.

While radiological dose at cruising altitudes varies with latitude, for FED calculations, the radiological dose rate at an altitude of 10,000 m has been standardized to be 0.004 mSv/h,[4] about 15 times greater than the average dose rate at the Earth's surface. Using this technique, the FED received from a 0.01 mSv panoramic dental x-ray is approximately equivalent to 2.5 flight-hours; the FED received from eating one banana is approximately equal to 1.5 flight-minutes; and the FED received each year from naturally occurring background radiation (2.4 mSv/year[5]) is approximately equivalent to 600 flight-hours.

Radiological exposures and limits

For comparison, a list of activities (including common medical procedures) and their estimated radiological exposures are tabulated below. Regulatory occupational dose limits for the public and radiation workers are also included. Items on this list are represented pictorially in the accompanying illustrations.

List of radiologial exposures from various sources
ActivityEvent TypeDoseFED
Airport x-ray full body scansingular0.00001 mSv[6]9 flight-seconds
One hour of sun exposuresingular0.00004 mSv[5]36 flight-seconds
Household smoke detectorannual0.00008 mSv[7]1.2 flight-minutes
Living near a nuclear generating stationannual0.00009 mSv[7]1.3 flight-minutes
Eating one bananasingular0.0001 mSv[8]1.5 flight-minutes
Living near a coal generating stationannual0.0003 mSv[7]4.5 flight-minutes
Crowns or false teethannual0.0007 mSv[7]10.5 flight-minutes
Bone scan or extremity (arm) x-raysingular0.001 mSv[9]15 flight-minutes
One hour of air travelsingular0.004 mSv[4][10][11][12]1 flight-hour
Dental (intraoral) or knee x-raysingular0.005 mSv[9]1.2 flight-hours
Dental (panoramic) or shoulder x-raysingular0.01 mSv[9]2.5 flight-hours
Sleeping next to someoneannual0.02 mSv[13]5 flight-hours
Bone scan with CTsingular0.04 mSv[9]10 flight-hours
Living in a stone or brick buildingannual0.07 mSv[7]17.5 flight-hours
Chest or skull x-raysingular0.1 mSv[9]25 flight-hours
Smoking cigarettes (1/2 pack per day)annual0.18 mSv[14]45 flight-hours
Cervical spine x-raysingular0.2 mSv[9]50 flight-hours
Mammogramsingular0.4 mSv[9]100 flight-hours
Pelvic x-raysingular0.6 mSv[9]150 flight-hours
Abdomen or hip x-raysingular0.7 mSv[9]175 flight-hours
Public dose limitlimit1 mSv[15]250 flight-hours
Lumbar spine x-raysingular1.5 mSv[9]375 flight-hours
Background radiation in Toronto, CAannual1.6 mSv[5]400 flight-hours
Brain CT scansingular2 mSv[9]500 flight-hours
Background radiation - worldwide averageannual2.4 mSv[5]600 flight-hours
Flight crewannual3 mSv[4][10][11][12][16]750 flight-hours
Neck CT or calcium scoring CTsingular3 mSv[9]750 flight-hours
Background radiation in Winnipeg, CAannual4 mSv[5]1000 flight-hours
Thoracic angiography of heartsingular5 mSv[9]1250 flight-hours
Pelvic or chest CT scansingular6 mSv[9]1500 flight-hours
Barium enemasingular8 mSv[9]2000 flight-hours
Average Fukishima recovery workersingular12 mSv[17]3000 flight-hours
Abdominal angiography or aortographysingular12 mSv[9]3000 flight-hours
Coronary angioplasty or stent placementsingular15 mSv[9]3750 flight-hours
Coronary angiographysingular16 mSv[9]4000 flight-hours
Radiation worker dose limitlimit50 mSv[15]12,500 flight-hours
Pelvic vein embolizationsingular60 mSv[9]15,000 flight-hours
Transjugular intrahepatic portosystemic shunt placementsingular70 mSv[9]17,500 flight-hours
Astronaut on 6 month ISS missionsingular72 mSv[18]18,000 flight-hours
Lowest acute dose known to cause cancersingular100 mSv[19][20]25,000 flight-hours

See also

References
  1. Stahmer, U. 11 – 16 September 2016. Flight-Time Equivalent Dose - A Concept to Contextualize Radiological Dose. 18th International Symposium of the Packaging and Transport of Radioactive Materials (PATRAM). Kobe, Hyogo, Japan.
  2. Nuclear Waste Management Organization (2016). Engineer Wins Award for Best Poster. Retrieved 10 December 2021.
  3. Stahmer, U. (2018-10-24). "Using Flight-Time to Contextualize Radiological Dose". The Physics Teacher. 56 (8): 508–511. doi:10.1119/1.5064556. S2CID 125730267. Retrieved 2022-04-28.
  4. Friedberg, W; Copeland K (2011). "Ionizing Radiation in Earth's Atmosphere and in Space Near Earth" Civil Aerospace Medical Institute, Federal Aviation Administration, DOT/FAA/AM- 11/9.
  5. Grasty, R.L.; LaMarre, J.R. (2004-02-01). "The annual effective dose from natural sources of ionising radiation in Canada". Radiation Protection Dosimetry. 108 (3): 215–226. doi:10.1093/rpd/nch022. PMID 15031443. Retrieved 2022-04-28.
  6. "AAPM Report No. 217 Radiation Dose from Airport Scanners" (PDF). American Association of Physicists in Medicine. June 2013. Retrieved 26 April 2022.
  7. "Calculate your radiation dose". United States Environmental Protection Agency. 3 October 2014. Retrieved 2022-04-26.
  8. Mansfield, G. (1995-03-08). "Banana Equivalent Dose". RadSafe -- The International Radiation Protection (Health Physics) Mailing List. Retrieved 2022-04-28.
  9. Mettler, F.A.; Huda, W.; Yoshizumi, T.T.; Mahesh, M. (2008). "Effective Doses in Radiology and Diagnostic Nuclear Medicine: A Catalog". Radiology. 248 (1): 254–63. doi:10.1148/radiol.2481071451. PMID 18566177. Retrieved 2022-04-26.
  10. Reitz, G. (1993-05-01). "Radiation Environment in the Stratosphere". Radiation Protection Dosimetry. 48 (1): 5–29. doi:10.1093/oxfordjournals.rpd.a081837. Retrieved 2022-04-28.
  11. Shea, M.A.; Smart, D.F. (August 2001). Comment on Galactic Radiation Dose to Air Crews. 27th International Cosmic Ray Conference. Bibcode:2001ICRC...10.4071S.
  12. Bennett, L.G.I.; Lewis, B.J.; Bennett, M.J.; McCall, M.J.; Bean, M (2013). "A Survey of the Cosmic Radiation Exposure of Air Canada Pilots during Maximum Galactic Radiation Conditions in 2009". Radiation Measurements. 49 (1): 103–108. doi:10.1016/j.radmeas.2012.12.004. Retrieved 2022-04-28.
  13. Borham, D. (27 October 2010). "Human health and the biological effects of tritium in drinking water". Slide 16. Retrieved 2022-04-26.
  14. "Report No. 160 – Ionizing Radiation Exposure of the Population of the United States". National Council on Radiation Protection and Measurements. 3 March 2009. Retrieved 26 April 2022.
  15. ICRP, International Commission on Radiological Protection. "Dose limits". ICRPedia. ICRP. Retrieved 26 April 2022.
  16. Bailey, S. (2000). "Air crew radiation exposure – An overview" (PDF). Nuclear News. 43 (1): 32–40. Retrieved 2022-04-26.
  17. United Nations Environment Programme (2016). Radiation Effects and Sources. United Nations Environment Programme. doi:10.18356/b1749f17-en. ISBN 9789210599597.
  18. Cucinotta, F.A. (January 1, 2007). "Space Radiation Organ Doses for Astronauts on Past and Future Missions" (PDF). NASA Technical Reports Server. Retrieved 26 April 2022.
  19. "Radiation Health Effects". Canadian Nuclear Safety Commission. 3 February 2014. Retrieved 2022-04-26. However, studies to date have not been able to show any excess cancers or other diseases in people chronically exposed to radiation at doses lower than about 100 mSv.
  20. "Backgrounder on Biological Effects of Radiation". Biological Effects of Radiation. United States Nuclear Regulatory Commission. 2020-07-08. Retrieved 2022-04-28. The data show high doses of radiation may cause cancers. But there are no data to establish a firm link between cancer and doses below about 10,000 mrem (100 mSv – 100 times the NRC limit).
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