Flight-time equivalent dose

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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.

Contents

Visual comparison of radiological exposure from daily life activities. Radiological exposure from daily life.png
Visual comparison of radiological exposure from daily life activities.
Visual comparison of radiological exposure from medical sources. Radiological exposure from medical sources.png
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 scan singular0.00001 mSv [6] 9 flight-seconds
One hour of sun exposure singular0.00004 mSv [5] 36 flight-seconds
Household smoke detector annual0.00008 mSv [7] 1.2 flight-minutes
Living near a nuclear generating station annual0.00009 mSv [7] 1.3 flight-minutes
Eating one bananasingular0.0001 mSv [8] 1.5 flight-minutes
Living near a coal generating station annual0.0003 mSv [7] 4.5 flight-minutes
Crowns or false teeth annual0.0007 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 CT singular0.04 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
Mammogram singular0.4 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 enema singular8 mSv [9] 2000 flight-hours
Average Fukishima recovery workersingular12 mSv [17] 3000 flight-hours
Abdominal angiography or aortography singular12 mSv [9] 3000 flight-hours
Coronary angioplasty or stent placementsingular15 mSv [9] 3750 flight-hours
Coronary angiographysingular16 mSv [9] 4000 flight-hours
Average annual radiation worker dose limitlimit20 mSv [18] 5000 flight-hours
Maximum annual radiation worker dose limitlimit50 mSv [15] 12,500 flight-hours
Pelvic vein embolization singular60 mSv [9] 15,000 flight-hours
Transjugular intrahepatic portosystemic shunt placementsingular70 mSv [9] 17,500 flight-hours
Astronaut on 6 month ISS missionsingular72 mSv [19] 18,000 flight-hours
Lowest acute dose known to cause cancer singular100 mSv [20] [21] 25,000 flight-hours

See also

Related Research Articles

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References

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  2. Nuclear Waste Management Organization (2016). Engineer Wins Award for Best Poster. Retrieved 10 December 2021.
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