and Risk Anthony Waker Faculty of Energy Systems and Nuclear Science External Exposure The source is external to the body Types of Exposure CT Scanner A few to 10s of mSv per examination ID: 919912
Download Presentation The PPT/PDF document "Radiation Exposure, Effects" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Radiation Exposure, Effects and Risk
Anthony Waker
Faculty of Energy Systems and Nuclear Science
Slide2External Exposure
The source is external to the body
Types of Exposure
CT Scanner: A few to 10s of
mSv
per examination
Slide3Internal Exposure
The source is inside the body
Types of Exposure
Approximately 1
mSv
per year
Slide4Total Exposure is the sum of all external and all internal doses
Types of Exposure
Approximately 3
mSv
per year
Slide5Members of the public 1 mSv
per year
Nuclear Energy Workers 20 mSv per year (100 mSv in 5 years, 50 mSv in any one year)
Fukushima workers – legal limit has been raised to 250 mSv
Legal Limits o
f Exposure
Medical Radiation not counted
Slide6External doses
Calibrated Instruments and dosimeters
Measuring Dose
Calibrated instruments and dosimeters give a direct reading of the radiation dose to the individual
Slide7Internal Doses
Whole body counters and Bioassay
Measuring Dose
Whole body counters and bioassay are used to determine the intake of radioisotopes; what follows is a complicated calculation to convert an intake into a dose.
Slide8Principal Concerns at moderate to low dose (
mSv
to a few Sv)Cancer
Hereditary Disease
Radiation Effects on the Fetus
EffectsThe risk increases with dose
Slide9Principal Concerns at high dose (1 Sv
and up)
Radiation SicknessBone marrow damage
Gastrointestinal damage
Effects
The severity increases with dose
Slide10Risk to humans derived from
Atomic Bomb Survivors
(Hiroshima and Nagasaki Life Span Study)Medically exposed groups
(ankylosing
spondylitis;
repeated fluoroscopic examination of tuberculosis patients in Massachusetts and Nova Scotia)Occupationally exposed groups (radium dial-painters, uranium miners, former Soviet Union plutonium workers)Risks at moderate and low doses
Slide11Current Assessment of Risk
Cancer (
4 to 10% per Sv)
Hereditary Disease (
1/10 th of fatal cancer risk
)Radiation Effects on the Fetus (life-time cancer risk 20% per Sv)Risks at moderate and low doses
Slide12Cancer risk estimates apply to populations
not to
individualsRisks at moderate and low doses
Slide13Risks at moderate and low doses
Cancer risks attributable to low doses of ionizing radiation: Assessing what we really know
PNAS
November 25, 2003 vol. 100 no. 24 13761–13766
What is the lowest dose of X-ray or gamma ray radiation for which good evidence exists of increased cancer risk in humans………
Slide14Risks at moderate and low doses
Cancer risks attributable to low doses of ionizing radiation: Assessing what we really know
PNAS November 25, 2003 vol. 100 no. 24 13761–13766
………the epidemiological data suggests that it is approximately 10-50 mSv for an acute exposure and 50–100
mSv for a chronic exposure
Slide15Effects at high dose result from the killing of stem cells that are used to supply replacement cells in the blood and for the lining of the intestines
Effects at High Dose
Slide16Whole-body Irradiation and Radiation Lethality
Slide17Acute Radiation Syndrome – Medical Intervention
Slide18External exposures
Limit the time of exposure
Rotation of workers (shifts)Increase the distance from the sourceShielding (put something between you and the source)
Exposure mitigation -workers
Fukushima workers will be using all these measures of reducing dose
Slide19Internal exposures
Protective clothing and breathing apparatus
Prevent spreading contamination by not moving out of contaminated area without changing protective clothing and boots; showers
Exposure mitigation - workers
Slide20Very High Total Exposures
Nursing
Anti-bioticsBlood transfusionsBone marrow transfusions
Exposure mitigation - workers
Slide21External Exposure
Distance (exclusion zones and evacuation plans)
Internal ExposureStaying out of the plume (exclusion)Staying indoorsPreventing spread of contaminationUsing Potassium Iodide
Exposure mitigation - Public