basic radiation training for responders to radiological incidents basics of radiation ma department...
TRANSCRIPT
Basic Radiation Training for Responders to
Radiological Incidents
BASICS OF RADIATION
MA Department of Public Health-Radiation Control Program
Thomas F. O’Connell
Telephone: 617.983.6891
email: thomas.f.o’[email protected]
July 2002
MA Department of Public Health
Radiation Control Program
174 Portland Street, 5th Fl. Boston, MA
617.727.6214
Emergency Line
617.727.9710
Decay
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4He NucleusEjected from Nucleus
has a discrete energy that can be measured and related to the parent
Most of the energyassociated with
Decay
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Either too many neutrons or too many protons
Take away + charge and change a proton into a
neutron
Take away - charge and change a neutron into a proton
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antineutrino
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neutrino
Three products share energy – therefore beta has a continuous range of energies
Decay• Emission of a photon from the nucleus• Often occurs after or when nucleus is in an excited state• Given off with discrete energies• Can measure photon energy and possibly identify parent
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neutrino
Gamma Photon
Half-Life Illustration
At = Aoe-t or Nt= Noe- t
Beginning Activity or Number of Nuclei
Time (t)Act
ivity
(A
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Num
ber
of N
ucle
i (N
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How fast the curve changes (short half-life) (long half-life)
Radiation by Numbers
Radioactivity Absorbed Dose Dose Equivalent Exposure
Common Units curie (Ci) rad rem Roentgen (R)
SI Units becquerel (Bq) gray (Gy) sievert (Sv) coulomb/kilogram (C/kg)
Conversion Equivalence
1 curie = 3.7 x 1010 disintegrations per sec. 1 becquerel = 1 disintegration per sec.
1 millicurie (mCi) equal 37 megabecquerels (MBq)
1 rad equal 0.01 gray (Gy)
1 rem equal 0.01 sievert (Sv)
1 roentgen (R) equal 0.000258 coulomb/kilogram (C/kg)
megabecqerel (MBq) equal 0.027 millicuries (mCi)
1 gray (Gy) equal 100 rad
1 sievert (Sv) equal 100 rem
1 coulomb/kilogram (C/kg) equal 3,876 roentgens (R) Conversion Factors
To Convert From To Multiply By
curies (Ci) becquerels (Bq) 3.7 x 1010
millicuries (mCi) megabecquerels (Mbq) 37
microcuries (µCi) megabecquerels (Mbq) 0.037
millirads (mrad) milligrays (mGy) 0.01
Millirems (mrem) microsieverts (µSv) 10
milliroentgens (mR) microcoulombs/kilogram (µC/kg) 0.258
becquerels (Bq) curies (Ci) 2.7 x 10-11
megabecquerels (Mbq) millicuries (mCi) 0.027
megabecquerels (Mbq) microcuries (µCi) 27
milligrays (mGy) millirads (mrad) 100
microsieverts (µSv) millirems (mrem) 0.1
microcoulombs/kilogram (µC/kg) milliroentgens (mR) 3.88
• Time:reduce time spent in radiation area
• Distance:stay as far away from the radiation source as possible
• Shielding:interpose appropriate materials between the source and your body
Three Steps for Reducing Radiation Exposure
Shielding for , and
BASIC CONCEPT is to:
Place materials between the source and person to absorb some or all of the radiation
radiation: no shield required for external exposures; clothing, dead skin layer stops ’s,
radiation: ranges of meters in air; some can penetrate dead skin layer; thin plexiglass shields adequate, bunker gear effective for low energy
x and radiation: highly penetrating, best shields are dense materials (lead), vehicles can be used as shields
Shielding for , and
Control of DistanceRemote Operation
manipulating devices, remote handling tools
Moving Away from Sourcesremain near a source only when necessary
treat medical needs of patient/victim first
Secure and Remove Other Radiation Sourceswaste containers at Hot Zone/Cold Zoneother unnecessary sources
Control of distance
Control of Time
• Practice Mission in Background/Low Dose Area
• Spend Down Time in Low Dose Location
• (Dose Rate)(Time) = Dose• 10 mR/hr x ½ Hour = 5 mR• Use Respirators to Minimize
Internal Intake
Good Practices Include:
Restrict AccessLimit PersonnelPost AreasPost ProceduresBuddy System
Be Aware of Your Radiation Environment
Methods for Controlling External Exposure
Decontamination
To Make Safe by Removing the Unwanted Materials
Chemical Decon Techniques Work for Radioactive
Most Radioactive Contamination is on Surfaces
Removal of Outer Clothing is Very Effective
Remove Clothes and Wrap Patient in Sheets
Enforce Clean Zones and Hot Zones
INTERNAL RADIATION EXPOSURE
Radioactive Material Deposited in the Body
Pathways
Inhalation of Dust, Mists or FumesIngestion of Contaminated Food or Water
Injection Via Puncture WoundAbsorption Through Skin or Via a Wound
Internal Radiation Exposure
Internal Radiation Exposure
Rarely any method to reduce exposure once in the body•ILong physical and biological half-life, may irradiate
individual for rest of lifeEstimates of dose are complex
Metabolism
Complex biological process of elimination and concentration
High biological variability
Fraction of energy released deposited in other organs
Internal Radiation Exposure
part 2
At low doses, Radiation Injury is a Statistical Probability
In all cases, the effects of radiation injury will be delayed
Somatic and genetic effect of low level radiationstochastic and non stochastic biological effects
Primary biological effect of radiation is cancer.
Radiation Syndromes and Injury
The more frequently cells divide, the more sensitive they are to radiation injury. The more specialized the cells are, the less sensitive they
are to radiation injury.
Radiation Syndromes and Injury
Between 0 and 100 radsGenerally there is no clinically observable changes
Some nausea at the high end of range in more susceptible personsSome blood changes above 25 rads
100 - 400 radsThe hematopoietic system is affected
Blood cell precursors are very radiosensitiveGradual depression in blood count over days or weeksIncreased susceptibility to infection and hemorrhage
Most recover at lower end of range with some medical care
Acute Radiation Syndromes(VERY HIGH DOSES-Short Time Frame)
400-1400 radsGastrointestinal system is affected
Cells lining the intestinal track are radiosensitiveBacteria and toxic material gain entry into the bloodstream
Diarrhea, dehydration, infection, toxemiaSurvival is unlikely at the upper end of range
Above 1400 radsCardiovascular and Central Nervous System is affected
Blood supply is impaired leading to nausea, vomiting, convulsions,or unconsciousness. There is no hope for survival
LD 50/30 is approximately 450 rads with modest medical treatement
Acute Radiation Syndromes(continued)
Relative Risk
Relative risk of 1-in-a-million chances of dying :
• Smoking 1.4 cigarettes ( Lung cancer )
• Spending 2 days in New York City ( Air pollution )
• Driving 40 miles in a car ( Fatal crash )
• Flying 2,500 miles in a jet ( Fatal crash )
• Canoeing for 6 minutes ( Drowning )
• Receiving 40 mrem of radiation ( Cancer )
Risk Perspective
Loss of life expectancy (in days due to various causes :
• Construction worker • Driving a small car • Being an unmarried female• 25 % overweight • Coffee • Smoking one pack a day • Being an unmarried male • All industry • Radiation (100 mrem/yr -70 yrs) • Alcohol (U.S. average)
Risk Perspective
Loss of life expectancy (in days due to various causes :
• Being an unmarried male 3500 (10 years)• Smoking one pack a day 2250 ( 7 years)• Being an unmarried female 1600 ( 5 years)• 25 % overweight 777 ( 2 years)• Alcohol (U.S. average) 365 ( 1 year)• Driving a small car 290• Construction worker 227• All industry 60• Radiation (100 mrem/yr -70 yrs) 10• Coffee 6
The Dirty Bomb
• Radiological Dispersal Device (RDD)– Conventional Explosive and Radioactive Material
• Small Localized and Widely Dispersed Scenarios– Dispersal Potential Depends of Physical Form of RAM– Amount of Explosive and Local Weather Drives Dispersion
• Low Level Exposures and Contamination Likely
• Large Psychosocial Effects - Fear Factor
• To Contact NIAT During Office Hours– MA Radiation Control Program
• 617.727.9710
• Off Hours Through– MA State Police
• 508.820.2121
Nuclear Incident Advisory Team
Contact NIAT