DDOSEOSESS AND SAND SOURCESOURCES

OF RADOF RADIIATATIION ON EXPOSUREEXPOSURE

DDOSE CONCEPTS, OSE CONCEPTS,

QUANTQUANTIITTIIES AND UNES AND UNIITSTS

Radiation Radiation exposureexposure

For X and gamma rays, exposure is precisely defined in terms of the amount of ionization produced in air by

the radiation source

Radiation exposure is a measure of the intensity of the radiation field

Units of Units of exposedexposed ddoseose

The SI unitThe SI unit::

coulombs per kilogram coulombs per kilogram (C(C//kgkg))

Traditional (old) unit: Roentgen (R)

1 R = 2.58 x 10-4 coulomb/kg

Absorbed dose (D)Absorbed dose (D)

Energy imparted to matter from any type of radiation

D - absorbed dose,E - energy absorbed by material of mass ‘m’

Units of Units of aabsorbed bsorbed ddoseose

The SI unitThe SI unit::

joulejoule//kilogram orkilogram or gray (Gy)gray (Gy)

1 Gy = 1 1 Gy = 1 JJ/kg/kg

Traditional (old) unit:

rad rad ((radiationradiation absorbedabsorbed dosedose))

1 Gy=100 1 Gy=100 rradad

Variants of radiation exposureVariants of radiation exposure

Local irradiation Total irradiation

Acute irradiation

Prolonged irradiation

Chronic irradiation

Fractioned irradiation

External irradiation Internal irradiation

Equivalent dose Equivalent dose (H(HTT))

Accounts for biological effect

per unit dose

radiation weighting absorbed

factor ( WR ) dose (D)

HT = WR x D

X

Radiation weighting factorsRadiation weighting factors (W (WRR))

 

Radiation type and energy range

WR

Photons (X-rays and gamma-rays) all energies Electrons, all energies Neutrons <10 keV 10-100 keV >100 kev to 2 MeV 2-20 MeV >20 MeV Protons >20MeV Alpha-particles, fission fragments

1 1 5 10 20 10 5 5 20

Unit of Unit of equivalent equivalent dosedose

The SI unitThe SI unit:: sievert (Sv)sievert (Sv)

HHTT (Sv) (Sv) = = WWRR x x D (Gy)D (Gy)

Traditional (old) unit:

remrem (roentgen equivalent man)(roentgen equivalent man)

HHTT (rem) = (rem) = W WRR x x D (D (radrad))

1 Sv = 100 rem1 Sv = 100 rem

Effective dose (E)Effective dose (E)

Risk Risk related parameter, takingrelated parameter, taking relative relative radiosensitivityradiosensitivity of of each organ and tissue each organ and tissue intointo accountaccount

E = E = ΣΣTT (W (WTT x H x HTT))

WWT T - - ttissue weighting factor for organ Tissue weighting factor for organ T

HHTT - - equivalentequivalent dose received by organ or tissue T dose received by organ or tissue T

The SI unit of effective doseThe SI unit of effective dose:: sievert (Sv)sievert (Sv)

Tissue weighting factors (WTissue weighting factors (WTT))Organ or tissue Tissue weighting

factor (WT)

GonadsRed bone marrowColonLungStomachBladderBreastLiverOesophagusThyroidSkinBone surfaceRemainder

Total

0.20.120.120.120.120.050.050.050.050.050.010.010.05

1.0

Collective effective dose Collective effective dose ((SS))

Total radiation dose incurred by population

S = S = ΣΣii (E(Eii x N x Nii))Ei - average effective dose in the population subgroup i Ni - number of individuals in subgroup i

The SI unit of collective effective doseThe SI unit of collective effective dose:: man-sievert (man-Sv)

Conversion between units Conversion between units used in radiation protectionused in radiation protection

Physicalquantity

SI unit Non-SIunit

Relationship

Activity

Exposure

AbsorbeddoseEquivalentdose

becquerel

coulomb/kg

gray (=J/kg)

sievert

curie (Ci)

roentgen ®

rad

rem

1 Bq=2.7x10-11 Ci1 Ci=3.7x1010Bq1 mCi=37 MBq1 R=2.58x10-4 C/kg1C/kg=3876 R1 Gy=100 rad1 rad=1 cGy1 Sv=100 rem1 rem=10 mSv

Sources and Sources and llevels evels of of rradiation adiation eexposure xposure

to to ppopulationopulation

Sources of radiation exposure Sources of radiation exposure to people populationto people population

Background Background radiation radiation

• Terrestrial radioactivity

• Cosmic radiation

• Internal radioactivity

Terrestrial Terrestrial rradiationadiation::external and internal exposureexternal and internal exposure

U-238 Ra-222

Th-232 Ra-220

High background areasHigh background areas

Cosmic Cosmic rradiationadiation

Internal Internal rradioactivityadioactivity

Radioactivity

in diet• potassium-40

• lead-210

• polonium-210

Background radiationBackground radiation

Cosmic - 0.3 mSv

Food - 0.4 mSvTerrestrial - 0.3 mSv

Radon - 2 mSv

Air

Natural background radiation doses in Europe

Naturally occuring background levels of radiation can typically range from 2.0 to 4.0 mSv a year

Artificial sources Artificial sources of ionizing radiationof ionizing radiation

Radioactive sources Radioactive sources

Electric generators of ionizing radiation Electric generators of ionizing radiation

Activities using nuclear energy:Activities using nuclear energy: nuclear weapons nuclear weapons nuclear reactors nuclear reactors

Radioactive sourcesRadioactive sources

Radioactive sources are present in the sealed (normally non spreadable) and unsealed form (spreadable):

GammagraphyGammagraphy essentially uses as sources essentially uses as sources iridium-192 and sometimes cobalt-60 iridium-192 and sometimes cobalt-60

NeutrongraphyNeutrongraphy uses sources of neutrons like uses sources of neutrons like californium-252 or an americium/beryllium californium-252 or an americium/beryllium couple. couple.

BetagraphyBetagraphy uses beta sources like carbon-14. uses beta sources like carbon-14.

Chemical and biological radiation-treatmentChemical and biological radiation-treatment uses gamma radiation sources cobalt-60 or uses gamma radiation sources cobalt-60 or caesium-137. caesium-137.

Radioactive sources in medicineRadioactive sources in medicine

In medicine there are three uses In medicine there are three uses for non-sealed radioactive nuclides:for non-sealed radioactive nuclides:

Biological analyses:Biological analyses: radio-markers have been replaced radio-markers have been replaced progressively by non-radioactive markers. progressively by non-radioactive markers.

Medical imaging:Medical imaging: nuclear medicine department use nuclear medicine department use radio-pharmaceuticals for diagnostics, which are radio-pharmaceuticals for diagnostics, which are ingested by the patient to obtain an image of the ingested by the patient to obtain an image of the tissue or organ while it is functioning.tissue or organ while it is functioning.

Therapy:Therapy: radio-pharmaceuticals can constitute the radio-pharmaceuticals can constitute the treatment itself, for example iodine 131 for the treatment itself, for example iodine 131 for the treatment of thyroid cancer. treatment of thyroid cancer.

Electric generators Electric generators of ionizing radiationof ionizing radiation

The industrial applications of electric generators of ionizing radiation are neighbors of radioactive sources.

Medical applications comprise radio-diagnostics and radiotherapy:

Medical radio-diagnostics is man’s largest source of exposure to ionizing radiation. It uses standard radiography equipment and X-scanners.

The electric generators used in radiotherapy are electron accelerators of medium energy (20 million volts) which enable a beam of electrons or X-rays to be obtained.

In the research sector the large accelerators and scientific instruments are used to study the fine structure of matter.

Effective doses from mEffective doses from medical edical eexposurexposure

Effective dose (mSv)

Equivalent period of natural radiation

Radiography

Chest 0.02 3 days

Pelvis 1.0 6 months

IVP 4.6 2.5 years

Barium studies 9.0 4.5 years

CT (Chest, Abdomen)

8.0 4 years

Nuclear Medicine

Thyroid imaging 1.0 6 months

Bone imaging 3.6 1.8 years

Nuclear weaponsNuclear weapons

Nuclear weapons can function by two very different modes – nuclear fission or nuclear fusion:

Fission armsFission arms employ the principle of an employ the principle of an uncontrolled chain reaction, i.e. each fission uncontrolled chain reaction, i.e. each fission reaction leads to several further fission reactionsreaction leads to several further fission reactions

Fusion arms (thermonuclear)Fusion arms (thermonuclear) use the fact that use the fact that the union of deuterium and tritium to form a the union of deuterium and tritium to form a single nucleus of helium liberates a very large single nucleus of helium liberates a very large amount of energyamount of energy

Summary number of explosions of Summary number of explosions of nuclear weapons from 1945 to 1998nuclear weapons from 1945 to 1998

CountryCountry Years Years Number of Number of explosionsexplosions

USAUSA 19451945 –– 1992 1992 10301030

RussiaRussia 19491949 –– 19911991 716716

FranceFrance 19601960 –– 19971997 210210

Great Britain Great Britain 19501950 –– 19601960 4444

ChinaChina 11964964 –– 19961996 4545

IndiaIndia 1974, 19981974, 1998 66

PakistanPakistan 19981998 55

Summary number of nuclear Summary number of nuclear explosions in atmosphereexplosions in atmosphere

45

22 21

193

142

45,6

33,6

10,6

5,2 5

USA Russia

FranceChina Britain

%

Nuclear explosions in atmosphere Nuclear explosions in atmosphere in various yearsin various years

France

0

10

20

30

40

50

60

70

80

90

1945 1950 1955 1960 1965 1970 1975 1980

Ecological consequences of nuclear Ecological consequences of nuclear

explosions and radiation accidentexplosions and radiation accident Summary activity, Summary activity,

x 10x 101616 Bq BqContamination areas, Contamination areas,

kmkm22

Nuclear explosions in Nuclear explosions in atmospheresatmospheres

181181 060060 510510 x x 10101616

Chernobyl accident, 1986Chernobyl accident, 1986 185185 250250 x x 101066

River Techa accident, River Techa accident, 19501950

10,210,2 22 x x 101022

Kyshtym accident, 1957Kyshtym accident, 1957 7,47,4 223 x 3 x 101033

Wind scale accident, 1957Wind scale accident, 1957 1,11,1 3 x 3 x 101022

Lake Karachay accident, Lake Karachay accident, 19671967

0,0030,003 22 x x 101022

EffectiveEffective doses doses received received duringduring various various types of types of workwork

‘Non-coal’ mining16.3 milisieverts

Dos

e in

mili

siev

erts

Comparison Comparison of radiationof radiation doses doses from any sourcesfrom any sources

0.1 0.1 mSvmSv:: dental dental XX-ray or return flight across -ray or return flight across AtlanticAtlantic1 1 mSvmSv:: average yearly dose from natural average yearly dose from natural radiation excluding radon radiation excluding radon 20 20 mSvmSv:: In many countries, the highest In many countries, the highest allowable yearly dose for people working with allowable yearly dose for people working with radioactivityradioactivityA few A few 100 mSv/100 mSv/year:year: lower limit for deterministic lower limit for deterministic effects from effects from prolongedprolonged exposure exposure10001000 to few to few 1000 mSv1000 mSv:: thresholds for different thresholds for different deterministic effects at acute exposuresdeterministic effects at acute exposures10 000 10 000 mSvmSv:: will kill most people and higher will kill most people and higher animals after acute exposureanimals after acute exposure

Dose Dose llimits imits rrecomended by ICRP (1991)ecomended by ICRP (1991) wwhole hole bbodyody

Occupationalexposure

Public exposure

50 mSv maximum in any 1 year 100 mSv in 5 years

5 mSv in any 5 consecutive years

Working figure 20 mSv per year

Working figure 1 mSv per year

Dose Dose llimits imits rrecomended by ICRP (1991)ecomended by ICRP (1991) ttissuesissues

Annual doses to tissues  Occupational Public

Lens of the eye

150 mSv 15 mSv

Skin (1 cm2) 500 mSv 50 mSv

Hands and feet or individual organ

500 mSv  

Modalities of irradiation and risk of radiation exposure

Risk due to radiation exposureRisk due to radiation exposure

External exposureExternal exposure

The risks associated with external exposure depend on the type of incident radiation:Alpha radiation does not present any risk by external exposureBeta radiation can be hazard at the site of exposure on the skin and deep dermaNeutrons entail the same risks as gamma radiationGamma radiation reaches the skin, the derma and all deep tissues

The San Salvador accident The San Salvador accident in February 1989 in February 1989

Three employees at an industrial sterilization plant in Three employees at an industrial sterilization plant in San Salvador were using a very significant Co-60 source of San Salvador were using a very significant Co-60 source of 600 TBq (more than 15,000 Ci). They were seriously irradiated 600 TBq (more than 15,000 Ci). They were seriously irradiated due to obsolete plant and their not being aware of the risks. due to obsolete plant and their not being aware of the risks.

As a result of their position and the time they spent As a result of their position and the time they spent near the source, the whole body exposure doses they near the source, the whole body exposure doses they received have been estimated at 8 Gy, 4 Gy and 3 Gy, received have been estimated at 8 Gy, 4 Gy and 3 Gy, respectively. respectively.

Vomiting appeared less than two hours after Vomiting appeared less than two hours after exposure. The three victims were referred to the nearest exposure. The three victims were referred to the nearest hospital because they felt very tired and could not stop hospital because they felt very tired and could not stop vomiting. They did not present any other sign of acute vomiting. They did not present any other sign of acute exposure. Although they had mentioned their work in a plant exposure. Although they had mentioned their work in a plant using ionizing radiation, they were diagnosed as having food using ionizing radiation, they were diagnosed as having food poisoning. poisoning.

Acute irradiation syndrome was only recognized three Acute irradiation syndrome was only recognized three days later when another patient presented with erythema, days later when another patient presented with erythema, skin burns, nausea and vomiting and told them that there had skin burns, nausea and vomiting and told them that there had been a technical accident at an irradiation plant. been a technical accident at an irradiation plant.

External contaminationExternal contamination

The risks linked to external exposure of the skin differ according to the type of radiation:alpha emitting radio-elements do not a priori present any risk by external contamination, beta emitting radio-elements do present a special risk because they entail exposure which is almost exclusively of the skin, gamma emitting radio-elements pose the same problems by external contamination as in external exposure, external contamination by a neutron emitting radio-element is impossible.

External contamination reveals a secondary potential risk of internal contamination by inhalation, ingestion or breaking and penetration of the skin.

People involved in the Chernobyl accident in 1986

The Chernobyl accident, 26 April 1986, involved the very The Chernobyl accident, 26 April 1986, involved the very serious irradiation and contamination of a number of people serious irradiation and contamination of a number of people working in the power station and those who immediately working in the power station and those who immediately intervened, it provides a good example of external contamination. intervened, it provides a good example of external contamination.

More than 200 patients were hospitalized in the hours More than 200 patients were hospitalized in the hours following the catastrophe. Before this massive flood of victims, the following the catastrophe. Before this massive flood of victims, the initial efforts to manage the situation were limited to treatment of initial efforts to manage the situation were limited to treatment of the symptoms a full assessment of lesions, treatment of traumatic the symptoms a full assessment of lesions, treatment of traumatic lesions and summary external decontamination. The latter fact was lesions and summary external decontamination. The latter fact was revealed to be particularly damaging as all the patients had revealed to be particularly damaging as all the patients had external contamination by fission products, such as Cs-137, Sr-90, external contamination by fission products, such as Cs-137, Sr-90, or I-131, all of them being beta and some gamma emitters. Beta or I-131, all of them being beta and some gamma emitters. Beta emitters on the skin caused severe radiological burns with complex emitters on the skin caused severe radiological burns with complex development. development.

It is estimated that 5 of the 28 premature deaths following It is estimated that 5 of the 28 premature deaths following the accident were attributable in part to radiological burns. These 5 the accident were attributable in part to radiological burns. These 5 deaths, and perhaps others, could doubtless have been avoided if deaths, and perhaps others, could doubtless have been avoided if good external decontamination of all the exposed subjects had good external decontamination of all the exposed subjects had been carried out in the shortest time. been carried out in the shortest time.

Internal contaminationInternal contamination

When radioactive nuclides enter an organism it is still called internal exposure. Incorporation can occur via different pathways: respiratory, digestive, transcutaneous or through breaking and penetration of the skin. The most frequent points of entry are by inhalation and wounds.

In internal contamination the radio-elements are in contact with living cells. This position does not much alter the risk induced by beta or X radiation. By contrast, the risk associated with alpha radiation, which did not exist for the other modes of exposure, is major here.

The presence of radio-elements in an organism is not always pathological, a certain number of atoms, of which the organism is constructed, are radio-elements (example: K-40).

Paints for luminous watch faces

In the 1920s and 1930s the clock making industry used radium 226 and 228 in radio-luminescent paint for watches. At this time, the risk from alpha emitting radio-elements was almost unknown.

The workers who painted the luminous faces had the bad habit of tapering their brushes with their lips. Every time they did this they ingested several becquerels of radium. The fact that radium and calcium are chemical homologues, resulted in rare bone cancers appearing starting from the 20s, in the form of carcinoma of the sinus of the face.

An epidemiological enquiry demonstrated the link between exposure to radium and the risk of bone cancer in 2,403 workers, whose ingestion of quantities of radium could be evaluated. 64 were suffering from osteosarcoma whereas 2 cases of this type of cancer would have been expected statistically.

Common risksCommon risks

Approximately 1 in 10,000 will die fromApproximately 1 in 10,000 will die from– Working one year in a safe industryWorking one year in a safe industry– Receiving 50 mSv whole bodyReceiving 50 mSv whole body– Smoking 10 packs of cigarettesSmoking 10 packs of cigarettes– Living with a smoker for 15 yearsLiving with a smoker for 15 years– Drinking 50 bottles of wineDrinking 50 bottles of wine– Taking a 1,000 mile bike rideTaking a 1,000 mile bike ride– Traveling 30,000 miles by carTraveling 30,000 miles by car– 10,000 hours flying time10,000 hours flying time

Summary of lectureSummary of lecture• Becquerel (Bq), coulomb per kilogram (C/kg), gray (Gy) and sievert (Sv) are part of International System of Units (SI)• Absorbed dose of radiation in SI units is expressed in gray (Gy)• Ability of some types of radiation to cause more significant levels of biological damage taken into account with radiation weighting factor used to determine equivalent dose, expressed in sieverts (Sv) • Effective dose, expressed in sieverts (Sv), is based upon the estimates of the relative risk of stochastic effects from the irradiation of the different tissues

• Natural sources of radiation is made 85 % of effective doses received people from various sources of radiation

Lecture is endedLecture is ended

THANKS FOR ATTENTION

In lecture materials of the International Atomic Energy Agency (IAEA), kindly given by doctor Elena Buglova, were used