External and Internal Radiation Dose

24
1 Semmelweis University Faculty of Dentistry, Budapest Studium: Radiation Protection/Strahlenschutz, 2011/2012 PUBLIC EXPOSURES (Strahlendosen für die Bevölkerung) 26. October, 2011, 16:00- 17:10 Room: Árkövy

description

Semmelweis University Faculty of Dentistry, Budapest Studium: Radiation Protection/Strahlenschutz, 2011/2012 PUBLIC EXPOSURES (Strahlendosen für die Bevölkerung) 26 . October, 2011 , 16:00-17:10 Room: Árkövy Béla Kanyár hab. PhD, Semmelweis Univ., Radiation Protection Service. - PowerPoint PPT Presentation

Transcript of External and Internal Radiation Dose

Page 1: External and Internal Radiation Dose

1

Semmelweis University Faculty of Dentistry, Budapest

Studium: Radiation Protection/Strahlenschutz, 2011/2012

PUBLIC EXPOSURES (Strahlendosen für die

Bevölkerung)26. October, 2011, 16:00-17:10

Room: Árkövy

Béla Kanyár hab. PhD, Semmelweis Univ., Radiation Protection Service

Page 2: External and Internal Radiation Dose

2

External and Internal Radiation Dose

Committed dose: ∫ D(t) dtτ

0

According to regulation: τ = 50 y (adults), 70 y (children)

external internal (by intake of radioisotopes)

τ time˚

Dose rate

Page 3: External and Internal Radiation Dose

3

Categories of Exposures(with respect to the regulation)

• Occupational exposures (Berufliche …)

• Public (incl.: Medical?) exposures

• (Non-human Biota exposures ?)

Page 4: External and Internal Radiation Dose

4

Sources of Public Exposures

• Natural Exposure (Natürliche…)annual impact: 2.5 mSv effective

dose (external + internal)

• Artificial Exposure (Künstliche …)annual impact: 1.7 mSv effective

dose (mainly due to medical, X-ray diagnostics)

Page 5: External and Internal Radiation Dose

5

Natural: Cosmogene and terrestrial radionuclides Univerzum (ions, α-, β-, n-, müon- … radiation)

γn

γ

Atmosphere

Earth Surface

Raindr.

Page 6: External and Internal Radiation Dose

6

Page 7: External and Internal Radiation Dose

7

Terrestrial exposure: natural radioactive decay series (r. nuclides mainly in soil)

Pb-208stabile

Rn-22032 s

Th-232T=14 mrd y

. . . . . .

U-235T=0.72 mrd y

Actinium serie

Uranium serie

Thorium serie

Rn-2193,9 s

Pb-207stabile

U-238T=4.5 mrd y

Rn-2223,8 day

Pb-206stabile

. . .

. . .

. . .

. . .

Main processes: Rn-emanation: deliberation of Rn molecules from chem.-phys.binding in solid phase

of soil (to gas form in soil)

Rn-exhalation: outflow of Rn gas from soil to atmosphere.

Page 8: External and Internal Radiation Dose

8

Rn-222 concentrations indoor and outdoorIn winter: due to small ventilation, the Rn-gas accumulates indoor

Living room (indoor)

100-500 Bq/m3

soil

Rn-222 (noble gas)

Outdoor, air:

5-10 Bq/m3, to height of nearly 200-300 m

exhalation

ventilation

500-2000 Bq/m3 Rn-222

Ra-226 Rn-222

„cultural man”: 80 % indoor

α

Page 9: External and Internal Radiation Dose

9

Rn-conc. due to periodic ventilation, for short (minutes) time intervals

• CRn (Bq/m3)

300

200

100

Short and periodic ventilations, 5-6 hourly

6 h 9 h 12 h 15 h 18 h

Page 10: External and Internal Radiation Dose

10

Artificial exposures

• The main sources of the impact are: • - contamination of air, soil, vegetation etc.

in the close environment of: nuclear power plants (NPP) and isotope labs, due to discharges of radionuclides

• - contamination of spring waters in the close environment of Radioactive Repositories

• Medical patient: X-ray diagnostic tests,…

Page 11: External and Internal Radiation Dose

11

irrigationSource

Atmosph

Surface water

Soil

Vegetables

Feeding vegetation

Animals, anim. prod.

water plants, fishes

Man

Sediment

inhalation

•A radioaktív anyag migrációja a bioszférában és besugárzási útvonalak az ember esetén (szaggatott nyíl a sugárzás, folyamatos nyíl a radioaktív anyag terjedését jelöli)

Transport, migration of radionuclides discharged from NPP/isotope lab. Exposure pathways (Expositionspfaden).

external expos.

external expos.

intakes

intakes

Page 12: External and Internal Radiation Dose

12

Atmospheric dispersion near to the source

• In „normal practice”, 2-3 km far from the NPP no contamination are detected, only assessments are provided from the discharges and meteorological parameters (fequently used: Gaussian plume model)

Page 13: External and Internal Radiation Dose

13

Averaged dose levels, inc. confidence ranges (natural sources)

Sources, pathways Mean values and ranges (mSv)

Cosmic rays, external, annual effective dose 0.38 (0.3-1.0)

Inhalation and ingestion of cosmogene radionuclides (internal, committed effective dose, annual)

0.012 (0.008– 0.02)

Terrestrial, external, annual effective dose, outdoor

, indoor

0.45 (0.3-0.6)

0.55 (0.4-0.8)

Terrestrial, annual internal, committed eff. dose (without Rn and daughters)

0.27 (0.2-0.5)

Terrestrial, annual internal, comitted eff. Dose from the Rn daughters 1.2 (0.5-5.0)

Terrestrial, annual internal, committed equivalent dose to lung, due to Rn daughters

10

Technical Enhanced Natural Occurring Radioactive Material (TE-NORM): indoor (building material: Ra-226 content), …

Page 14: External and Internal Radiation Dose

14

Averaged individual doses to public (artificial sources)

Sources, components Mean and range (mSv)

Medical, external (mainly X-ray diagn),annual effective dose 1.5 (0.1-5)

From NPP (1-5 km far), annual 0.01 ( - 0.1)

Atomic bombs (Hirosima, Nagaszaki, inside the city area) 100-5000

Nuclear tests, North hemisphere 0.1-2

, South < 0.01

Chernobyl accident, effective dose

within r ≈ 30 km circle 1-20

Central and West Europe 0.1-2

North America 0.01

Japan 0.01

South hemisphere < 0.01SE X-ray stations, eff. dose by films (-2009, last 3 years): ≈ 0.5 mSv / ySE dentist X-ray stations (last 3 years): < 0.3 mSv / ySE nuclear medic. labs (last 3 years): ≈ 0.7 mSv / év

Page 15: External and Internal Radiation Dose

15

Medical exposure (patient dose per test)

0

2

4

6

8

10

12

14

16

18

20

Végtag

ok

Mell

kas f

elv.

Mam

mog

ráfia

Epeviz

sg.

Hasi C

T

Mell

kas-C

T

Érfesté

s

Inter

venc

pajzs

m (Tc-

99m)

máj-lép

-szc.(

Tc-99

m)

vese

-szc.

(Tc-9

9m)

mammo-

szc.(

Tc-99m

)

szívi

zompe

rf. (T

c-99m

)

daga

nat (

PET)

szívi

zompe

rf.(T

l-201

)

E [

mS

v]

Page 16: External and Internal Radiation Dose

16

Hírsugár (2007. júliusi száma), Sugárhumor/Déri Zsolt(Eötvös Loránd Fizikai Társulat Sugárvédelmi Szakcsoport)

Page 17: External and Internal Radiation Dose

17

• External dose: nearly 100 % in medical, dental praxis - X-ray diagn., Radiation therapy - Meassurement of X-rays (≈ 60 keV 20-150 keV): mainly by ionization chamber (energy dependency)

• Internal dose: Radioactive isotopes: used as tracers to test the metabolic

systems (nuclear medicine), and in internal radioisotope therapy (I-131 to thyroid)Dose assessment: Calculation from measured radionuclide concentration of air and food samples (inhalation and ingestion dose).

- α-, β- and γ-ray contamination of whole body, surfaces, samples etc.: special sample processing, detectors: NaI(Tl), semiconducter ones (Ge, Si)

Determination of exposures

Page 18: External and Internal Radiation Dose

18„Rainpeaks”: due to intensive wash out to the surface, from atmosphere

Environmental monitoring, early warning system Continously (mainly by 2-10 minutes frequency) measured dose rates, usually 1 m heigh from the surface

Page 19: External and Internal Radiation Dose

19

Personel monitoring, dose meters

Page 20: External and Internal Radiation Dose

20

Whole body counter, determination incorporated radionuclides (geometries used)

Ív geometria

Szék geometria

Álló geometria (mozgó, vagy rögzített detektor)

Fekvő scanning geometria Fekvő ágy geometria

detector

Page 21: External and Internal Radiation Dose

21

Scanning whole body counter with two detectors (Pb etc shielding to minimize the

effect of outside background)

Page 22: External and Internal Radiation Dose

22

A Cs-137 in the inhabitans of capital Budapest (measured by: Andrási, A., …(KFKI))

Atmospheric nuclear tests (SU-USA: 1945-1964), later on by less intensity: Fr, GrB, China,…)

Activ./body weight

Page 23: External and Internal Radiation Dose

23

90Sr contamination (pure β-emitter, sample measurements)

Sr-90 activities in teeth, in capital Budapest(Turai I.: Sugáreg. ismeretek, 1993)

0

20

40

60

80

100

120

140

1955 1960 1965 1970 1975 1980

év

mB

q/g

Ca Milky

tooth

Permanent tooth

Page 24: External and Internal Radiation Dose

24

Literature:Basic safety standards. IAEA Safety Series No. 115, Vienna, 1996)Kanyár, B., G. J. Köteles: Dosimetry and Biological Effects of Ionizing Radiation, Chapter 10, in: Vértes, A., Z. Klencsar (eds): Handbook of Nuclear Chemistry, Springer, 2010 UNSCEAR Reports (2-4 yearly, UN NewYork, …)

EU Radiation Protection No. 136, 2004. European guidelines on radiation protection in dental radiologyICRP (Intern. Comm. on Radiol. Prot.) Public. No 103, Pergamon P., NewYork, London, 2007.