Semmelweis University Faculty of Dentistry, Budapest
Studium: Radiation Protection/Strahlenschutz,
2015/2016
PUBLIC EXPOSURES
(Strahlendosen für die Bevölkerung)
Gabriella Taba,
Semmelweis Univ., Radiation Protection Service
2.November, 2015, Balogh Károly terem, 1088 Budapest, Szentkirályi u. 47
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External and Internal Radiation Dose
Radiation Units:
Exposure (CLINICAL)
Absorbed Dose (CLINICAL)
Equivalent Dose (RADIATION PROTECTION)
Effective Dose (RADIATION PROTECTION)
Dose rate
τ
Committed dose: ∫
0
˚
D(t) dt
According to regulation: τ = 50 y (adults), 70 y (children)
τ time
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http://www.cfact.org/2014/01/07/true-facts-about-ocean-radiation-and-the-fukushima-disaster/
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Categories of Exposures
(with respect to the regulation)
• Occupational exposures (Berufliche …)
• Public (incl.: Medical?) exposures
• (Non-human Biota exposures ?)
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https://www.clpgroup.com/NuclearEnergy/Eng/images/science/3_2_1a.jpg
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)
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NCRP Report 160: Ionizing Radiation Exposure of
the Population of the United States
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Natural: Cosmogene and terrestrial radionuclides
Univerzum (ions, α-, β-, n-, müon- … radiation)
Atmosphere
n
γ
Raindr.
Earth Surface
γ
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Areas of high natural background
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Cosmogenic isotopes are created when elements in
the atmosphere or earth by high energy particles.
9,400 years of cosmic radiation and solar activity from ice cores and tree rings Friedhelm Steinhilbera,1, Jose A. Abreua2, Jürg
Beera , Irene Brunnera , Marcus Christlb , Hubertus Fischerc , Ulla Heikkiläd , Peter W. Kubikb , Mathias Manna , Ken G.
McCrackene , Heinrich Millerf , Hiroko Miyaharag , Hans Oerterf , and Frank Wilhelmsf
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Terrestrial exposure: natural radioactive decay
series (r. nuclides mainly in soil)
Thorium serie
Th-232
T=14 mrd y
...
Rn-220
...
Rn-219
...
Rn-222
32 s
...
Pb-208
stabile
...
Pb-207
stabile
...
Pb-206
stabile
Actinium serie
U-235
T=0.72 mrd y
3,9 s
Uranium serie
U-238
T=4.5 mrd y
3,8 day
Main processes:
Rn-emanation: deliberation of Rn molecules from chem.-phys.binding in solid phase
of soil (to gas form in soil)
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Rn-exhalation: outflow of Rn gas from soil to atmosphere.
Rn-222 concentrations indoor and outdoor
In winter: due to small ventilation, the Rn-gas accumulates indoor
„cultural man”: 80 % indoor
Living room
(indoor)
Outdoor, air:
Bq/m3
100-500
Rn-222 (noble gas)
ventilation
5-10 Bq/m3, to
height of nearly
200-300 m
Ra-226 α Rn-222
exhalation
soil
500-2000 Bq/m3 Rn-222
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Rn-conc. due to periodic ventilation, for short
(minutes) time intervals
• CRn (Bq/m3)
Short and periodic ventilations, 5-6 hourly
300
200
100
6h
9h
12 h
15 h
18 h
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Radon in the house and protection
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http://mr-radon.ca/wordpress/wp-content/uploads/2014/01/howRadonEntersHouse.png
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
• Nuclear weapons tests
• Naturally Occurring Radioactive Material
• Medical patient: X-ray diagnostic tests,therapy
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https://en.wikipedia.org/wiki/Nuclear_weapons_testing#/media/File:Worldwide_nuclear_testing.svg
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Sr-90 activity concentration in teeth and milk teeth
year
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Transport, migration of radionuclides discharged from
NPP/isotope lab. Exposure pathways (Expositionspfaden)
external expos.
inhalation
Vegetables
Atmosph
Source
Soil
intakes
Feeding
vegetation
irrigation
Surface
water
Sediment
Man
Animals,
anim. prod.
intakes
water plants,
fishes
external expos.
•A radioaktív anyag migrációja a bioszférában és besugárzási útvonalak az ember
esetén (szaggatott nyíl a sugárzás, folyamatos nyíl a radioaktív anyag terjedését jelöli)
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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,
0.012 (0.008– 0.02)
committed effective dose, annual)
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
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Technical Enhanced Natural Occurring Radioactive Material (TENORM): indoor (building material: Ra-226 content)
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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
< 0.01
SE X-ray stations, eff. dose by films (-2009, last 3 years): ≈ 0.5 mSv / y
SE dentist X-ray stations (last 3 years):
< 0.3 mSv / y
SE nuclear medic. labs (last 3 years):
≈ 0.7 mSv / év
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Heart perfusion scintigraphy
Tumor scintigraphy
Heart perfusion scintigraphy
Mammo-scintigraphy
Kidney scintigraphy
Lkiver spleen scintigraphy
Thyroid diagnostic
Intervention
Angiography
Chest CT
Abdomen CT
Bile test
Mammography
Chest
Limb
Medical exposure (patient dose per test)
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Determination of exposures
• 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)
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Personel monitoring, dosimeter
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Whole body counter, determination incorporated
radionuclides (geometries used)
detector
Ív geometria
Szék geometria
Álló geometria
(mozgó, vagy rögzített detektor)
Fekvő scanning geometria
Fekvő ágy geometria
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NaI scintillation kit and dose rate meters
700MBq Tc-99m,
bone scint.gh.patient
1m from body
9,97mikro Sv/h
On surface the body
92mikor Sv/h
9,97mikorSv/h dose rate
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A Cs-137 in the inhabitants 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
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Environmental monitoring, early warning system
Continously (mainly by 2-10 minutes frequency) measured dose rates,
usually 1 m heigh from the surface
„Rainpeaks”: due to intensive wash out to the surface, from atmosphere,
and some patient (bone scint.grp.Tc-99m) go nearly to the detector
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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 radiology
ICRP (Intern. Comm. on Radiol. Prot.) Public. No 103, Pergamon P.,
NewYork, London, 2007.
IAEA Tech.Doc
Dr. Kanyár Béla presentation 2004-2013
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