Radiation safety principles

1. RadiationSafetyPrinciples
BY
Mr.S.DINESH.,BSCRADIOLOGY

2. Outlines
- Introduction to Radiation
- Unitsof Activity
- Alpha,Beta, Gamma Radiation
- Definitions
- Background Radiation
- Doselimits
- ALARA
- Radiation safety equipment
- Summary

3. Introduction to radiation
Radiation: is energy in the form of moving particles or
electromagnetic waves.
Thereare two typesof radiation:
- Non-ionizing radiation:does not have enough energy
to remove an electron from the atom or molecule.
Microwave, radiowave,…
- Ionizing radiation: Radiation with
enough energy to remove an electron
or more from the atom or molecule,
producing ions.
Alphaparticles,Betaparticles,gamma-rays, X-rays

5. Radioactivity
• The process by which unstable atoms
spontaneously transform into new
atoms and emit radiation
during theprocess.

6. Isotope & Radioisotope
• Isotopes: Atoms of the same element, that
contain the same number of protons, but
different number of neutrons.
• Radioisotope: unstable isotope of an element
that has radioactivity: undergoes spontaneous
decay,emitting radiation.
Radiation Safety Officer: OsamaTaqatqa

7. Units of Activity
•
Henri Becquerel,FrenchPhysicist (1852-1908)
Marie Curie,PolishPhysicist(1867–1934)
Curie(Ci):3.7X1010disintegration per
second.
• Becquerel(Bq): 1 disintegration persecond.
1mCi=37MBq

8. Half-Life
requiredThe time
for the activity to
reach one half of its
original value.

9. AlphaRadiation
• Helium Nucleus.
• Most massivetype of radiation.
• Alpha particles have a relatively
large electric charge, thus a very
strong interaction with matter.
Because of this they have a short
range.
• Hazardous only via ingestion or inhalation of alpha emitters
(Internal Hazard).

10. BetaRadiation
Positivelychargedbeta particles
(Positrons)
• Annihilation of radiation: The
interaction beta particle
and the from the
surrounding
between
electrons
atoms, producing 2
gammarays.
Negativelychargedbeta particles
(Electrons)
There are 2 main mechanisms
of interaction:
1- Ionization: The interaction
between the beta particle and the
orbital electrons of surrounding
atoms.
2- Bremsstrahlung
• Externalhazardto skinand eyes.

12. e
-
e
-
X-ray
Bremsstrahlung: Bremsen-Strahlung
- Conservationof Energy:Someof the kinetic energyof the movingelectron isconverted
into aphoton.
bremsen "to brake" andStrahlung"radiation
- Bremsstrahlungiscausedbythe deflectionof high-energyelectron bythe electric
field of anatomicnucleus.
K1
K2
K1-K2=hv

13. Gammaraysand X-rays
- External hazardto deep organsand tissues.
- Photons
- No charge
- No mass
- Highly Penetrating

15. Definitions (1)
• Exposure (R): Amount of charge
produced per unit mass of air
from ionizedradiation.
(1905–1965) British Physicist
• Absorbed Dose (Gy): Amount of
energy deposited per unit mass of
material (J/kg).
Wilhelm Röntgen (1845–1923) German
Physicist
1 Gy=100rad
1 R=2.58X10-4 C/kg

16. Definitions (2)
• DoseEquivalent (Sv):
Thequantity DE(J/kg) is used to describe the human
health risk due to the exposure to radiation.
Forexample:
For equal absorbed doses, alpha
particles could be 20 times more
damaging than betaparticles.
Rolf Sievert (1896–1966) SwedishMedicalPhysicist
1 Sv=100 remDE=DX WR
D:Absorbeddose
WR:RadiationWeighting Factor

17. EffectiveDose (Sv):
Takingrelative Radiosensitivity of each organ and
tissue.
Definitions (3)
E=DEXWT
DE:Dose Equivalent
WT: TissueWeighting Factor

19. Organor tissue Tissueweighting
factor (WT)
Gonads
Redbonemarrow
Colon
Lung
Stomac
h
Bladder
Breast
Liver
Oesophag
us Thyroid
Skin
Bonesurface
Remainder
Total
0.2
0.12
0.12
0.12
0.12
0.05
0.05
0.05
0.05
0.05
0.01
0.01
0.05
1.0

20. Source ofexposure
Annual effective dose (mSv)
Average
Cosmicradiation
Directly ionizing and photon
component
0.28
Neutron component 0.10
Cosmogenic* radionuclides 0.01
Totalcosmicandcosmogenic 0.39
Externalterrestrial radiation
Outdoors 0.07
Indoors 0.41
Totalexternal terrestrial radiation 0.48
Inhalation
Uraniumandthorium series 0.006
Radon (Rn-222) 1.15
Thoron (Rn-220) 0.1
Totalinhalation exposure 1.26
Ingestion
K-40 0.17
Uraniumandthorium series 0.12
Totalingestion exposure 0.29
Total 2.4
Background radiation
* Cosmogenic:rare isotope createdwhenahigh-energycosmic-rayinteractswiththe nucleus.

21. Food Radioactivelevels (Bq/kg)
Dailyintake
(g/d)
Ra-226 Th-228 Pb-210 K-40
Rice 150 0.126 0.267 0.133 62.4
Wheat 270 0.296 0.270 0.133 142.2
Pulses 60 0.233 0.093 0.115 397.0
Other
Vegetable
s
70 0.126 0.167 -- 135.2
Leafy
Vegetable
s
15 0.267 0.326 -- 89.1
Milk 90 -- -- -- 38.1
Composit
e Diet
1370 0.067 0.089 0.063 65.0
Radioactive levels (Intake)

23. ToUSA=5µSv/h X14 h=70 µSv

24. Recommended dose limits
Application Occupational Public
Effectivedose 20 mSvperyear 1 mSvin ayear
the lensof the eye 150mSv
the skin 500mSv
the handsand feet 500mSv
20 mSv
Investigation Levels:
- Quarterly Investigation Levels(3 months)
Basedon 2.5 %of any applicable occupationallimit.
- Annual Investigation Levels( 12 months)
Basedon 10 %of any applicable occupational limit.
Radiation SafetyOfficer: OsamaTaqatqa

25. Basicprinciples of radiation protection
Optimization
ofProtection
Individualdose
limits
Justification
of Practice

26. ALARA
AsLowAsReasonablyAchievable
EachIndividual is responsible for ensuring that his or
her exposures are kept “ALARA”.
HOW
ReduceTIMEin radiological area
IncreaseDISTANCEto radioactivematerial
Useasuitable SHIELDbetween you and sources of radiation

27. Threebasicfactorsfor protection
Useasuitable SHIELDbetween you and sources of radiation

28. BetaSource
plastic Lead
Theintensity of Bremsstrahlungx-raysincreaseswith increasing
atomic number of absorber.
Bremsstrahlung x-ray

29. Gammaor x-ray
Lead
Because of its high density, and large
number or electrons, LEADis a very good
medium for scattering x-rays and
gamma-rays.

30. - The most effective shielding materials are
hydrocarbons, e.g. polyethylene, paraffin wax ,
or water.
- Light atoms slow down the neutrons by elastic
scattering, sothat they canthen beabsorbed.
Suitable Shieldof Neutron Source

31. TotalDose=Exposurerate X Time
10mGy/h
1hour
2hour
=10mGy/h X 1 h =10mGy
=10mGy/h X 2 h =20mGy
ReduceTIMEin radiological area

32. 40mSv
50 cm
150cm
????mSv
E1X(d1)2 =E2X(d2)2
40 X(50)2 =E2X(150)2
E2= 4.4 mSv
IncreaseDISTANCEto radioactivematerial
E2=E1X(d1)2
(d2)2

33. Radiation SafetyEquipment
(Personal Monitoring)

35. Radiation safety equipment
(Workplace Monitoring)

36. Signage
RadiationWarningSign

37. Summary
-RadiationWorkers& NEstudentsare required to reviewand
understandIAEASafety Standards.
- Youshouldkeepyour exposures“ALARA”.
-Tounderstandthe basicsof safety, you
mustknowhow to useUNITS.
- Alwaysuseradiation safety equipment,
andcomplywith the approveddoselimits.
- AlwaysmakeSAFETYyour No.1 onthe list.
- Beready for training in fall,2014.

38. Thankyoufor yourverykind
attention
http://www.safetypostershop.com/
Radiation Safety Officer: OsamaTaqatqa