2. Sources of Radiation
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Elements such as thorium, uranium, radium, RN-222,
and K-40 are naturally occurring radioactive elements
that can be found in our everyday lives.
These elements can be found in:
– rocks, soil and building materials
– food and water
Some sources are a result of ground nuclear testing,
which is not naturally occurring.
3. Cosmic and Atmospheric
Radiation
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Cosmic and atmospheric radiation originates from
the sun and stars.
Earth’s atmosphere is very effective in shielding
cosmic radiation, but variations in the density of the
atmosphere can result in uneven distribution of
protection.
4. Additional Sources of Radiation
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Our bodies contain naturally occurring radioactive
elements, such as potassium.
Some consumer products, such as luminous dial
watches and smoke detectors, contain small amounts of
radioactive material.
5. Cosmic radiation can be accumulated through
one cross-country airplane trip.
Tobacco leaves absorb naturally occurring
radioactive materials from the soil and fertilizers
used to grow them.
Hospitalized individuals who undergo medical
procedures are exposed to sources of ionizing
radiation.
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6. Annual Dose from
Background Radiation
Total US average dose equivalent = 360 mrem/year
Total exposure Man-made sources
Internal 11%
Cosmic 8% Terrestrial 6%
Man-Made 18%
Radon 55.0%
Medical X-Rays
Nuclear
Medicine 4%
Consumer
Products 3%
Other 1%
11%
7. Ionizing radiation is produced by the natural decay of
radioactive material.
Beta, gamma, and x-rays are forms of ionizing
radiation that are often used in research.
Ionizing Radiation
Beta, gamma, x-rays
remove electrons
from atoms
(Ionization).
Ions are created,
which are more
chemically
reactive than
neutral atoms.
Ions can form
compounds that might
interfere with cell
division and metabolism
or cause chemical
changes in tissue.
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8. X-Rays & Gamma Rays
X-rays and gamma rays make up part of the
electromagnetic spectrum.
They can travel forever until they hit an object and
one of three reactions occurs:
Absorption
Transmission Scattering
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9. Penetrating Radiation
-X-Rays & Gamma Rays-
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X-rays and gamma rays can penetrate the body and
irradiate internal organs.
Exposure can result in external and internal doses.
Internal exposure can occur when rays are ingested,
inhaled, or absorbed through the skin.
10. Beta Particles
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Beta particles are excess electrons.
Particles can be low or high energy emitters.
Low energy emitters can be shielded by cardboard.
High energy emitters need a more dense shielding
material, such as Plexiglas.
11. Non-Penetrating Radiation
-Beta Particles-
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Can not penetrate the body to irradiate internal
organs.
Can penetrate dead outer-layer of skin and result in
damage to live skin cells.
Can cause damage to eye lenses.
Ingestion, inhalation, or absorption through the skin
might result in internal exposure.
12. Radiation Absorbed Dose
-RAD-
RAD is a unit of measurement used to describe the
amount of energy transferred from a source of ionizing
radiation to any material, including human tissue.
It is the quantity of radiation received by a patient.
As a unit of exposure, 1rad means that each gram of air at 0° C and
1atmosphere has absorbed 100 ergs of energy.
As a unit of dose, 1rad means that each gram of exposed tissue has
abosorbed 100 ergs of energy.
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13. Radiation Equivalent Man
-REM-
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Different types of ionizing radiation cause differing
degrees of biological effects even when the same level of
energy is transferred (same number of ergs).
Rem is used to express the quantity of radiation received
by radiation workers and populations.
The rate at which an individual is exposed also
influences the level of biological harm.
Dosimeter are used to measure a dose equivalent.
14. Biological Effects of radiation
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Exposure above permissible levels may result in:
Somatic Effects
Physical effects
May be immediate or delayed
Genetic Effects
Birth defects due to irradiation to reproductive
cells before conception
Teratogenic Effects
Cancer or congenital malformation due to
radiation exposure to fetus in utero
15. Biological Effects
-Threshold-
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Threshold effects might occur if an individual receives
a dose above the threshold level.
Acute Radiation Syndrome: large whole body dose in a short time
Effects occurat 100 rad
Radiation-induced cataract formation
Acute effects occur at 200 rad
Chronic effects occur at 800 rad
Other thresholds
Severe skin injury occurs at 1,500 rad
Teratogenic effects occur at 20 rad
16. Biological Effects
-Non-threshold-
Genetic effects
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Non-threshold effects might occur from any amount
of exposure to radiation.
Chance of effect occurrence is proportional to the received dose.
Severity of effects are not necessarily related to exposure level.
Chance effects include:
Cancer - estimated to be 5 deaths per 10,000 persons, whom each
received 1,000 mrem
17. Summary of Biological
Effects of Radiation
Radiation may…
• Deposit Energy in Body
• Cause DNA Damage
• Create Ionizations in Body
• Leading to Free Radicals Which
may lead to biological damage
18. Radiation Effects on Cells
Radiosensitivity Theory of Bergonie &
Tribondeau (1906).
Stem cells are radiosensitive, mature cells are
radioresistant.
Younger tissues are radiosensitive.
Tissues with high metabolic activity are
radiosensitive.
Ahigh proliferation rate and a high growth rate
result in increased radiosensitivity.
19. Response to radiation depends
on:
Total dose
Dose rate
Radiation quality
Stage of development at the time of
exposure
20. Whole Body Effects
Acute or Nonstochastic
• Occur when the radiation dose is large enough to
cause extensive biological damage to cells so that
large numbers of cells die off.
• Evident hours to a few months after exposure (Early)
• Skin burns
21. Late or Stochastic (Delayed)
• Exhibit themselves over years after acute exposure.
• Radiation induced cancers
• Leukemia
• Genetic effects
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24. When working with radioactive
material, remember to minimize your
exposure at all possible times.
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Minimize Exposure
25. Measure Your Radiation Dose
-Dosimeters-
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Use to measure the occupational dose equivalent from x-ray,
gamma, and high energy beta emitters. Dosimeters cannot
detect radiation from low energy beta emitters.
Luxel Ring Dosimeter Fetal Dosimeter
Measures… Whole body exposure Extremity exposure Exposure to a fetus
Is worn… On the torso or area of
highest likely exposure
On either hand under
the
gloves with the name
facing the radiation
source
At the waist line
Can detect… X-rays & gamma rays:
1 – 1,000,000 mrem
X-rays & gamma rays:
30 – 1,000,000 mrem
High energy beta
emitters:
High energy beta
emitters:
26. Maximum Permissible
Dose Limits (MPD)
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State and Federal regulations set maximum
permissible yearly radiation dose (MPD) limits for
adults.
Exposure up to dose limits is not expected to cause
adverse health effects.
ADULT MAXIMUM PERMISSIBLE DOSES
Whole Body – head, neck, torso, upper arms and
legs
5,000 mrem
Lens of the eye 15,000 mrem
Extremities, skin, and internal organs 50,000 mrem
Declared pregnant woman 500 mrem
27. As Low As Reasonably
Achievable (ALARA)
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Always practice ALARA
AS LOWAS REASONABLYACHIEVABLE
28. Why Practice ALARA?
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Any type of ionizing radiation poses some risk. As
exposure increases, so does risk.
Research shows that some people’s DNA is more
resistant orsusceptible to damage, and some people
have an increased risk of cancer after exposure to
ionizing radiation.
Limit your exposure whenever possible.
30. Doubling the distance from the source can reduce
your exposure intensity by 25%.
Use forceps, tongs, and trays to increase your
distance from the radiation source.
Move the item being worked on away from the
radiation area if possible.
Know the radiation intensity where you perform
most of your work, and move to lower dose areas
during work delays.
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Three Effective Strategies
-Distance-
31. Position shielding between yourself and the source of
radiation at all permissible times. Take advantage of
permanent shielding (i.e. equipment or existing
structures).
Select appropriate shielding material during the
planning stages of the experiment/procedure.
Plexiglas, plywood and lead are effective in shielding
radiation exposure. Use the proper shielding for the
type of radioactive material present.
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Three Effective Strategies
-Shielding-
32. Shielding X-Rays & Gamma Rays
Lead shielding will reduce the intensity of x-rays
and gamma rays being emitted from a source of
radiation.
To reduce exposure by a certain desired percent,
lead shielding must be a certain thickness for each
type of emitter.
Remember:
Lead shielding does not reduce exposure by 100%.
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35. Personal Protective Equipment
Fig 3. Overshoes
Often worn routinely in the
Radiopharmacy for sterility reasons.
Not always otherwise worn routinely
to prevent the spread of
contamination, but widely used for
this purpose following a spillage.
37. Radiation Safety
-Laboratory Rules-
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1. Smoking, eating, and drinking are not permitted in
radionuclide laboratories.
2. Food and food containers are not permitted in the
laboratory.
3.Radionuclide work areas shall be clearly designated
and should be isolated from the rest of the laboratory.
4. All work surfaces shall be covered with absorbent
paper which should be changed regularly to prevent
the buildup of contamination.
38. Radiation Safety
-Laboratory Rules-
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5. Protective clothing shall be worn when working with
radioactive materials. This includes laboratory coats,
gloves, and safety glasses.
6. Dosimeters shall be worn when working with
relatively large quantities of radionuclides which
emit penetrating radiation.
39. 7. All containers of radioactive materials and items
suspected or known to be contaminated shall be
properly labeled with tape or tagged with the
radiation logo and the word “RADIOACTIVE”.
8. All contaminated waste items shall be placed in a
container specifically designed for radioactive
waste.
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Radiation Safety
-Laboratory Rules-
40. Warning Labels
Mark all items used to manipulate or store
radioactive material.
CAUTION:
Radioactive
Material
Label all contaminated items.
Remove all radiation labels
and warnings on containers
that no longer contain
radioactive material and are
not contaminated.
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41. MUST be clearly visible, durable, and MUST state:
“CAUTION: RADIOACTIVE MATERIAL”
Warning Label Requirements
Labels must provide sufficient information on the
container to minimize exposure and to make sure all
proper precautions have been taken.
Radionuclide(s)
Estimated activity
Date
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42. Radioactive Waste Disposal
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Radioactive waste includes anything that contains or
is contaminated with radioactive material.
Collect radioactive waste in proper containers.
Keep containers closed and secured unless you are
adding waste.
Report the proper information on the radioactive waste
tag when material is put in the waste container.
Keep a tag on the waste container at all times.
