Radiation Safety Training

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Radiation Safety Training
ICN Dosimetry Service

• Understanding and Working Safely with Radiation

Tosh Ushino, CHP Radiation Safety Officer
Revision 0, April 2000
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What is radiation and what does it mean to me?
Or, are bananas radioactive and is that why King
Kong got to be that big?

• Did it exist before the bomb?
• Will I get cancer from it?
• How can I ensure my safety?

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There is so much misinformation about radiation

• We learned about radiation and its effects
  watching
• Sci Fi movies and TV shows
• Incredible Hulk, mutation caused by radiation
• Spiderman, bitten by a radioactive spider
• Godzilla, mutated from a weapon test
• Teenage Mutant Ninja Turtles, from radioactive
  waste
• and many others
• Unfortunately, lots of people think this is all
  true.
• and of course, Mr. Spock of Star Trek, after all
  his exciting adventures across the universe, died
  of radiation exposure

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Where does Radiation come from?

• Atoms are composed of particles
• Nucleus
• protons with positive () charge
• neutrons with no charge
• Outer shell
• electrons with negative (-) charge

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Where does Radiation come from? (contd)

• Neutrons act like to glue to hold nucleus
  together
• Protons dont want to stay together
• There are about equal numbers of protons and
  neutrons in nucleus
• If the numbers are out of balance, then the
  nucleus is unstable

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Where does Radiation come from? (contd)

• Number of protons in nucleus determines what kind
  of element the atom is
• Number of neutrons in the nucleus determines the
  isotope of that element

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Where does Radiation come from? (contd)

• Example
• Stable Hydrogen
• Nucleus composed of one proton (normal hydrogen)
• Nucleus composed of one proton and one neutron
  (deuterium)
• Unstable Hydrogen (radioactive)
• Nucleus composed of one proton and two neutrons
  (tritium)

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Where does Radiation come from? (contd)

• Example (contd)
• In a process called radioactive decay, unstable
  nucleus eventually becomes stable by ejecting
• excess particles
• excess energy
• Radiation is the ejected excess energy or
  particle
• Activity is the measure how much isotopes are
  undergoing decay

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What is Ionizing Radiation?

• There are 2 types of radiation
• sub-atomic particles
• electromagnetic waves
• Typically, particles are parts of atoms
• alpha (helium nucleus)
• beta (electron)
• positron (positive anti-electron)
• neutron (component of nucleus)
• You can find exotic particles in cosmic ray and
  at high energy accelerators

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What is Ionizing Radiation? (contd)

• Electromagnetic waves are
• Like light or radio-waves you cannot see
• Emitted in packets of energy called photons
• X-Ray
• Gamma Ray

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What is Ionizing Radiation? (contd)

• Gamma Rays
• from nucleus of atom
• from annihilation of electron and positron
• X-Rays
• from orbital electrons
• from high energy electrons (and positrons)
  slowing down (call Bremsstrahlung)
• Ionizing radiation has enough energy to strip
  electrons off of atom or molecule

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Where do isotopes come from?

• Primordial isotopes
• Uranium series
• Thorium series
• Radium series
• Potassium-40 (K-40)

• Continually produced by natural process
• H-3, C-14
• Generated through mans activity
• Tc-99m, Cs-137, Pu-239

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Where do we get most of our radiation exposure?

• We live in an ocean of radiation
• Radiation comes from earth, space, and food we
  eat
• Life on earth evolved and flourished in higher
  level of natural radiation than today

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Natural Sources of Radiation
Cosmic Ray High energy radiation from the sun and
deep space
Terrestrial Radiation Radiation emitted from
natural radioactivity in soil, minerals and rocks
Nuclide Deposition Radiation from natural
radioactivity in our bodies, from food and air
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Space Weather
The sun emits both electromagnetic radiation and
electrically charged particle streams which can
interact with the near-earth environment. These
radiations vary in intensity over time
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Man-made Sources of Radiation

• Nuclear Medicine
• Radioactive tracers for diagnostic therapy
• Analytical procedures
• Pacemakers
• Medical X-Rays (produced by x-ray tubes)
• Fluoroscopy
• Chest X-Ray
• Dental X-ray

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Man-made Sources of Radiation (contd)

• Consumer products
• Television sets
• Smoke detectors
• Fossil fuel coal, gas
• Air travel
• Luminous compounds
• Building materials
• Nuclear fuel cycle
• Above-ground bomb tests

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Can you become radioactive if you get exposed to
radiation?

• You are already radioactive
• Radioactivity is a nuclear process
• Radiation we encounter day-to-day only affects
  electrons around the nucleus
• If you come into a dark room from sunlight, can
  others see you glow in the dark?
• If you heat your food in microwave oven, does the
  food emit microwave as you are eating it?
• Radioactivity can be induced only if exposed to
  neutron or beam from an accelerator

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How much radiation exposure is allowed per year?

• Radiation Worker
• Whole body 5,000 mrem
• Lens of the eye 15,000 mrem
• Skin 50,000 mrem
• Extremity 50,000 mrem
• Pregnant radiation worker 500 mrem
• for the entire gestation period
• Fetus is radiation sensitive due to rapidly
  dividing cells
• General Public
• Whole body 100 mrem
• up to 500 mrem w/prior authorization

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How much radiation dose do we receive from Mother
Nature?

• 300 mrem/year (national average)
• It increases with
• elevation
• latitude
• It varies with
• geology of the area where you live
• type of food you eat
• type of homes you live in
• your lifestyle (smoking, air travel, etc.)
• If you live in Denver, youll receive more
  radiation from cosmic ray and granite

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Radiation Effects

• Radiation Effect depends on
• How much radiation dose you receive
• How quickly you receive the dose
• What part of the body receives it, and
• whether you receive any medical treatment
• Radiation sensitivity depends on how rapidly
  cells divide

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Acute Radiation SyndromeWhole Body Exposure

• Hemopoietic syndrome (gt200,000 mrads)
• Depression or ablation of bone marrow
• Malaise and fatigue, epilation
• Potential death due to infection if no medical
  treatment given
• Gastrointestinal syndrome (gt1,000,000 mrads)
• Desquamation of intestinal epithelium
• Severe nausea, vomiting, diarrhea
• Central nervous system syndrome (gt2,000,000
  mrads)
• Damage to central nervous system other body
  organs
• Unconsciousness within few minutes

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How does ionizing radiation cause cell and tissue
damage?

• Direct damage to DNA
• DNA damage is expressed only when damaged cells
  divide
• Most of the damaged DNA are repaired. If not, the
  cell may die or a tiny fraction may persist

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How does ionizing radiation cause cell and tissue
damage? (contd)

• Indirect damage through formation
• of hydroxide free radicals
• (hydrogen peroxide)
• Free radicals may damage DNA
• At extremely high dose, cells are killed by
  damage to cell membrane from high levels of
  radicals

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How much DNA damage will I get?

• Recent study shows 10,000 mrem of radiation (2x
  the annual limit for workers) causes 200 single
  strand and 4 double strand breaks per cell
• This study also shows chemical and thermal
  effects (from day-to-day living) cause 150,000
  single strand and 200 double strand breaks per
  cell per year

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How much DNA damage will I get? (contd)

• Typical American receives 300 mrem of natural
  radiation per year
• So, 0.004 of DNA damage may be from natural
  radiation, and
• If radiation worker receives 5,000 mrem,
• lt0.07 of DNA damage may be from occupational
  radiation exposure

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How effective is radiation in causing DNA damage?

• In the study of cancer, researchers induce
  malignant transformation in cells
• Chemical carcinogens like benzopyrene is much
  more effective than radiation in producing cancer
  cells
• It may take 10,000s, if not 100,000s of mrads
  to produce the same effect as the amount of
  benzopyrene in a single cigarette

Dr. Ann Kennedy, University of Pennsylvania
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So, how come we are not all dropping dead of
cancer?

• On the average, about 1/3 of all people get
  cancer from all causes
• Currently, about 17 of people die from cancer
• Population of U.S. is about 300 million
• Eventually all those people would die
• 100 million would get cancer
• 50 million of those would die from cancer

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So, how come we are not all dropping dead of
cancer? (contd)

• Natural repair mechanism in our bodies eliminate
  most of the damaged cells
• Damaged cells that are not eliminated by the
  repair mechanism may become cancerous
• Cancer incidence rate rises with age
• So, if you live long enough, you will get cancer

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What is the likelihood that youll die from
cancer due to occupational exposure?

• Highly unlikely!

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Cancer Deaths Attributed to Various Sources

• Source Cancer Deaths ()
• Diet 35 Range 10 - 70
• Tobacco 30 Range 25 - 40
• Infection 10
• Sexual lifestyle 7 Range 1 - 13
• Occupation 4
• Alcohol 3
• Natural Environment 3
• Pollution 2
• Medical Care 1
• Food Additives 1
• Industrial Products 1
• Unknown -

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So why is there so much scare about radiation?

• We cant see it, smell it, or feel it
• It is not part of our daily experience
• Because of that, we do not have a proper
  perspective of the relative risks
• We read scary headlines
• Written by people who probably dont know any
  more than you do
• On the other hand, several dozen people die each
  day due to traffic accidents, but people continue
  to ride cars, trains and airplanes because we are
  used to it

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Radiation is a tool

• Radiation has many wonderful uses
• Diagnose disease
• Cure cancer
• Analytical tools for industry and medicine
• Sterilize medical equipment and food, etc
• Like anything, it can be misused, and
• Like anything, too much is not good for you

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What Safety Precautions should I take?

• Use Common Sense
• Not so common after all
• Time, Distance and Shielding
• Minimize Time
• Maximize Distance
• Maximize Shielding (heavier the better)
• Follow safety procedures

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History of Radiation Accidents

• Nearly all, if not all, radiation accidents were
  caused by workers
• not paying attention to what they were doing
• deliberately violating procedures
• deliberately circumventing safety devices
• Devices do fail occasionally, but good procedures
  and training would account for that possibility
• You can make the devices and procedures as
  Idiot-Proof as possible
• but those idiots can be very clever