Radiation

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Radiation Tuesday, Sept 27
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Atom basic building block of matter Atoms
contain 3 types of particles protons ()
neutrons (no charge), and electrons (-).
Electrons are in orbit around the nucleus. All
matter is made up of elements fundamental
substances that cannot be broken down by chemical
means.
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Radiation light energy that travels and spreads
out as it goes - energy in transit in the
form of particles and electromagnetic
waves Electromagnetic radiation all the
wavelengths of light energy that make up visible
light, radio and TV waves, ultraviolet waves,
microwaves, and ionizing radiation Visible light,
radio and TV waves, ultraviolet waves, microwaves
do not carry enough energy to separate
molecules or remove electrons from atoms Ionizing
radiation radiation with enough energy to
remove tightly bound electrons from their orbits,
causing the atom to become charged or ionized
(electrically charged ions formed) Can destroy
chemical bonds in tissue and in DNA.
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Sources of ionizing radiation
sun, rocks, soil, past nuclear
weapons, radioactive medical and industrial
wastes, nuclear and coal power plants security
check devices Exposed to higher amounts at high
altitudes, in certain jobs, certain medical
treatments
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• Categories of origin
• Cosmic radiation from sun and space
• More at high altitudes atmosphere (ozone
  layer) helps protect earth. Denver gt LA or
  Boston
• 2. Radioactive materials in earths crust
  soils, rocks, sands. Radioactive gases escape
  from these (Radon) and enter air and water.
• 3. Manmade for industrial, medical (Xrays and
  labeled drugs) and dental, and consumer use
  Nuclear weapons nuclear power plants
• Radon gas is considered an enhanced natural
  source concentrates in houses and mine shafts,
  etc due to human actions
• Estimated that 82 of our exposure is from
  natural and enhanced natural sources. Harm
  relates to type and exposure pathway.

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4 types of ionizing radiation Alpha particles
beta particles gamma rays, x-rays Differ by
particle source, energy and speed, penetrability,
and consequent ability to do harm. Gamma and
x-rays are worst.
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• Alpha particles
• fast moving bits of atoms that are given off by a
  radioactive substance (fragments contain 2
  protons and 2 neutrons)
• Velocity is 1/20th the speed of light (slow)
• Natural elements can be alpha emitters
  uranium-238 thorium-232 radium-226 radon-222
  polonium-210 found in rocks , soils, and water
• Useful in some medical and industrial processes
• Radium-226 used to treat cancer by putting
  it into the tumor to kill the cells Polonium-210
  used as a static eliminator in paper mills (alpha
  particles attract loose electrons and reduce
  static charge) Americium-241used to create a
  current in smoke detectors. Smoke breaks the
  current and sets off alarm.
• Released during some mining operations
• - For most, greatest exposure is radon gas or
  smoking
• Health Effects lack energy to penetrate skin
  problem if inhaled or ingested or if enter blood
  through a wound.
• Lung and other cancer risks.

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• 2. Beta Particles
• Fragments of atoms that originate from nucleus
  and become like electrons
• A little smaller than alpha particles
• Speed varies over a wide range
• technetium-99 phosphorus-31 tritium H-3
  carbon-14, strontium-90 cobalt-60 iodine-129
  and 131
• used in medical diagnosis, imaging, and
  treatment luminous dials on gauges, and wrist
  watches carbon-14 used to date matter up to
  30,000 years of age other industrial measuring
  instruments
• Health effects can burn skin travel further
  into tissues than alpha particles ingestion and
  inhalation a worse problem than for alphas
• Dont play with instruments or devices that are
  marked with radioactive sign.

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• 3. Gamma rays
• very short wavelengths fastest in natural
  spectrum
• travel at speed of light
• easily pass through many materials lead shield
  needed
• differ from X rays in that gamma rays come from
  the nucleus and x-rays come form the electron
  field surrounding the nucleus
• most widely used radiation source
• cesium-137 cobalt-60 technetium-99m (shorter
  half-life)
• Cesium-137 cancer trt investigate deep in
  earth for oil wells measure soil density at
  construction sites quality control of fill
  levels in food and drug packaging
• Cobalt-60 sterilization of medical equipment
  pasteurization of foods and spices gauge metal
  thickness in steel manufacturing cancer trt
• Technetium -99m common radioactive isotope in
  medicine
• - Gamma ray trts also improve durability of wood
  and plastics

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• 3. Gamma rays (cont)
• Used to check seals on welds to inspect jet
  engine blades and parts
• Common sources of exposure natural occurrence in
  potassium in soil, water, bananas, meats nuclear
  medicine for bone, thyroid, lung scans.
• Medical trts discarded medical or industrial
  devices.
• External exposure inhalation ingestion all a
  problem.
• Penetrate tissue more deeply can cause
  radiation sickness at high doses (possibly
  lethal) lower doses cancer and neural damage,
  etc.

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4. X rays manmade source Most exposure through
diagnostic medical and dental x-rays. Penetrate
deeply. Like Gamma, but different source.
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• Routes
• Inhalation
• - chief concerns are contaminated dust, smoke,
  or gases (like Radon)
• - mostly alpha and beta particles
• - particles can lodge in lungs and remain for a
  long time
• - if particles decay slowly, exposure continues
  over a long time
• The amount of time it takes to decay one half of
  the radioactive atoms in a group to another form
  is called half-life.
• 2. Ingestion
• - Alpha and beta are of most concern
• - energy released directly to tissue (digestive
  kidney, and bone)

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Routes 3. External exposure - little concern
about alpha particles more about Beta most
about Gamma and xray. Gamma and x ray can
penetrate the entire body. (should be shielded
by lead apron or container soil covering buried
contaminations)
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• Health Effects
• Amount and duration of exposure determines health
  effects.
• Acute effects short term effects from high
  doses
• Radiation sickness nausea, vomiting, weakness,
  hair loss, skin burns, diminished organ function

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Health Effects II. Chronic long term, low
level Cancer is a primary health effect 1910
understood that radiation causes skin cancer Best
studies of chronic effects are on Japanese atomic
bomb survivors natives of Marshall Islands
(where bomb testing was done) and uranium
miners. Radiation changes DNA mutationa
caused.
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