Rev Please Be Courteous To Others Deactivate all cell phones and pagers at this time!

Rev Properties of Ionizing Radiation Kyle Thornton RADL 70

Rev Ionizing Radiation Produces positively and negatively charged particles Man-made or natural Can be particulate or electromagnetic waves m/watch?v=K_zc1WKT 0CA m/watch?v=K_zc1WKT 0CA

Rev Picture of Alpha Particle

Rev Particulate Radiation Alpha radiation  Made of four particles Two protons – two neutrons  Does not penetrate matter easily  Large/slow moving  Carries a lot of energy  Interact with matter very quickly  Could not penetrate a piece of paper  Dangerous if taken inside the body  Personnel monitoring is not normally sensitive to alpha particles

Rev m/watch?v=Lg9coTz43 K0 m/watch?v=Lg9coTz43 K0

Rev Sources of Alpha Radiation Alpha EmitterAtomic Number Americium Plutonium Uranium Thorium Radium Radon Polonium 21084

Rev Sources of Alpha Radiation Uranium decays to Radium which decays to Radon  Radon is a gas, easily inspired into the body  Radon daughter (decay) products include polonium, bismuth and lead

Rev Uses of Alpha Radiation Americium 241  Used to power smoke alarms by creating an electrical current Radium 226  Used to treat cancer – brachytherapy implants Polonium 210  Used as a static eliminator in paper mills and other industries

Rev Particulate Radiation - Beta  Produced only in or near nucleus of an atom  Mass is about 1/2000 the size of a proton or neutron  Contains mainly high speed electrons  Behave similarly to a speeding bullet

Rev Beta Particle Production Created when ratio of protons to neutrons is too high An excess neutron is converted to a proton and electron Gamma ray production often accompanies this process

Rev Beta Radiation Production

Rev Comparison of Particulate/Electromagnetic Energy m/watch?v=ec8iomUS3 4U m/watch?v=ec8iomUS3 4U

Rev Sources of Beta Particles Tritium Cobalt-60 Strontium-90 Technetium-99 Iodine-129 and -131 Cesium-137

Rev Uses for Beta Particles Iodine 131  Used to treat thyroid cancers and Graves disease Carbon 14  Used to date organic matter up to 30,000 years old Tritium  Used for luminous dials, i.e., wristwatches, etc

Rev Electromagnetic Spectrum

Rev Electromagnetic Types Of Ionizing Radiation Gamma Rays  Monoenergetic waves of energy, able to penetrate most matter  Identical to x-rays in energy, wavelength, and frequency  Produced in nucleus  Generally emitted from radioactive materials

Rev Uses of Gamma Rays Cesium 137  Cancer treatment Cobalt 60  Cancer treatment  Pasteurizing food Technitium 99m  Diagnostic Imaging Studies

Rev X-Rays Similar to gamma – no mass or charge  Produced outside nucleus Accelerating electrons in a vacuum Having them strike a metal target  Highest energy of all electromagnetic waves shortest wavelength, highest frequency

Rev Physical Properties Of X-Rays Most penetrating electromagnetic waves They are heterogenous Polyenergetic Travel in a straight line Isotropic - Travel in different directions Affect photographic film Ionize all matter including gases Cause biologic changes

Rev Physical Properties Of X-Rays Cannot be focused by a lens Do not reflect off of surfaces Electrically neutral Produce secondary and scattered radiation Cause crystals to fluoresce

Rev Uses Of X-Rays Diagnostic Radiography  Fluoroscopy  Tomography  Mammography  Computed Radiography  Computed Tomography  Industrial uses  Authenticate paintings Therapeutic Radiology

Rev Linear Accelerator

Rev Schematic of Linear Accelerator

Rev Linear Accelerator

Rev Linear Accelerator Therapeutic units operate below 20 mA Times are around minutes Energies are around MV for x-ray beams For electron beams MeV is used Linear accelerators are used to treat neoplastic growths, physics research, and to produce radionuclides

Rev Filtration and Half value layer Filtration  Used to remove low energy, long wavelength x-ray photons  Inherent in the x-ray tube itself  Filtration is added by placing aluminum, molybdenum, or rhodium plates in the x-ray beam path Half-value layer  Measures beam quality  Amount of material necessary to reduce beam to half its intensity  Reduces patient dose

Rev History Of Radiation Units Somatic damage apparent shortly after Roentgen’s discovery of X-rays The need to limit exposure became apparent In order to limit exposure, a means of measurement was necessary First unit was known as skin erythema dose  This amount corresponded to a few hundred rads  Skin erythema threshold varies from person to person

Rev Evolution of Radiation Units The failure of the skin erythema dose as a unit necessitated another means of measurement The Roentgen took its place as the accepted unit of x and gamma radiation Today, both the international and traditional systems are used

Rev Radiation Units Roentgen - Coulombs/Kilogram – Air Kerma  Ionization in air Produced by gamma or X-rays 1 R = 2.58 X 10 (-4) C/Kg Gy a – Grays in air

Rev Absorbed Dose Rad - Gray  Radiation absorbed dose Amount of energy absorbed per unit mass of the object Depends on atomic number of the tissue, mass density, and incoming photon energy  One Gray = 100 Rads  Can be used for any type of radiation  Biologic effect varies with type of radiation 1 rad of X-ray does less harm than 1 rad beta radiation

Rev Occupational exposure Rem - Sievert  Radiation equivalent man  Unit of biological effect  Rem = Rad X Quality factor  Used for personnel monitoring  1 Sievert = 100 Rem

Rev Radioactivity Curie - Bequerel  Measures nuclear disintegration  Not an exact measurement  Curie = 3.7 X 10 (10) disintegrations/second  Bequerel = One decay/second

Rev Dose Equivalent Provides a means to calculate effective dose for different types of ionizing radiation  Protons - Charge is equal in magnitude to electron Mass is 1800 X greater  Neutrons - Electrically neutral Mass slightly higher than proton  Equal absorbed doses of these types will produce different amounts of biological damage

Rev Quality Factor Used to determine dose equivalency Absorbed dose is multiplied by this factor Evaluates relative hazard associated with different types of radiation  X-rays, beta particles, gamma photons, slow moving external protons have a QF of 1  Thermal neutrons - 5  Low energy internal protons – 20  Fast neutrons, alpha particles - 20

Rev Linear Energy Transfer Amount of energy transferred in a medium per unit of path length This is an average amount expressed in kiloelectron volts/micrometer Low LET radiation does not transfer much energy in matter along its path  X-rays fit in this category High LET radiation transfers a lot of energy to a small area and generally do more damage High LET radiation penetrates poorly, and poses more of a risk internally  High LET radiation has a high quality factor

Rev Stochastic Effects Nonthreshold, randomly occuring biologic effects from radiation  Cancer  Genetic abnormalities

Rev Non-Stochastic Effects Deterministic effects from known amounts of radiation  Blood changes  Temporary sterility