Rad Protection

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Rad Protection
2011-06-04 21:45:09

rad protection
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  1. Natural background radiation
    radiation contained in the unpolluted environment
  2. Artificially produced radiaition
    also called man-made radiation
  3. Primary radiation
    radiation exiting the x-ray tube
  4. Exit radiation (remenent radiation; image-producing radiation)
    x-rays that emerge from the patient and strike the image receptor
  5. Attenuation
    absorption and scatter (loss of intensity) of hte x-ray beam as it passed through the patient
  6. Hetrogenous beam
    x-ray beam that contains photons of many different energies
  7. Photoeletric Effect
    absorption of x-ray photons in the atoms of the body
  8. Compton effect
    scatter of x-ray photons from the atoms of the body
  9. Roentgen (R)
    traditional unit of in-air exposure
  10. Coulombs per kilogram (C/kg)
    SI unit of in-air exposure
  11. Rad
    traditional unit of absorbed dose
  12. Gray
    SI unit of absorbed dose
  13. Rem
    traditional unit of eequivalent dose and effective dose
  14. Sievart
    SI unit of equivalent dose and effective dose
  15. Curie
    traditional unit of activity
  16. Becquerel
    SI unit of activity
  17. National Academy of Sciences/National Researche Councile Committee on the Biological Effects of Ionizing Radiation (NAS/NRC-BEIR)
    Study biologic effects of ionizing radiation protection guidelines
  18. Internation Commission of Radiological Protection
    Publishes internation radiation protection guidelines
  19. National Council on Radiation Protection and Measurements (NCRP)
    Published radiation protection guidelines for the United States
  20. Nuclear Regulatory Commission (NRC)
    Enforces radiation protection standards at the federal level related to use of radioactive material
  21. NCRP Report # 102
    Makes recommendations on equipment design and protection regarding lead shielding and fluoroscopic and mobile exposure rates
  22. NCRP Report # 116
    Makes recommendations pertaining to risk-benefit analysis of radiation exposure; states that somatic and genetic effects should be kept to a minimum when radiation is used for diagnostic imaging; defines annual exposure limits
  23. Effective dose limit
    The upper boundary dose that can be absorbed, either in a single exposure or annually, with a negligible risk of somatic or genetic damage to the individual; effective dose implies whole body radiation exposure
  24. Cumulative effective dose (CED)
    limit lifetime occupational exposure must not exceed the radiographer's age multiplied by 1 rem
  25. Equivalent dose
    equal to the absorbed dose multiplied by the radiation weighting factor; formerly known as dose equivalent
  26. Equivalent dose limit
    Upper boundary dose that can be absorbed, either in a singler exposure or annually, with a negligible risk of a deterministic levels
  27. ALARA (As Low As Reasonably Achievable)
    A concept of radiologic practice that encourages radiation users to adopt measures that keep the dose to the patient and themselves at minimal levels
  28. Dose-Response Curve
    graphs taht illustrate the relationship between radiation dose and the response of hte organisim to exposure; may be linear or nonlinear, threshold or nonthreshold
  29. Stochastic Effects
    radomly occurring effects of radiation; the probabitlity of such effects id proportional to the dose (increased dose equal increased probability, not severity, of effects)
  30. Deterministic Effects
    Effects of radiation that become more severe at high levels of radiation exposure and do not occur below a certain threshold dose
  31. Genetically significan dose (GSD)
    Average annual gonadal dose of radiation to the individuals of childbearing age; addresses the relationship of gonadal doses to individuals versus and entire population and overall effects
  32. Linear Energy Transfer (LET)
    amount of energy deposited by radiation per unit length of tissue
  33. Relative biolgic effectiveness (RBE)
    Ability t oproduce biolgoic damage; varies with the LET
  34. Direct Effect
    occurs when raidaiton directly strikes DNA in the cellular nucleus
  35. Indirect Effect
    Occurs when radiaiton strikes the water molecules in the cytoplasm of the cell
  36. Radiolysis of water
    Occurs as radiation energy is deposited in the wate rof the cell; the result of radiolysis is an ion pair in the cell: a positively charged water molecule (HOH+) and a free electron
  37. Mutation
    Erroneous information passed to subsequent generation via cell division
  38. Law of Bergonie and Tribondeau
    Cells are most sensitive to radiation when they are immature, undifferentiated, and rapidly dividing
  39. Early Somatic Effects of Radiation
    hemopoetic syndrome, gastrointestional syndrome; central nervous system syndrome
  40. Late Somatic Effects of Radiation
    Carcinogenesis, cataractogenesis, embryologic effects, thyroid dysfunction, life span shortening
  41. Cardinal principles of Radiation Protection
    • Distance
    • Time
    • Shielding
  42. Distance
    Best protection against radiation exposure
  43. Personnel Monitoring Devices
    • Optically stimulated luminescence (OSL) badge
    • Film Badge
    • Thermoluminescent dosimeter (TLD)
  44. Mean Marrow Dose
    average dose of radiation to the bone marrow
  45. Ionization may cause
    unstable atoms, free elctrons , or formation of new molecules harmful to the cell
  46. What 2 types of damage can occur to the cell?
    • Somatic
    • and
    • Genetic
  47. What is the greatest source of natural radiation present in the environment?
  48. Where does 82% of human exposure come from?
    Natural Background Radiation
  49. Photelectric Interaction
    • Incoming x-ray photon strikes a K-shell electron
    • Energy of x-ray photon is transferred to electron
    • Electron is ejected from the K-shell and is now called a photoelectron
    • X-ray photon has depsoited all of its energy and ceases to exist
    • Photon has been completely absorbed
    • Photoelectron may ionize or excite other atoms until it has deposited all of its energy
    • Characteristic cascade happens to fill hole in K-shell
    • Produces contrast in image because of differential absorption of incoming x-ray photons
  50. Compton Interaction
    • Incoming x-ray photon stikes a loosely, bound outer-shell electron
    • Photon transfers part of it's energy to the electron
    • Electron is removed from orbit as a scattered electron, referred to as a recoil electron
    • Ejected electrons may ionize other atoms or recombine with an ion needing an electron
    • Scattered photon may interact with other electrons, causing more ioniziation, addition scattering events, or photoeletric absorption, or it may exit the patient
    • Scattered photons emerging from the patient travel in very divergent paths in random directions
    • Scattered photons may also be present in the room and expose the radiographer or radiologist
  51. Coherent Scatter (Classical Scattering or Thompson's Scattering)
    • Produced by low energy photons
    • Electrons are not removed but vibrate from deposition of energy from photon
    • As electrons vibrate they emit energy equal to original photon
    • Does not affect image under 70 kVp
  52. Pair Production
    • does not occur in radiography
    • produced a photon energies above 1.02 mEv
    • involves interacton between incoming photon and atomic nucleus
  53. Photodisintegration
    does not occur in radiography