11/9 Scott

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RadTherapy
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11/9 Scott
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2012-11-09 10:48:26
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11/9 Scott
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  1. Radiation with sufficient energy to seperate an electron from its atom
    ionizing radiation
  2. What are the 2 major groups of radiation sources?
    External Beam therapy machines

    brachytherapy sources
  3. Which source of radiation use gamma rays, x-rays, and sometimes electrons
    external beam

    such as cobalt teletherapy units or linear accelerators
  4. What source od radiation use gamma rays & x-rays from sources such as cesium-137, iridium-192, and iodine-125.
    brachytherapy
  5. **
    Consist of 2 protons and 2 neutrons and therefore are simply helium neclei
    Alpha Particles
  6. They are emitted from unstable heavy nuclei such as radium or radon during the decay process
    Alpha particles
  7. **
    Can only travel short distances.
    --most can be stopped by a sheet of paper, but they produce intense ionization and are therefore high linear energy transfer (LET) radiation
    Alpha particles
  8. They are extremely hazardous if ingested or inhaled but are less dangerous if the exposure is external
    Alpha particles
  9. **
    Electrons emitted by nucleus

    They may be either negatively or positively charged
    Beta particles
  10. Negatively charged beta particles are called
    negatron
  11. positively charged beta particles are called
    positrons
  12. _______ are not stable and may exist for only very short periods of time
    positrons
  13. **
    Whenever beta particles are emitted, they are accompanied by a small, massless, chargeless particles known as the
    neutrino
  14. metals may be used for shielding, but ____ radiation may result
    bremsstrahlung
  15. **
    The probability of bremsstrahlung x-ray production is ___
    ___ to the square of the atomic number of the absorber and ___ ___ to the square of the mass of the incident particle
    directly proportional

    inversely proportional
  16. **
    Bremsstrahlung radiation is much more likely to occur with ____ particles than with ____ particles
    Beta

    Alpha
  17. ____ & ____ are both forms of electromagnetic radiation (photons)
    x-rays & gamma rays
  18. **
    ____ have no mass and no charge
    photons
  19. **
    ____ are photons emitted froma nucleus
    gamma rays
  20. **
    _____ are extranuclear and result from rearrangements
    within the electron shells or from bremsstrahlung radiation
    x-rays
  21. **
    Except for their origin, there is no difference between ___ and ____.
    xrays & gamma rays
  22. NOTE:
    xrays, gamma rays, and electrons are the most common types of ionizing radiations
  23. It is estimated that ___% of the radiation exposure of the United States population comes from natural background sources
    82%
  24. What are the amounts of radiation exposure for

    natural _____%

    man made ____%
    82

    18
  25. What are the 3 sources of natural background radiation?
    Cosmic Rays

    Terrestrial Exposure

    Internal Exposure
  26. **
    The primary cosmic rays interact with molecules in the atmosphere to create reactive agents known as _____.
    secondary particles
  27. Whhat natural radiation originates from nuclear reations in spce or from our own sun
    Cosmic Rays
  28. Exposure is _____ at the polar regions than at the equator
    higher
  29. Latitude, solar cycels, and other factors may account for a variation of ___% in exposure.

    The intensity varies even more with increasing elevation
    10%
  30. What natural source is made up of small amounts of long lived isotopes of uranium, thorium, and radium among others
    terrestrial radiation
  31. **
    The ___ ___ ___ estimates that radon exposure is the 2nd leading cause of lung cancer in the U.S. (following smoking)
    • EPA
    •    Enviromental Protection Agency
  32. **
    ___ ___ results from the radioactive material that are normally in our bodies
    Internal exposure
  33. What are examples of man-made sources?
    xrays - nuclear medicine procedures, TV, tobacco products, nuclear reactors, fuel cycle, & fallout from above ground nuclear weapons testing
  34. **
    ___ is defined as the amount of ionization produced by photons in AIR per unit mass of air
    Exposure
  35. **
    ___ ___ is defined as the energy absorbed per unit mass of any material
    absorbed dose
  36. ___ Gy = ___ cGy = ___ rad
    • 1
    • 100
    • 100
  37. **
    ___ ___ takes into account the fact that different types of radiation produce different amounts of biologic damage
    dose equivelent
  38. Alpha particle & neutrons are __ ___ LET radiation and therefore have a greater biologic efect than x-rays
    high
  39. NOTE:
    To account for differences in biologic response, each type of radiation is assigned a quality factor
  40. What is the traditional unit of:
    Exposure:
    Absorced Dose:
    Dose Equivelent:
    Activity
    • roentgen
    • rad
    • rem
    • ci
  41. The QF of
    xrays & gamma rays=
    fast nuetrons=
    • 1
    • 20
  42. **
    ___ ____ ___ takes into account the effect of irradation of only part of the body or the effect of non uniform irradation of the body
    effective dose equivelent
  43. NOTE:
    The units for the effective dose equivelent are also the Sievert & the REM
  44. **
    ___ is the rate at which a radiaoactive isotope undergoes nuclear decay
    activity
  45. NOTE:
    The traditional unt of activity is the curie (CI)

    This SI unit is the becquerrel
  46. What are the 2 kinds of gas-filled detectors that may be found in a RT dept.
    ionization chamber

    Geiger Muller
  47. ** When ionization chambers re properly calibrated their accuracy approaches ___% which makes them suitable for measurement of the radiaiton output of therapy equipment
    2%
  48. What form of ionization chamber is used for personal monitoring
    the pocket dosimeter
  49. Note:
    becuase ionization chambers are not very sensitive, they are not suitable for the detection of very low levels of radiation or radiation contamination
  50. ** NOTE
    Because of their sensitivity, G-M detectors are best for finding contamination and other low levels of radiation
  51. **
    Because of their small size, ___ ___ are widely used to measure radiation in a number of applications
    TLD's thermoluminscent dosimeters
  52. **
    Thermoluminscent materials give offlight when heated
  53. The atomic number of LIF is close to that of tissue
  54. With proper care, doses can be measured with an accuracy of approximately ___ %
    5%
  55. **After development, x-ray film exposed to radiation turns black.
    This amount of blackness is called the ___ ___
    optical density
  56. NOTE:
    The optical denisty is the amount of radiation received by the film
  57. **
    The primary task of ___ ___ is to analyze the existing data related to radiation exposure and to access the radiobiologic risk associated with those exposures
    advisory agencies
  58. **
    It is the role of the ___ ___ to license users of radioactive materials & radiaiton-producing equipment, inspect such users, and enforce the laws
     
    regualtory agencies
  59. **
    many states have entered into agreements concerning licensing, inspection and enforcement with the NRC have become ___ states
    agreement
  60. effects have no threshold and for which the probability of occurance is a function of dose
    Stochastic

    ex: cancer induction, genectic effects and embryologic & teratogenic effects
  61. *
    ___ effects are those for which a threshold exist and for which the severity of the effect increases with dose
    non-stochastic

    • ex: erythema (skin reddness),
    • epilation (hair loss)
    • cataract formation
    • infertilty
  62. What are the significant long term effects related to exposure to radaition?
    nonstochaltic & stochastic effects
  63. WHat does the LD 50/30 means?
    lethal dose or 50% of the population in 30 days
  64. we have a far greater knowledge of the effects of high doses than those of low doses.

    In sufficiency high quanitites, radiation can be lethal.  A single whole body dose of 4.5 ___ is lethal for ___5 of the exposed population with in ___ days of the event
    • Gy
    • 50
    • 30
  65. what agency oversees the use of isotopes produced in nuclear reactors.
    These isotopes are currently used in nuclear med dept, labs as sources for teletherapy & brachytherapy
    • NRC
    • nuclear regulatory commission
  66. NOTE:
    TLD's are also used for mail intercomparision of therapy units calibration, in ring badges used for personal monitoring, and for measurements of enviromental levels of radiation.
  67. A typical ___ ___ has a slot in which the film may be placed and several thin, metal, filters that surround portions of the film.

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