rad bio chapter 18 /crb

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rad bio chapter 18 /crb
2012-11-07 23:09:24
rad bio chapter 18 crb

rad bio chapter 18 /crb
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  1. consist of 2 protons and 2 neutrons and are therefore simply helium nuclei
    alpha particles
  2. what are emitted from unstable heavy nuclei such as radium or radon during the decay process
    alpha particles
  3. because of their charge and heavy mass, what travel only short distances (can be stopped by a sheet of paper)
    alpha particles
  4. what produce intense ionization and are therefore high linerar energy transfer (High LET) radiation
    alpha particles
  5. what are extremely hazardous if ingested or inhaled but are less dangerous if the exposure is external (have greater biologic effect)
    alpha particles
  6. what is High LET
    High Linear Energy Transfer
  7. electrons emitted by the nucleus
    beta particles
  8. may be negatively charged (negatron) or postively charged
    beta particles
  9. negatively charged
  10. positively charged
  11. not stable and may exist for only very short periods of time
    positrons (beta particles)
  12. emitted and accompanied by a small massless, chargeless particle known as the neutrino
    beta particles
  13. small massless, chargeless particle
    neutrino (beta particles)
  14. which particles have the same rest mass as an electron and are usually emitted frome the nucleus with high velocities
    both types of particles
  15. what may be used for shielding, but bremsstrahlung radiation may result
    metals (beta particles)
  16. bremsstrahlun x-ray production is _____ proportional to the square of the _____ ____ of the absorber
    • directly proportional
    • atomic number
  17. bremsstrahlung x-ray production is ____ proportional to  the square of the mass of the _____ particle
    • inversely proportional
    • incident particle
  18. Thus, ____ _____ is much more likely to occur with beta particles then with alpha particles
    bremsstrahlung radiation
  19. bremsstrahlung radiation is much more likely to occur with ____ particles, than with ____ particles
    • beta
    • alpha
  20. rays both forms of electromagnetic radiation
    x-ray and gamma rays
  21. electromagnetic radiation
  22. have no mass and no charge
  23. photons emitted from a nucleus
    gamma rays
  24. extranuclear and result from rearrangements within the electron shells or from bremsstrahlung radiation
  25. gamma rays are emitted from
  26. x-rays are within
    electron shells
  27. except for their origins, there is no difference between ____ and ____
    x-rays and gamma rays
  28. the most common types of ionizing radiation used in radiation therapy
    • x-rays
    • gamma rays
    • electrons
  29. radiation with sufficient energy to separate an electron from its atom
    ionizing radiation
  30. alpha particles:
    charge number
    atomic mass
    • +2
    • 4
    • nucleus
  31. beta particles (negatron):
    charge number
    atomic mass
    • -1
    • 0
    • nucleus
  32. beta particles (positron):
    charge number
    atomic mass
    • +1
    • 0
    • nucleus
  33. Neutrinos:
    charge number
    atomic mass
    • 0
    • 0
    • nucleus
  34. x-rays:
    charge number
    atomic mass
    • 0
    • 0
    • electron shells
  35. gamma rays:
    charge number
    atomic mass
    • 0
    • 0
    • nucleus
  36. % for radon
  37. % for cosmic
  38. % for terrestrial
  39. % for internal
  40. % for medical x-rays
  41. % for nuclear medicine
  42. estimated % of all radiation exposure of the u.s. population comes from natural background sources
  43. estimated 82% of all radiation exposure of the u.s. population comes from ___ ___ ___ 
    natural background sources
  44. 3 sources of natural background radiation
    • cosmic rays
    • terrestrial radiation
    • internal
  45. rays that bombard the earth
    cosmic rays
  46. radiation that emanates from radioactive materials naturally occurring in the earth
    terrestrial radiation
  47. deposits of radionuclides in our bodies
  48. originate from nuclear reactions in space or from our own sun
    cosmic rays
  49. ____ ____ interact with molecules in the atmosphere to create other reactive agents known as ____ particles
    • cosmic rays
    • secondary particles
  50. with cosmic rays, exposure is ____ at the polar regions than at the equator
  51. with cosmic rays latitude, solar cycles and other factors may account for a variation of ___ % in exposure
  52. earth is made up of hundreds of materials, many of which are naturally radioactive
    terrestrial radiation
  53. terrestrial radiation are naturally radioactive because of teh presence of small amounts of  long-lived isotopes of ____, ____, and ____.
    • uranium
    • thorium
    • radium
  54. the largest exposure to terrestrial radiation involves
  55. may be particularly harmful because it is an easily inhaled gas
    radon (terrestrial radiation)
  56. what is EPA
    Environmental Protection Agency
  57. estimates that radon exposure is the second leading cause of lung cancer in the u.s.
    environmental protection agency (EPA)
  58. results from the radioactive materials that are normally present in our bodies
    internal exposure
  59. the amount of ionization produced by photons in air per unit mass of air
  60. traditional unit for exposure is
  61. the energy absorbed per unit mass of any material
    absorbed dose
  62. 1 Gy=100cGy=100 rad
    absorbed dose
  63. takes into account the fact that different types of radiation produce different amounts of biologic damage
    dose equivalent
  64. example of dose equivalent ____ ____ and ____ are high-LET radiation and therefore have a greater biologic effect than x-rays
    • alpha particles
    • neutrons
  65. takes into account the effect of irradiation of only part of the body or the effect of nonuniform irradiation of the body
    effective dose equivalent
  66. the rate at which the radioactive isotope undergoes nuclear decay
  67. traditional unit of activity is
    curie (Ci)
  68. 3.7 x 1010 disintegrations per second
    activity (Ci)
  69. the SI unit is ____ which is 1 disintegration per second in activity
    Becquerel (Bq)
  70. traditional unit for exposure
    1 roentgen
  71. traditional unit for absorded dose
    • 100 rad
    • 1 rad
  72. traditional unit for dose equivalent
    100 rem
  73. traditional unit for activity
    1 Ci
  74. quality factor (QF) for x-rays and gamma rays
  75. quailty factor (QF) for fast neutrons and alpha particles
    20 times that of x-rays
  76. this instrument has a chamber filled with gas that is ionized in part of whole when radiation is present
    gas-filled dectectors
  77. either the total quanity of electrical charge is measured or the rate at which charge is produced is measured
    gas-filled dectectors
  78. two kinds of gas-filled detectors may be found in a rad therapy dept
    • ionization chamber
    • Geiger-Muller (G-M)
  79. consist of two electrodes within a gas-filled chamber, an applied voltage across the electrodes & electronics
    ionizing chamber
  80. a meter to amplify and measure the electrical signal
    ionization chamber
  81. because of the sensitivity, they are best for finding contamination and other low levels of radiation
    G-M detectors (Geiger-Muller)
  82. when ____ ____ are properly calibrated, their accuracy approaches ___%, which makes them suitable for measurement of the radiation output of therapy equipment.
    • ionization chambers
    • 2%
  83. what is TLDs
    thermoluminescent dosimeters
  84. because of their small size, they are widely used to measure radiation in a number of applications
    thermoluminescent dosimeters (TLDs)
  85. as the name implies, thermoluminescent, materials give off light when ____.
  86. the ____ number of LiF is close to that of tissue
  87. if proper care is taken, ____ can be measured with and accuracy of approx ___%.
    • doses
    • 5%
  88. also used for mailed intercomparison of therapy unit calibration
    TLDs (thermoluminescent dosimeters)
  89. ring badges unsed for personnel monitoring & for measurements of environmental levels of radiation
    TLDs (thermoluminescent dosimeters)
  90. after development, x-ray film exposed to radiation turns ____
  91. on x-rays the amount of blackness is called
    opitical density
  92. related to the amount of radiation received by the film
    opitical density
  93. has a slot in which the film (in its protective paper cover) may be placed and serveral thin metal filters that surround portions of the film
    film badge
  94. filter allow discrimination between different types and energies of radiation
    film badge
  95. ______ radiation will not penetrate any of the filters but can reach the film in the area where no filters are present.
    low-energy (film badge)
  96. primary task is to analyze the existing data related to radiation exposure
    advisory agencies
  97. to assess the radiobiologic risks associated with those exposures
    advisory agencies
  98. these agencies can develop recommendations for dose limits
    advisory agencies
  99. the role is to license users of radioactive materials and radiation-producing equipment
    regulatory agencies
  100. inspect such users, and enforce the appropriate laws
    regulatory agencies
  101. one of the leading federal regulatory agencies in the u.s. is the
    nuclear regulatory commission (NRC)
  102. oversees the use of isotopes produced in nuclear reactors.
    • NRC (nuclear regulatory commission)
    • regulatory agency
  103. isotopes are commonly used in ____ ____ departments, in _____ and as sources for teletherapy (external beam radiation) and _____ (internal implants)
    • nuclear medicine
    • labs
    • brachytherapy
  104. with regulatory agencies, many states have entered into agreements concerning licensing, inspection and enforcement with ___ and have become "agreement" states.
    NRC (nuclear regulatory commission)
  105. as part of the agreement, states must maintain a certain level of _____ with NRC regulations
    • compatibility
    • regulatory agencies
  106. transportation of radioactive material is primarily the concern of _____ and the NRC
    • DOT (department of transportation)
    • regulatory agencies
  107. the use of machines that produce ionizing radiation, such as x-ray units and linear accelerators, fall under the jurisdiction of the ____________ and state agencies
    • food and drug administration (FDA)
    • regulatory agencies
  108. the EPA and _______ also have regulations that relate to the use of radiation.
    • OSHA (Occupational Safety and Health Administration)
    • Regulatory agencies
  109. we have a far greater knowledge of the effects of ____ doses of radiation than those of _____ doses.
    • high
    • low
  110. in sufficiently high quantities, radiation can be
  111. a single whole-body exposure of approx ___ cGy is lethal for ___% of the exposed population within ____ days of this event. Termed LD50/30
    • 4.5 cGy (450 rads)
    • 50%
    • 30 days
  112. even at levels below the lethal dose, there are significant long-term effects related to exposure to radiation. 2 general classifications
    • nonstochastic
    • stochastic
  113. are those for which a threshold exists and for which the severity of the effect increases with dose
    nonstochastic effects
  114. are those that have no threshold and for which the probabilty of occurance is a function of doses.
    stochastic effects
  115. the severity of the effect is not a function of the dose
    stochastic effects
  116. the regulatory requirements for limits for exposure to radiation for various groups, and practical methods for individual radiation protection
    ionizing radiation
  117. contribute to the annual dose to individuals
    man-made sources
  118. a form of ionization chamber, this is used for personnel monitoring
    pocket dosimeter
  119. examples of nonstochastic effects are:
    • erythema (skin reddening)
    • epilation (loss of hair)
    • cataract formation
    • infertility
  120. threshold doses for these effects are relatively high, which is reflected in the higher permitted doses tothe specific organs involved.
    nonstochastic effect
  121. *note*
    overall risk of exposure to radiation is approx 7 in 10,000 persons per rem.
  122. what is ALARA
    As Low as Reasonably Achievable
  123. the less radiation received, the lower the risk
  124. practical radiation protection from the external beam radiation should include the time-honored methods of
    • time
    • distance
    • shielding
  125. rate of nuclear decay
  126. the source of ionizing radiation that contributes the most to exposure of the general population in the u.s. is
    natural background radiation
  127. which type of device is best suited for output measurements of radiation therapy equipment
    ionizing chamber
  128. stochastic, or nonthreshold, effects of radiation exposure include:
    • cancer induction
    • genetic effects
    • birth defects
  129. exposure of which of group of people would contribute the most to the genetically significant dose
    20 year old woman
  130. the annual effective doe equivalent limit for radiation works is
    50 mSv
  131. G-M detector is 2 m form a small brachytherapy source and measure rate of 10 mR/hr. what exposure rate would you expect to measure if the detector were moved to 4 m from the source
    2.5 mR/hr
  132. energy absorbed per unit mass
    absorbed dose
  133. ionizing per unit mass of air by photons
  134. short range, relatively heavy-mass, high-LET particle
    Alpha particle