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2010-11-29 21:56:14

radiation biology
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  1. what is ionization a production of?
    unblanced atom
  2. ionization results in two things what are the?
    • positive atom
    • dislodged negative electron
  3. how does radiation injury occur
  4. radiation injury results when x-rays strike _____
  5. x-ray photons interact with _____ ----> ______, excitation and ______ ----->______ changes ----> ______ changes
    • tissues
    • ionization
    • breaks bond
    • chemical
    • biologic
  6. ionization causes _____ changes
  7. through the formation of what does xradiation cause cell damage?
    free radicals
  8. what is defined as an uncharged atom or molecule that exists with a single unpaired electron in its outermost shell
    free radical
  9. when do free radicals form
    when the xray photon ionizes water
  10. what happens when an xray photon ionizes water?
    produces hydrogen and hydroxyl free radicals
  11. what is the primary component of a living cell
  12. what three things may a free radical do to achieve stability
    • recombine without causing changes in the molecule
    • may combine with other free radicals and cause changes
    • combine with ordinary molecules to form a toxin capable of producing widespread cellular changes
  13. what is an example of a free radical combining with an ordinary molecule to form a toxin?
    hydrogen peroxide
  14. what are two theories used to describe how radiation damages biologic tissues?
    • direct theory
    • indirect theory
  15. which theory suggests that cell damage results when ionizing radiation directly hits critical areas or targets within the cell.
    direct theory of radiation injury
  16. _____ theory occurs infrequently compared to ______ theory which occurs more frrequently
    • direct
    • indirect
  17. direct theory occurs ______ compared to indirect which occurs _______
    • infrequently
    • frequently
  18. what is an example of direct theory
    xray photon directly striking the DNA of the cell
  19. what theory suggestst that xray photons are absorbed within the cell and cause the formation of toxins, which in turn damage the cell
    indirect theory of radiation injury
  20. what is an example of indirect theory
    xray photons absorbed by water forming a free radical
  21. what does the combination of free radicals cause?
    cellular dysfunction and biologic damage
  22. why does indirect theory occur more frequently?
    because of the high water content of the cells
  23. what can be used to correlate the response or damage of tissues with the dose or amount of radiation received
    dose response curve
  24. t/f there is a safe amount of radiation exposure
    false! No safe amount!!
  25. what are the two classifications for biologic effects from radiation
    • stochastic effects
    • nonstochastic effects
  26. which biologic effects occur as a direct function of dose
  27. _____ effects do not have a dose threshold
    stochastic effects
  28. stochastic effects _____ have a dose threshold
  29. what are some examples of stochastic effects
    cancer (tumor) induction and genetic mutations
  30. the probability of stochastic effects occurrence _____ with increasing absorbed dose
  31. does the severity of the stochastic effects depend on the magnitude of the absorbed dose
    No it does not depend on magnitude of absorbed dose
  32. nonstochastic effects is also known as?
    deterministic effects
  33. what are somatic effects that have a threshold and that increase in severity with increasing absorbed dose
    nonstochastic effects (deterministic effects)
  34. what are some examples of nonstochastic effects?
    • erythema
    • loss of hair
    • cataract formation
    • decreased fertility
  35. what biologic effect has these examples: erythema, loss of hair, cataract fomation and decreased fertility
  36. nonstochastic effects require more or less radiation than stochastic to cause serious impairment of health.
  37. t/f nonstochastic effects require larger radiation doses to cause serious impairment of health
    true true
  38. _____ effects are genetic but _____ effects are ones you can see
    • stochastic
    • nonstochastic
  39. _____ _____ that follow absorption of radiation occur rapidly at a molecular level
    chemical reactions
  40. t/f observable effects of radiation are visible immediately after exposure
    false-no visible immediately after
  41. what is the time that elapses between exposure to ionizing radiation and the appearance of observable clinical signs
    latent period
  42. what determines the length of the latent period?
    total dose of radiation received and amount of time or rate it took to receive the dose
  43. what is the sequence of radiation injury
    • chemical reactions
    • latent period
    • period of injury
    • recovery period
  44. what is involved in the period of injury?
    cellular injuries
  45. what are some examples of cellular injuries during the period of injury (6)
    • cell death
    • changes in cell function
    • breaking or chumping of chromosomes
    • formation of giant cells
    • cessation of mitotic activity
    • abnormal mitotic activity
  46. what is the last event in the sequence of radiation injury
    recovery period
  47. are all cellular radiation injuries permanent?
    no-not all cellular radiation injuries are permanent
  48. cellular damage is followed by what?
  49. ____ _____ radiation damage is repaired within the cells of the body
    low level
  50. where is low level radiation damage repaired?
    in the cells of the body
  51. what is it called when repeated radiation exposure leads to health problems
    cumulative effects
  52. effects of radiation exposure are _____ and ____ damage accumulates in the tissues
    • additive
    • unrepaired
  53. what is defined as the quantity of radiation receive or the total amount of radiation energy absorbed.
    total dose
  54. t/f more damage occurs when tissues absorb large quantities of radiation
    true(total dose)
  55. what is defined as the rate at which exposure to radiation occurs and absorption takes place
    dose rate
  56. t/f more radiation damage takes place with high dose rates because a rapid delivery of radiation does not allow time for the cellular damage to be repaired
    true (dose rate)
  57. what is defined as the areas of the body exposed to radiation
    amount of tissue irradiated
  58. ____ _____: more damage occurs in cells that are most sensitive to radiation such as rapidly dividing cells and young cells
    cell sensitivity
  59. what age group is more susceptible to radiation
  60. radiation effects in hematopoietic tissues causes?
  61. what tissues would you need to radiated to cause leukemia
    hematopoietic (blood forming) tissues
  62. what are the radiation effects with the reproductive cells?
  63. which tissues or organs have the radiation effect of carcinoma? (2)
    • thyroid
    • skin
  64. what radiation effect do you get with the thyroid?
  65. what radiation effects do you get with the skin?
  66. what radiation effects do you get with the eyes
  67. following the latent period effects seen within minutes days or weeks are termed what?
    short term effects
  68. what are shor term effects associated with?
    large amounts of radiation absorbed in a short time
  69. what is ARS?
  70. what are the symptoms of ARS?
    • nausea
    • vomiting
    • diarrhea
    • hair loss
    • hemorrahage
  71. are short term effects of radiation applicable to dentistry?
  72. what are effects that appear after years, decades or generations?
    long term effects
  73. what are long term effects associated with?
    small amounts of radiation absorbed repeatedly over long period
  74. what are low levels of radiation exposure linked with?
    • cancer
    • birth abnormalities
    • genetic defects
  75. what is ARS associated with?
    short term radiation effects
  76. all the cells in the body can be classified either ____ or ____
    • somatic
    • genetic
  77. what are the somatic cells in the body?
    all the cells in the body exept the reproductive cells
  78. what are the genetic cells in the body
    genetic cells
  79. _____ effects are seen in the person being irradiated
  80. _____ effects are not seen in the person irradiated but are passed on to future generations
  81. what do changes in somatic cells produce?
    poor health
  82. what are major somatic effects of radiation exposure?
    • cancer
    • leukemia
    • cataracts
  83. t/f somatic effects are not transmitted to future generations
  84. t/f genetic damage can be repaired
    FALSE!! cannot be repaired (future generations is just screwed)
  85. the cell ____ is more sensitive to radiation than the ____
    • nucleus
    • cytoplasm
  86. damage to the cell nucleus affects what?
    the chromosomes containing the DNA
  87. damage to the cells DNA results in what?
    disruption of cell division (disrupt cell function or cell death)
  88. what is a cell that is sensitive to radiation called?
  89. what is is a cell that is resistant to radiation called?
  90. what are three things that determine the response of a cell to radiation exposure?
    • mitotic activity
    • cell differentiation
    • cell metabolism
  91. how does mitotic activity determine the response of the cell to radiation exposure?
    cells that divide frequently or undergo many divisions over time are more sensitive to radiation
  92. how does cell differentiation determine the response of the cell to radiation exposure?
    cells that are immature or are not highly specialized are more sensitve to radiation
  93. how does cell metabolism determine the response of the cell to radiation exposure
    cells that have higher metabolism are more sensitve to radiation
  94. what are 3 examples of radiosensitive cells?
    • blood cells
    • immature reproductive cells
    • young bone cells
  95. what is the cell that is most sensitive to radiation?
    small lymphocyte
  96. what are 3 radioresistant cells?
    • bone
    • muscle
    • nerve
  97. what are 4 examples of radiosensitive organs?
    • lymphoid tissues
    • bone marrow
    • testes
    • intestines
  98. radiosensitive organs are composed of ______ cells
  99. what are 3 examples of radioresistant tissues?
    • salivary glands
    • kidney
    • liver
  100. how is an organ classified as a critical organ?
    if the organ is damaged it diminishes the quality of a person's life
  101. if an organ is damaged and diminishes a person's life what is that organ classified as?
    critical organ
  102. what are critical organs involved in dentistry (4)
    • skin
    • thyroid
    • lens of the eye
    • bone marrow
  103. what is the ICRU
    international commission on radiation units and measurement
  104. what quantities of radiation are the ICRU measurements used to define? (3)
    • exposure
    • dose
    • dose equivalent
  105. what are the two systems used to define radiation measurements
    • tradition system or standard system
    • SI system or International system of units
  106. what are the traditional units of radiation measurements
    • roentgen (R)
    • radiation absorbed dose (rad)
    • roentgen equivalent in man (rem)
  107. what are the SI units of radiation measurement?
    • coulombs/kilogram (C/kg)
    • gray (Gy)
    • sievert (Sv)
  108. what is defined as the measurment of ionization in the air produced by exrays
  109. the traditional nit of exposure for xrays is?
    roentgen (R)
  110. what is defined as the quantity of xradiation or gamma radiation that produces an electrical charge or 2.58 X 10-4 coulombs in a kilogram of air at standard temperature and pressure conditions
  111. the roentgen is limited to measurements in the ____ it cannot measure amount of radiation _____
    • air
    • absorbed
  112. what is a coulomb?
    unit of electrical charge
  113. what is the conversion of 1 R to a C/kg?
    1 R=2.58 X 10-4 C/kg
  114. what is the conversion of 1 C/kg to R?
    1 C/kg= 3.88 x 103 R
  115. what can be defined as the amount of energy absorbed by a tissue
  116. what is the traditional unit of dose?
    radiation absorbed dose (rad)
  117. t/r the rad is not restricted to air?
  118. what is a special unit of absorbed dose that is equal to the deposition of 100 ergs of energy per gram of tissue
  119. what is the SI unit equivalent to the rad
    gray (Gy)
  120. what is the conversion for 1 rad to the gray
    1 rad=0.01Gy
  121. what is the conversion for 1 gray to rads
    1 gray=100 rads
  122. what is the measurement used to compare biologic effects of different types of radiation
    dose equivalent
  123. what is the tradition unit of dose equivalent
    roentgen equivalent man or rem
  124. what is the product of absorbed dose (rads) and a quality factor specific for the type of radiation
  125. what is used to place the exposure effects of different types of radiation on a common scale
    quality factor or dimensionless multiplier
  126. what is the SI unit for equivalent of the rem?
    sievert (Sv)
  127. what is the conversion for 1 rem to Sv
    1 rem=0.01 Sv
  128. what is the conversion for 1 Sv to rems
    1 Sv=100 rems
  129. in dental radiograph the gray and the ____ are equal and the roentgen ____ and ____ are considered approximately equal
    • seivert
    • rad
    • rem
  130. what prefix is used to accommodated the small doses of radiation used?
  131. what is the daily exposure of radiation that humans undergo called?
    background radiation
  132. what is cosmic radiation?
    originates from the stars and sun
  133. what does a persons exposure to cosmic radiation depend on?
  134. what is terrestrial radiation?
    emitted from radioactive materials present in the earth and air
  135. what is an example of terrestrial radiation?
    postassium-40 and uranium
  136. what is artificial radiation?
    modern technology or man made
  137. what is the greatest contributor to artificial radiation?
    medical radiation
  138. the medical radiation exposure _____ the average yearly dose from all other exposures combinded
  139. what can be defined as the likelihood of adverse effects or death resulting from exposure to a hazard
  140. what is the risk in dental radiography
    cancer induction from ionizing radiation
  141. what is the potential risk of dental radiography inducing a fatal cancer in an individula?
    3 in 1 million
  142. what is the risk of a person developing cancer spontaneously
    3300 in 1 million
  143. what is an estimated dose necessary to produce cancer in the thyroid gland?
    6000 mrads
  144. what is the average dose to the thyroid gland with dental radiography?
    6 mrads
  145. what is the dose needed to cause leukemia?
    5000 mrads
  146. what is the average bone marrow dose in dental radiography?
    1 to3 mrads
  147. a total of ____ rads in a ____ day period causes erythema or reddening of the skin
    • 250
    • 14
  148. to produce erythema or reddening of the skin more than ____ dental films in ____ day period would have to be exposed
    • 500
    • 14
  149. how many mrads are necessary to induce cataract foramtion?
    200,000 mrads
  150. what is the average dose to the cornea during dental radiography?
    60 mrads
  151. dental radiographs should be prescribed for a patient only when?
    the benefit of disease detection outweighs the risk of biologic damage
  152. when dental radiographs are properly prescribed and exposed the ____ of disease detection ___ _____ the risk of damage from xradiation
    • benefit
    • far outweighs