HEALS Physics Hot Spots

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RadiationTherapy
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266479
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HEALS Physics Hot Spots
Updated:
2014-04-06 12:15:11
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radiation physics
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HEALS
Description:
HEALS Chapters 1-3
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  1. The chemical properties of an atom are primarily controlled by its ________ number.
    Valence
  2. The principle unit of energy measurement on the atomic scale is the:
    Electron Volt
  3. The chemical bond formed when two or more atoms share electrons is termed ________ bonding.
    Covalent
  4. The mass energy equivalent value for an electron is ________.
    .511 MeV
  5. The physical characteristics of the atom are controlled by the atom's __________ number.
    Atomic number (Z)
  6. The principle force involved with nuclear binding is the __________ force.
    Strong force
  7. The average nuclear binding energy that must be exceeded to remove nucleons from the nucleus is in the range of __________.
    5-8 MeV
  8. Atoms with different types of nuclear configurations are termed __________.
    Nuclides
  9. The term used to describe the process in which light nuclei combine to form a heavier nucleus is __________.
    Fusion
  10. The parent for the beta particle is most commonly a __________.
    Neutron
  11. The principle emission particle associated with the transformation of a proton into a neutron is __________.
    Beta +
  12. The most likely radionuclides undergoing spontaneous beta decay will possess an unfavorably high N-P ratio or have an excess of __________.
    Neutrons
  13. After beta decay, the daughter nuclide will have an atomic mass that is __________ the parent nuclide.
    The same as
  14. The emission of a beta particle is associated with the transformation of a __________ into a __________.
    Neutron into a Proton.
  15. The fraction of the remaining number of atoms that decay per unit time is called the __________.
    Decay constant.
  16. The ratio of the amount of energy lost by a charged particle as it traverses a given distance in a medium defines the __________.
    Absorbed dose
  17. As the energy of electromagnetic radiation increases:
    I. Frequency decreases
    II. Wavelength decreases
    III. Speed increases
    • II. only
    • As energy increases WAVELENGTH decreases
  18. The energy of the photons produced in Bremsstrahlung x-ray production is dependent upon the:
    I. Projectile speed
    II. Atomic number of the target
    III. Electron to nucleus distance
    I, II, III
  19. The x-radiation emission in an x-ray tube is considered to be ___________ in nature.
    Heterogenous
  20. The speed of all electromagnetic radiations in a vacuum is:
    3 x 1010 cm/sec
  21. The loss of an electron by an x-ray tube electron as it passes by a tungsten atom in the anode results in a photon being produced by an event termed:
    Bremsstrahlung
  22. When the stream of fast-moving electrons interact with the target of the anode, x-rays are generated by 2 different processes. They are:
    Bremsstrahlung & Characteristic radiation
  23. The reduction in the number and energy of photons as a radiation passes through matter is termed:
    Attenuation
  24. The use of linear attenuation coefficients are applied most commonly to:
    Monochromatic radiations
  25. The production of scattered radiation when radiation when x-radiation strikes an object principally results from the ___________.
    Compton event
  26. At photon energies of 100 keV to 1 MeV, radiation is absorbed in soft tissue mainly by the:
    Compton effect
  27. The concept of mass attenuation coefficients is employed to describe the attenuation of materials independent of its ___________.
    Density
  28. During a Compton interaction, the maximum energy of a photon scattered backwards at a 180 angle will be:
    .255 MeV
  29. The interaction of x-rays with matter that is most common in the energy range btw 150 keV and 3 MeV is V.
    Compton scatter
  30. The emission from an unstable nucleus with the highest ionization potential is:
    Alpha
  31. The linear attenuation coefficient of a monochromatic beam will tend to ___________ as the energy of the beam of radiation increases.
    Decrease
  32. As the atomic number of an attenuator increases, the linear attenuation coefficient will tend to:
    Increase
  33. The interaction of an x-ray photon and an orbital electron orbital electron, which results in a partial transfer of energy and ionization of the orbital electron is called:
    Compton effect
  34. Pair production is a common reaction occurring in the photon energy range of:
    1 - 10 MeV
  35. The number of Compton interactions is primarily dependent upon the ___________ of the target atom.
    Electron density
  36. At energies above 10 MeV, x-ray photons may interact directly with the atomic nucleus causing the emission of nuclear fragments in a process termed ___________.
    Photodisintegration
  37. The mass-energy equivalency of a positron or electron at rest velocity is:
    0.511 MeV
  38. The range of any charged particle is normally defined as the ___________ thickness of a material for which they are able to penetrate.
    Maximum
  39. The rate of energy loss during an inelastic collision of a beta-particle and an orbital electron is principally related to the material's:
    Electron density
  40. Neutron possessing low energies (.025 eV) are often referred to as _________ neutrons.
    Thermal
  41. The principal result from an interaction between charged particles that result in ionization or excitation is called:
    (elastic or inelastic)
    Inelastic
  42. Collisions of radiation with matter that result in no change of internal or kinetic energy of the collided pair is termed:
    (elastic or inelastic)
    Elastic
  43. The Sievert is the standard international (SI) unit used for the determination of:
    Dose equivalence
  44. The smallest detectable dose of a standard film monitoring badge is approx:
    A. 0.1mSv
    B. 100 mSv
    C. 1 Sv
    D. 10 mSv
    A. 0.1 mSv
    (this multiple choice question has been scrambled)
  45. The most sensitive type of personnel monitoring device is the:
    Pocket dosimeter
  46. The fraction of the number of photons removed from a radiation field per centimeter of absorbing material defines the _____________.
    Linear attenuation coefficient
  47. The dose delivery system needed to treat most cancers needs to have an accuracy of at least ____%
    5%
  48. An overhead sagittal laser light is useful in aligning the sagittal axis of the patient with the axis of the:
    Gantry
  49. A split field test is performed to check the alignment of __________ fields.
    Opposed fields
  50. A test consisting of a film shielded by two lead blocks exposed at two gantry positions 180° apart best describes a:
    Split field test
  51. The principle objective in performing field symmetry and flatness checks is the determination of dose rate _______ across the field.
    Consistency
  52. After a split field test is performed, the acceptable limit of shift between two parallel opposed fields is:
    3 mm
  53. In order to remain within the permitted dose equivalent limits for an occupational worker, an individual should NOT receive more than ________ mSv per week (______mrem per week)
    • 1 mSv/wk
    • (100 mrem/wk)
  54. As a general rule, any short lived radionuclide may be disposed of by any normal means after undergoing _______ half lives of decay.
    10 half lives
  55. The recommended annual effective dose equivalent for the skin of a non-occupational worker and the whole body (stochastic) limit for an occupational worker is _____ mSv per year. (____ rem per year)
    • 50 mSv/yr
    • (5 rem/yr)
  56. A sharp drop in lead's ability to attenuate radiation occurs at energies above:
    3 MeV
  57. The fraction of time that a beam is directed at a specific barrier is termed the _______ factor.
    Use factor
  58. The maximum allowable leakage for walls, floors, etc. for a controlled area is _______ cGy per week.
    0.1 cGy/wk
  59. During a radiation treatment, direct patient assistance may be provided if the beam energy is below ______.
    50 keV
  60. The neutron contamination of a photon beam is likely at energies of ________.
    7-20 MeV
  61. The relative amount of radiation that produces late effects is most often substantially _________ (more/less) than the exposure needed to cause the early effect.
    Less
  62. The period of major organogenesis normally occurs during the ___________ of fetal development.
    Second to Eighth
  63. The LD50 for embryonic death following radiation exposure is seen at a dose equivalent of approx _________.
    60 cGy
  64. The dehydration that accompanies the gastrointestinal syndrome is a direct result of radiation damage to _______ cells.
    Stem cells
  65. Radiation induced malformations of the CNS are most common following radiation exposure during:
    Organogenesis
  66. Cells such as the erythrocyte and the spermatozoon that have a specialized function and are in the final stage of their maturation process are termed:
    Differentiated cells
  67. The irradiation of water often results in the development of a poison termed:
    Hydrogen peroxide
  68. The natural rate of childhood malignancies will be expected to double with an absorbed dose of approx ______ to the fetus.
    2 Gy
  69. The biologic response to radiation can be reduced by the use of:
    Sulfhydryl
  70. Radiation damage in radioresistant organs is usually caused by ___________ damage.
    Vasculature damage (indirectly)
  71. The period of time after an acute exposure to radiation in which the effects of the exposure are seen is called the:
    Manifest period
  72. The dose of radiation at which biological response can be noted is termed the:
    Threshold dose
  73. The human fetus is most sensitive to radiation in the _______ trimester.
    First
  74. The first sign of acute radiation syndrome following a large exposure of radiation is usually:
    Nausea
  75. In a linac, the cathode is analogous to the ____________.
    Electron gun
  76. Which is the proper sequence of materials traveled by the x-ray beam of a linac?
    I. Primary collimator
    II. Ion chamber
    III. Flattening filter
    • 3, 2, 1
    • Flattening filter>Ion chamber>Primary collimator
  77. The negative electrode of an x-ray tube is commonly called the cathode or the:
    Filament
  78. The material most suitable for the reduction of electron contamination in megavoltage units is:
    Lucite/tin
  79. The major process by which x-rays are produced in a linac is termed:
    Bremsstrahlung
  80. The dominant factor that influences dose distribution in brachytherapy is the:
    Inverse square law
  81. Point A is located:
    2 cm superior & 2 cm lateral to the cervical os
  82. During electron beam therapies bulging of the isodose lines is most common near the:
    50 and 20 percent curves
  83. The energy range for electrons used in total skin irradiation should have an energy of 2 - __ MeV.
    2 - 9 MeV
  84. For electrons less than 10 MeV, what is the thickness of lead required to obtain less than a 5% transmission?
    3 mm

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