Radiation Therapy Equipment and QA (Mosby Ch 6 Questions)

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jaxkaty5437
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Radiation Therapy Equipment and QA (Mosby Ch 6 Questions)
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2014-03-08 19:35:20
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Radiation Therapy
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RTT Board Review,Mosby Board Review Questions
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Radiation Therapy Equipment and QA(Mosby Ch 6 Questions)
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  1. *The protective housing around the cobalt source in the cobalt machine should allow transmission of ____% of the output.
    0.1 %
  2. *The source of electrons in the linac is the:
    electron gun
  3. *Trimmer bars are attached to the collimator of the cobalt machine to reduce the effect of the:
    penumbra
  4. *Calculate the width of the penumbra with an 80 cm SAD cobalt unit. Source diameter is 3.0 cm and the SDD is 40 cm. Treatment SSD is 75 cm.
    Penumbra=3(75+5-40)/40=3 cm
  5. *Calculate the width of the penumbra with an 80 cm SAD cobalt unit.
    Source diameter is 2.0 cm and the SDD is 40 cm. Treatment SSD is 77 cm.
    penumbra=2(77+3-40)/40=2 cm
  6. *The purpose of the flattening filter in the linac is to:
    Evenly distribute the energy of the photon beam across a specified area
  7. *What is the purpose of the magnetron and klystron in the linac?
    They produce microwaves to accelerate electrons
  8. *Trimmer bars attached to the cobalt collimator system should not be allowed closer than 15 cm from the patients skin. Why?
    The trimmer bars and radiation produces secondary scatter. 15 cm is required to reduce the scatter to the patient.
  9. As the distance from the source increases, the penumbra_____.
    increases
  10. *As SSD increases, the penumbra_____.
    decreases
  11. *The target in the linac is typically made of ___.
    tungsten
  12. *Why do we use tissue compensators and wedges instead of bolus to compensate for irregular contours?
    Because they preserve skin-sparing
  13. *Which radioisotope is used for bone mets?
    Strontium-89
  14. *The field light on the linac is intended to represent the:
    area of radiation exposure
  15. *The scattering foil is used in the ___beam mode.
    electron
  16. *The cyclotron may produce____beams.
    proton
  17. *Energy range of early generation superficial therapy machines:
    50-150 kV
  18. *The linc generates a high-energy photon or electron beam by:
    accelerating charged particles in a linear path
  19. *Geometric penumbra , characterictic of the cobalt beam increases with:
    Increasing source size and increasing distance from the source
  20. Half-life of Radium-226
    1622 years
  21. *Half-life of Iodine-125
    60 days
  22. Half-life of Cesium-137
    30 years
  23. *Half-life of Gold-198
    2.7 days
  24. *the Fletcher's Suite application is an example of:
    intracavitary LDR brachytherapy
  25. *The important QA test(s) associated with the light field are(circle all that apply)
    1)field size accuracy
    2)beam output
    3)light and radiation field coincidence
    • 1)field size accuracy
    • 2)beam output
    • 3)light and radiation field coincidence
  26. *The target to patient skin distance is measured using:
    An ODI indicator
  27. *The tolerance for the localizing laser and ODI is:
    2 mm
  28. *The constancy of the linac, when compared with benchmark values established during commissioning must be within:
    3%
  29. Output constancy for electron and photons must be checked____.
    DAILY
  30. *The x-ray beam in a linac must exhibit flatness within about:
    2%
  31. *Which out daily on the of the following checks must be carried out on the cobalt machine:
    1)function of the radiation room monitor
    2)door inerlocks
    3)beam output
    4)timer error
    • 1)function of the radiation room monitor
    • 2)door inerlocks
    • 3)beam output
    • 4)timer error
  32. *Full calibration and overhaul of treatment equipment must be carried out_____.
    annually
  33. *Localizing lasers on simulators must be within ____of isocenter.
    2mm
  34. *Microwave power is directed towards the accelerator guide:
    Waveguide
  35. *Electrons are produced by the
    electron gun
  36. *At the end of acceleration, high energy electrons are focused toward the collimator by the _____.
    bending magnet
  37. *The electron beam is spread out uniformly by the______.
    scattering foil
  38. *Monitors radiation output:
    ion chamber
  39. *Produces high voltage and high power electrical pulses to generate microwave power:
    modulator
  40. *Microwaves travel through these components and are prevented from reflecting backward:
    waveguide, radiofrequency driver
  41. *To check for accuracy of gantry digital readouts, one could use:
    a spirit level at 45-degree angle increments
  42. *The linear scales on the treatment table are useful for:
    • daily treatment setup
    • translation of patient positions from simulation to treatment
  43. *which of the following verifies the accuracy of the treatment dose delivery:
    backup timer, radiation off switch, door interlock, and emergency off switch
  44. *The process for testing a new linac against manufacturer's specifications is called:
    acceptance testing
  45. *Gantry and collimator indicators should be within ____degree(s).
    1
  46. *All of the following might account for a beam's flatness deviating outside of specifications, except for:
    1)flattening filter shift
    2)target position shift
    3)Incorrect mirror angulation
    4)Fluctuation of current
    • 1)flattening filter shift
    • 2)target position shift
    • 3)Incorrect mirror angulation
    • 4)Fluctuation of current
  47. *A mechanical distance indicator is used to verify:
    Accuracy of the optical distance indicator
  48. *Which of the following has the shortest half-life?
    1)Cesium-137
    2)Gold-198
    3)Iridium-192
    4)Radon-222
    2)Gold-198
  49. *Superficial treatment machines used short treatment distances because:
    Percent dose depth falls of rapidly
  50. *T/F
    Increasing the beam on time can increase the effective energy of the photon beam.
    FALSE
  51. T/F
    Increasing the tube potential can increase the effective energy of the photon beam.
    TRUE
  52. *The machine that consists of short metallic cylinders divided into two D-Shaped cavities is known as the:
    cyclotron

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