Radiation Therapy 2009-2010 Practice Test B - Dosimetry Equations

7 Questions | Total Attempts: 1047

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Radiation Therapy 2009-2010 Practice Test B Created by Matt. Some of the multiple choice are actually "Multiple Answers", keep that in mind when reading questions. Enter "whole" number means, a "whole" number, not a decimal, or a fraction. It does not mean, Eneter the "entire" number.


Questions and Answers
  • 1. 
    The film for and SSD treatment on a linear accelerator is taken at 133 cm.  What is the magnification factor?
    • A. 

      1.33 cm

    • B. 

      1.53 cm

  • 2. 
    A patient is simulated to receive a treatment to cover a tumor volume plus 1 cm on each side.  The tumor is 3.5 cm wide and the depth of 4 cm.  What will be the necessary field width at the skin surface, using a linear accelerator with the isocentric setup?
    • A. 

      5.28 CM

    • B. 

      6.31 CM

    • C. 

      4.45 CM

    • D. 

      6.67 CM

    • E. 

      8.0 CM

  • 3. 
    What is the field size on a film if the collimator setting is 7X19 CM, and the magnification factor is 1.33X?Choose closest answer.
    • A. 

      8x15 cm

    • B. 

      10x10 cm

    • C. 

      9x25 cm

    • D. 

      11x25 cm

    • E. 

      8.99x26 cm

  • 4. 
    The dose at isocenter for a field is 75 cGy per fraction.  At a depth of 6 CM, using a 6 Mev beam, 10X10 CM collimator, the TMR is 0.899.  The dose at a depth of maximum build up is 83.4 cGy  each time the isocenter gets 75 cGy.  If the patient is to get 2625 cGy from this field, what is the total dose at d/max?(Enter whole number) 
  • 5. 
    A patient is treated with parallel opposed portal.  The isocenter is it midline.  The fields are equally weighted.  The total dose is 5760 cGy, and the daily dose per port is 90 cGy.  How many daily treatments will the patient received? (Enter whole number)
  • 6. 
    A tumor is to receive 6300 cGy in 42 fractions.  What is the dose per fraction?______cGy/Fraction(Enter whole number)
  • 7. 
    The dose rate on a linac machine is 102.4 cGy/Min at 100 cm.  What is the dose rate at 85.5 cm?_______cGy/Min(Enter whole number)
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