Diagnostic And Nuclear Medicine Radiation Shielding - Session 2

15 Questions | Total Attempts: 261

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Nuclear Medicine Quizzes & Trivia

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Questions and Answers
  • 1. 
    The walls of a mammography suite usually require
    • A. 

      At least 1/32" lead

    • B. 

      At least 1/16" lead

    • C. 

      At least two sheets of gypsum wallboard

    • D. 

      No shielding

  • 2. 
    Generally, walls and doors located behind the mammography patient will not require additional shielding
    • A. 

      True

    • B. 

      False

  • 3. 
    For a typical 4 view mammographic procedure (with a Mo anode/Mo filter x-ray system), the kerma generated by secondary radiation at 1 m distance from the unit is not greater than
    • A. 

      0.010 mGy

    • B. 

      0.026 mGy

    • C. 

      0.031 mGy

    • D. 

      0.036 mGy

  • 4. 
    We wish to shield the control booth wall of a radiographic room using the NT/Pd2 method of NCRP-147. This method is limited since it only considers primary radiation from x-ray beams directed at the control booth wall.
    • A. 

      True

    • B. 

      False

  • 5. 
    We wish to shield the door of a radiographic room (opening to an uncontrolled corridor) using the NT/Pd2 method of NCRP-147. The room will image 125 patients per week. If this door is only exposed by secondary radiation, and the shortest distance from a scatter source is 3.5 m from the radiographic table, the value of NT/Pd2 to use in the charts is:
    1. 63.8 mGy-1 m-2
    2. 125.3 mGy-1 m-2
    3. 199.2 mGy-1 m-2
    4. 528.3 mGy-1 m-2
    • A. 

      The answer is a

    • B. 

      The answer is b

    • C. 

      The answer is c

    • D. 

      The answer is d

  • 6. 
    We wish to shield the wall between a radiographic room and an office using the NT/Pd2 method of NCRP-147. The wall is only exposed by secondary radiation. For this barrier we calculate a NT/Pd2 value of 1000  mGy-1 m-2. The thickness of lead shielding required for this wall is
    • A. 

      0.47 mm

    • B. 

      0.78 mm

    • C. 

      0.98 mm

    • D. 

      1.58 mm

  • 7. 
    CT scanners generate
    • A. 

      A trivial amount of radiation, and so typically need little shielding

    • B. 

      A significant amount of secondary radiation against which we will need shielding

    • C. 

      A significant amount of primary radiation which may penetrate the gantry and expose the environs of the scanner suite

    • D. 

      A significant magnetic field whose strength outside the scanner room may effect pacemaker patients

  • 8. 
    We wish to shield the control booth window of a radiographic room using the NT/Pd2 method of NCRP-147.  The method specifies a minimal acceptable concrete barrier thickness of 10 mm. This level of protection is also provided by ___ mm of plate glass.
    • A. 

      8.3 mm

    • B. 

      12 mm

    • C. 

      18 mm

    • D. 

      20 mm

  • 9. 
    The scatter radiation intensity generated by a CT scanner increases with increasing
    • A. 

      KVp

    • B. 

      MA

    • C. 

      X-ray beam width

    • D. 

      Scan time

    • E. 

      All of the Above

  • 10. 
    A CT manufacturer's isoexposure scatter curves indicate 1.3 microGy per scan at a distance of 2.3 m from gantry isocenter. What is the kerma per scan at a distance of 3.4 m from isocenter?
    • A. 

      0.59 microGy

    • B. 

      0.88 microGy

    • C. 

      1.92 microGy

    • D. 

      2.84 microGy

  • 11. 
    According to the assumptions in NCRP-147, the average DLP for a head scan is 1,200 mGyAcm. Therefore, the unshielded kerma 1 m from isocenter from a typical head scan patient is _____ mGy.       a.9H10-5       b.0.108       c. 0.36       d. 1,200
    • A. 

      The answer is a

    • B. 

      The answer is b

    • C. 

      The answer is c

    • D. 

      The answer is d

  • 12. 
    We wish to specify the barrier thickness in the wall of a CT scan suite. An uncontrolled corridor exists beyond the wall. With no shielding, a weekly kerma of 6.8 mGy is predicted in the corridor. For an acceptable barrier, the transmission through the wall should not exceed _____.
    • A. 

      0.00294

    • B. 

      0.0147

    • C. 

      0.0235

    • D. 

      0.0588

  • 13. 
    Another wall of this CT scanner suite abuts an uncontrolled, fully occupied office.  With no shielding, a weekly kerma of 8.6 mGy is predicted in the office. What thickness of Pb in the wall is needed to adequately shield this office?
    • A. 

      0.79 mm Pb

    • B. 

      1.0 mm Pb

    • C. 

      1.59 mm Pb

    • D. 

      1.73 mm Pb

  • 14. 
    A CT scanner is operated at 120 kVp. At this potential the alpha fitting parameters to the Archer equation for CT x-rays are 2.246 mm-1 and 0.0383 mm-1 for Pb and concrete, respectively. The shielding calculation specifies a ceiling requirement of 152 mm concrete. Unfortunately, the concrete thickness in the ceiling is only 102 mm. How much Pb should be added to this ceiling?
    • A. 

      0.32 mm

    • B. 

      0.45 mm

    • C. 

      0.85 mm

    • D. 

      1.2 mm

  • 15. 
    For the foreseeable future, the doors of all mammography rooms will be satisfactorily shielded using solid core wood doors.
    • A. 

      True

    • B. 

      False

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