Radiation Protection Q

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Radiation Protection QA
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RAPHEX General Question 2001

• G75 All of the following contribute about
  equally to the average annual dose equivalent
  received by a member of the U.S. population
  EXCEPT
• A. Internal
• B. Terrestrial, other than radon
• C. Medical x-rays
• D. Nuclear medicine
• E. Cosmic

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RAPHEX Answer to 2001 Question G75

• D. Nuclear medicine
• Out of a total of about 3.6 mSv, nuclear
  medicine contributes about 0.14 mSv, and the
  others all contribute about 0.3 to 0.4 mSv each.

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RAPHEX General Question 2002

• G87 The annual average natural background
  radiation dose to members of the public in the
  United States, excluding radon, is approximately
  ___ mrem.
• A. 10
• B. 50
• C. 100
• D. 200
• E. 400

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RAPHEX Answer to 2002 Question G87

• C. 100
• Radon adds another 230 mrem/yr. Man-made
  radiation, mostly diagnostic x-rays, is about 54
  mrem/yr.

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RAPHEX General Question 2003

• G82 The principal hazard from indoor radon
  involves
• A. Whole body dose from gamma rays
• B. Skin dose from betas
• C. Lung dose from alpha emission
• D. Bone dose from deposited radionuclides

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RAPHEX General Question 2001

• G78 The latent period for radiation-induced
  carcinogenesis (solid tumors) is about ____
  years.
• A. 1
• B. 5
• C. 10
• D. 20-30
• E. 40-50

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RAPHEX Answer to 2001 Question G78

• D. The latent period is 20 to 30 years

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RAPHEX General Question 2002

• G89 The currently accepted model of radiation
  dose versus effect used by regulatory agencies to
  determine dose standards is ____.
• A. Linear quadratic
• B. Exponential
• C. Cubic
• D. Linear, threshold
• E. Linear, no threshold

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RAPHEX Answer for 2002 Question G89

• E. Linear, no threshold
• Although there are valid arguments for other
  models in specific situations, the linear, no
  threshold model is the most conservative, and is
  in current use by regulatory agencies.

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RAPHEX General Question 2003

• G86 The radiation protection quantity which has
  been used in attempts to estimate the cancer risk
  from x-ray irradiation of personnel is _____.
• A. Exposure (X)
• B. Air Kerma (K)
• C. Absorbed dose (D)
• D. Dose equivalent (H)
• E. Effective dose (E)

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RAPHEX Answer to 2003 Question G86

• E. Effective dose (E)
• In NCRP Report 116 the Effective dose (E)
  attempts to weight the radiation dose to
  different organs by the relative cancer risk of
  each organ.

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RAPHEX General Question 2001

• G79 Perinatal death (at or around the time of
  birth) is MOST likely to occur as a result of
  irradiation in humans which occurs in the
  gestational period of
• A. Implantation of the embryo
• B. Major organogenesis (21-40 days).
• C. Second trimester
• D. Just before brith (30-36 weeks).

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RAPHEX Answer to 2001 Question G79

• B. Major organogenesis (21-40 days)
• In early organogenesis the organ buds consist of
  a few cells, and the loss of some of these can
  result to a major defect which may not be
  apparent during gestation, but after birth is too
  severe to permit independent life.

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RAPHEX General Question 2003

• G88 According to NCRP there is a negligible
  increase in the risk of adverse effects to the
  fetus, compared with other risks in pregnancy, up
  to a total dose of _____mGy.
• A. 5
• B. 20
• C. 100
• D. 500
• E. 1000

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RAPHEX Answer to 2003 Question G88

• C. 100

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RAPHEX General Question 2001

• G81 Which of the following is true about film
  badges?
• A. Can measure total dose, but cannot distinguish
  between high- and low-energy x-rays.
• B. Can measure exposures of 2 mR
• C. Are insensitive to heat
• D. Are used to determine exposure by measuring
  the optical density of the film
• E. None of the above is true

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RAPHEX Answer to 2001 Question G81

• D. Are used to determine exposure by measuring
  the optical density of the film.
• Film badges cannot measure exposures below 20
  mR. Placing filters over parts of the film
  allows one to estimate the proportion of dose due
  to x-rays in different energy ranges. Heat,
  e.g., exposure to intense sunlight, CAN cause
  film blackening.

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RAPHEX General Question 2002

• G94 According to NCRP Report No. 11, the
  recommended maximum annual dose equivalent for
  radiation workers whole body is ___ mSv and for
  the hands is mSv.
• A. 5, 5
• B. 5, 50
• C. 10, 100
• D. 50, 50
• E. 50, 500

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RAPHEX Answer for 2002 Question G94

• E. 50, 500

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RAPHEX General Question 2003

• G89 The NRC requires personnel to wear a
  radiation monitor if they are likely to receive
  _____ of the annual dose limit
• A. 90
• B 50
• C. 25
• D. 10
• E. 1

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RAPHEX Answer for 2003 Question G89

• D. 10
• Prior to 1994 it was 25, but since this date it
  has been set at 10

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RAPHEX General Question 2001

• G86 When calculating radiation barrier thickness
  requirements, the use factor U refers to
• A. The weekly dose delivered at 1m from the
  radiation source
• B. The fraction of operating time during which
  the area on the other side of the barrier is
  occupied
• C. The fraction of operating time during which
  the radiation is directed towards the barrier
• D. The fraction of the work week during which a
  particular individual is in the area of interest

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RAPHEX Answer to 2001 Question G86

• C. The fraction of operating time during which
  the radiation is directed towards the barrier
• The use factor can be difficult to calculate, so
  standard fractions can be used for the walls and
  floor.

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RAPHEX General Question 2001

• G87 A controlled area is defined as
• A. Any area around a radiation facility where the
  exposure rate is above background
• B. an area that one cannot enter unless one is
  wearing a film badge
• C. An area where workers will not receive more
  than 5 mrem/week
• D. An area where the exposure of workers is under
  the supervision of the Radiation Safety Officer

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RAPHEX Answer for 2001 Question G87

• D. An area where the exposure of workers is under
  the supervision of the Radiation Safety Officer
• Workers can receive up to 100 mrem/week.

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RAPHEX General Question 2002

• G98 When calculating room shielding, the use
  factor U refers to
• A. The weekly dose at the isocenter
• B. The fraction of operating time that the area
  in question is occupied
• C. The fraction of operating time that the beam
  is directed towards the barrier
• D. The fraction of the work week that the machine
  is in operation

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RAPHEX Answer to 2002 Question G98

• C. The fraction of operating time that the beam
  is directed towards the barrier.
• This is hard to estimate exactly, so standard
  fraction are generally used.

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RAPHEX General Question 2002

• G99 When designing shielding for an x-ray
  machine, regulations require that the barrier for
  a fully-occupied non-controlled area must be
  about ____ HVLs thicker than that for a
  controlled area.
• A. 50
• B. 10
• C. 6
• D. 2
• E. 1

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RAPHEX Answer for 2002 Question G99

• C. 6
• The current annual MPDs are 100 mrem for
  non-controlled areas and 5 rem )5000 mrem) for
  controlled areas. This factor of 50 requires
  about 6 HVLs more shielding (26 64)

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RAPHEX General Question 2003

• G94 In the event of a 137Cs dirty bomb
  explosion, regarding the use of potassium iodide
  pills, which of the following is true?
• A. KI should be taken as soon as possible
• B. KI should be taken if the thyroid has the
  potential of receiving a dose greater than 15 rem
• C. A dose of 130 mg per day is suggested for
  adults
• D. KI will offer no protection

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RAPHEX Answer to 2003 Question G94

• D. KI will offer no protection
• Sodium iodide is only used to protect the
  thyroid from the radioactive iodine released in a
  nuclear explosion. 131I has a relatively short
  half-life, and would not be used in a dirty
  bomb.

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RAPHEX General Question 2001

• G91 In general, which of the following detectors
  has the greatest energy dependence for x- and
  gamma rays?
• A. Thin window geiger tube
• B. Air equivalent wall ionization chamber
• C. LiF thermoluminescent dosimeter
• D. NaI scintillator detector

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RAPHEX Answer to 2001 Question G91

• D. NaI scintillator detector
• The high Z of iodine makes it highly sensitive
  to low-energy radiation. This is because of the
  Z dependence of photoelectric interactions.

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RAPHEX General Question 2003

• G95-98 Match the most appropriate instrument to
  the procedure in each question.
• A. Liquid scintillation counter
• B. NaI well counter
• C. Geiger-Mueller (GM) counter
• D. Thermoluminescent dosimeter ( TLD)
• E. Ionization chamber survey meter
• G95 Gamma ray sealed source wipe test
• G96 Contamination survey for 99mTc
• G97 Radiation survey of a diagnostic x-ray
  installation
• G98 Personnel monitoring

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RAPHEX Answer for 2003 Question G95-98

• G95 B. NaI well counter is an efficient device
  for measuring low-level gammas. It can also
  provide energy discrimination
• G96 C. A Gm counter has a fast response and the
  ability to detect low levels of gamma rays
• G97 E. An ionization chamber survey meter is
  capable of accurate x-ray dose rate measurements
  with minimal energy dependence
• G98 D. The small size and relative energy
  independence of TLK make it useful as a personnel
  monitoring device.

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RAPHEX General Question 2001

• G93 The basic consideration when disposing of
  radioactive waste in the sewer system is
• A. Entrance into food and fresh water chain
• B. Contamination of the sewer system
• C. Fish death
• D. Risk to swimmers
• E. Evaporation into the air

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RAPHEX Answer to 2001 Question G93

• A. Entrance into food and fresh water chain
• Very low concentrations of radioactive
  materials, if ingested, can produce high
  localized radiation doses to internal organs.

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RAPHEX General Question 2001

• G94 A unit dose radioisotope is delivered to a
  hospital. The vendor supplies a calibration of
  its activity. Regulations require the hospital
  to do all of the following EXCEPT
• A. Wipe test the package before opening it
• B. Treat the packaging material as low-level
  radioactive waste
• C. Independently verify the activity
• D. Quantify any residual activity left following
  use of the radioisotope
• E. Keep logs of receipt, use, and disposal (or
  storage) of all radioisotopes

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RAPHEX General Question 2002

• G100 After installation of a chest x-ray unit,
  which agency regulates its operation?
• A. NRC
• B. OSHA
• C. HICFA
• D. State

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RAPHEX Answer to 2002 Question G100

• D. State
• Once installed, x-ray units are regulated by the
  state. Mammography units are also regulated by
  the FDA, under MQSA standards. The FDA regulates
  the manufacture and installation of x-ray
  devices, under 21 CFR 1020. The NNRC regulates
  the use of man-made radioactive materials such
  as Co-60 units and brachytherapy sources.

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RAPHEX General Question 2003

• G100 ALARA stands for
• A. As Long As Reasonably Allowable
• B. As Low As Responsibility Attainable
• C. As Low As Reasonably Achievable
• D. As Little As Possible RadioActivity

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RAPHEX Answer to 2003 Question G100

• C. As Low As Reasonably Achievable
• ALARA is a basic tenet of radiation protection.
  Obviously, radiation levels could be reduced to
  negligible levels with huge amounts of shielding
  that would be prohibitively expensive and
  unwieldy. The ALARA concept seeks to strike a
  reasonable balance between safety and
  practicality.

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RAPHEX Diagnostic Question 2003

• D91-92 Match the following maximum permissible
  fluoroscopic tabletop exposure rate with the type
  of II exposure control system (under-table x-ray
  tube)
• A. 5 mR/min
• B.10 mR/min
• C. 5 R/min
• D. 10 R/min
• E. No limit
• D91 Manual control
• D92 Automatic brightness control

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RAPHEX Answer to 2003 Question D91-92

• D91 C. 5 R/min With manual control, where the
  operator sets the mA and the kVp, and it remains
  at those settings, the federal performance
  standard limits table top exposure rate to 5
  R/min for under-0table x-ray tubes.
• D92 D. 10 R/min With auto-brightness control
  systems, the table top exposure rate can be 10
  R/min. The philosophy is that in this mode it is
  allowable to go higher exposure rates for the
  thick patients.

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RAPHEX Diagnostic Question 2003

• D93 In 131I therapy for thyroid cancer, the
  whole body clearance curve is commonly plotted
  versus time. The radiation absorbed dose to the
  patient is proportional to the ____.
• A. Administered activity of I-131
• B. Administered activity per unit body surface
  area
• C. Administered activity per unit body weight
• D. Peak counts in the clearance curve
• E. Area under the clearance curve normalized to
  per unit body weight

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RAPHEX Answer to 2003 Question D93

• E. Area under the clearance curve normalized to
  per unit body weight.
• The absorbed dose depends on the patient
  specific clearance kinetics. The same activity
  administered to two different patients of the
  same weight could result in different absorbed
  doses, if they metabolized and cleared the 131I
  at different rates.

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RAPHEX Diagnostic Question 2003

• D95 Well-collimated AP and lateral chest
  radiographs are taken on a patient. She later
  discovers that she was pregnant at the time of
  the study. The expected fetal radiation dose
  would be about ___ mSv.
• A. 0.005
• B. 0.5
• C. 5
• D. 50
• E. 100

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RAPHEX Answer to 2003 Question D95

• A. 0.005
• According to HEW 9FDA) 76-8231 the embryo would
  receive about 0.002 to 0.004 of the primary beam.
  Since AP chest radiographs usually deliver less
  than 30 mR at the skin surface, and the LAT is
  about 2.5 times greater, the dose to the fetus
  would be less than 0.004 X (30 X 3.5) 0.42 mR
  or 0.0042 mGy, which is about 0.0042

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RAPHEX Diagnostic Question 2002

• D91 In nuclear medicine studies, critical organ
  doses are usually about ___ Gy.
• A. 0.005
• B. 0.05
• C. 0.5
• D. 5
• E. 50

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RAPHEX Answer to 2002 Question D91

• B. 0.05
• 0.05 Gy 5 rad

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RAPHEX Diagnostic Question 2002

• D92 The typical amount of lead in lead aprons
  used in fluoroscopy rooms is about ___.
• A. 10 um
• B. 0.1 mm
• C. 0.5 mm
• D. 0.5 cm
• E. 1.0 cm

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RAPHEX Answer to 2002 Question D92

• C. 0.5 mm
• 0.5 mm Pb will reduce the x-ray intensity by 95
  to 99, depending on the kVp.

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RAPHEX Diagnostic Question 2002

• D93 During a typical fluoroscopy procedure a
  radiologist wearing a lead apron and no
  protective eyewear receives a uniform whole body
  exposure of 20 mR. How many similar procedures
  can the raiologist perform in one week?
• A. 5
• B. 15
• C. 50
• D.100
• E. 250

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RAPHEX Answer to 2002 Question D93

• B. 15
• The NCRP recommended doses are 5 rem/yr to the
  eyes. This is equivalent to 100 mrem/week whole
  body and 300 mrem/week to the eyes. Since the
  lead apron will stop 95 of the whole body dose,
  the eye dose is limiting facotr, and will reach
  300 mrem after fifteen 20 mR procdures.

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RAPHEX Diagnostic Question 2001

• Match the exposure with the appropriate exam
• A. 15mR
• B. 30mR
• C. 60mR
• D. 5R
• E. 10R
• D85 CT head scan ESE
• D86 Lateral chest ESE

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RAPHEX Answer to 2001 Question D85-86

• D85 D. 5R
• 4 to 6 R are typical values for a head scan
  series
• D86 C. 60mR
• A lateral chest ESE is typically 50 to 80 mR.