MDCB Practice Set 1 - Test 2
B - answer The development of which of the following conditions is an example of a
stochastic effect of
radiation?
A. organ atrophy
B. second primary
C. pulmonary fibrosis
D. decreased sperm count
A - answer2. When an enface electron beam is used for chest wall irradiation, which of
the following
describes the dose at the interface between the chest wall and lung?
A. decreased due to reduced scatter from the lung
B. decreased due to irregular surface contour effects
C. increased due to an increase in the electron fluence
D. increased due to a larger angle of electron scatter
D - answer3. An averaged ionization chamber reading for a 10 cm x 10 cm electron
applicator is 98.5
and an averaged ionization chamber reading for an electron cut-out in a 6 cm x 10 cm
applicator is 92.4. What is the monitor unit setting if 200 cGy is prescribed to 90% and
the 6 cm
x 10 cm cut-out is utilized? (The output factor for 10 cm x 10 cm is 1 cGy/MU.)
A. 208 MU
B. 217 MU
C. 222 MU
D. 237 MU
C - answer4. Parent and daughter radioactive isotopes are said to be in secular
equilibrium when they:
A. are equal in atomic weight.
B. have the same half-life.
C. have a constant ratio of activity.
D. emit equivalent gamma energies.
D - answer5. To make inhomogeneity corrections in treatment plans based on CT
derived anatomical
information, the TPS:
A. converts CT numbers to Hounsfield units.
B. determines the absorption equivalents.
C. converts to equivalent path lengths.
, D. determines electron densities.
B - answer6. When opposing lateral fields to the pharynx are abutted at midline to an
anterior field to the supraclavicular fossae, overdose in the cord may be avoided by:
A. a 0.5 cm wide by 0.5 cm long midline block placed in the superior portion of the
anterior field.
B. a small block over the cord in the inferior posterior corner of both lateral fields.
C. angling the laterals fields off the cord.
D. angling the supraclavicular field off the cord.
D - answer7. According to the NCRP guidelines #116, the annual equivalent dose limit
for the hands of an
occupational worker in 1 year is:
A. 15 mSv ( 1.5 rem).
B. 50 mSv ( 5.0 rem).
C. 150 mSv (15.0 rem).
D. 500 mSv (50.0 rem).
C - answer8. In photoelectric interactions:
A. chance of occurrence is independent of the atomic number
B. the probability depends on the interaction between a photon and a free radical
C. the entire energy of the incident photon is absorbed by the resulting electron
D. the effect increases as the photon energy increases relative to the binding energy of
the electron
B - answer9. Film badges used for personnel monitoring contain filters that are used to:
A. reduce the dose from low-energy radiations.
B. provide information concerning beam quality.
C. store the absorbed energy for subsequent measurement.
D. filter out naturally occurring radiation.
C - answer10. The most important prognostic factor in breast cancer is the:
A. size of the tumor.
B. age of the patient.
C. status of the axillary nodes.
D. quadrant of origin within the breast.
B - answer11. A dose of 30 Gy in 10 fractions to a depth of 7 cm from a 6 MV single
posterior field using an
isocentric technique at 100 cm source-to-axis distance (SAD). The patient was
incorrectly
treated five times at 100 cm source-to-surface distance (SSD). The approximate dose at
7 cm
after five fractions is:
A. 11.6 Gy.
B. 13.1 Gy.
B - answer The development of which of the following conditions is an example of a
stochastic effect of
radiation?
A. organ atrophy
B. second primary
C. pulmonary fibrosis
D. decreased sperm count
A - answer2. When an enface electron beam is used for chest wall irradiation, which of
the following
describes the dose at the interface between the chest wall and lung?
A. decreased due to reduced scatter from the lung
B. decreased due to irregular surface contour effects
C. increased due to an increase in the electron fluence
D. increased due to a larger angle of electron scatter
D - answer3. An averaged ionization chamber reading for a 10 cm x 10 cm electron
applicator is 98.5
and an averaged ionization chamber reading for an electron cut-out in a 6 cm x 10 cm
applicator is 92.4. What is the monitor unit setting if 200 cGy is prescribed to 90% and
the 6 cm
x 10 cm cut-out is utilized? (The output factor for 10 cm x 10 cm is 1 cGy/MU.)
A. 208 MU
B. 217 MU
C. 222 MU
D. 237 MU
C - answer4. Parent and daughter radioactive isotopes are said to be in secular
equilibrium when they:
A. are equal in atomic weight.
B. have the same half-life.
C. have a constant ratio of activity.
D. emit equivalent gamma energies.
D - answer5. To make inhomogeneity corrections in treatment plans based on CT
derived anatomical
information, the TPS:
A. converts CT numbers to Hounsfield units.
B. determines the absorption equivalents.
C. converts to equivalent path lengths.
, D. determines electron densities.
B - answer6. When opposing lateral fields to the pharynx are abutted at midline to an
anterior field to the supraclavicular fossae, overdose in the cord may be avoided by:
A. a 0.5 cm wide by 0.5 cm long midline block placed in the superior portion of the
anterior field.
B. a small block over the cord in the inferior posterior corner of both lateral fields.
C. angling the laterals fields off the cord.
D. angling the supraclavicular field off the cord.
D - answer7. According to the NCRP guidelines #116, the annual equivalent dose limit
for the hands of an
occupational worker in 1 year is:
A. 15 mSv ( 1.5 rem).
B. 50 mSv ( 5.0 rem).
C. 150 mSv (15.0 rem).
D. 500 mSv (50.0 rem).
C - answer8. In photoelectric interactions:
A. chance of occurrence is independent of the atomic number
B. the probability depends on the interaction between a photon and a free radical
C. the entire energy of the incident photon is absorbed by the resulting electron
D. the effect increases as the photon energy increases relative to the binding energy of
the electron
B - answer9. Film badges used for personnel monitoring contain filters that are used to:
A. reduce the dose from low-energy radiations.
B. provide information concerning beam quality.
C. store the absorbed energy for subsequent measurement.
D. filter out naturally occurring radiation.
C - answer10. The most important prognostic factor in breast cancer is the:
A. size of the tumor.
B. age of the patient.
C. status of the axillary nodes.
D. quadrant of origin within the breast.
B - answer11. A dose of 30 Gy in 10 fractions to a depth of 7 cm from a 6 MV single
posterior field using an
isocentric technique at 100 cm source-to-axis distance (SAD). The patient was
incorrectly
treated five times at 100 cm source-to-surface distance (SSD). The approximate dose at
7 cm
after five fractions is:
A. 11.6 Gy.
B. 13.1 Gy.
