RAPHEX ACTUAL FINALS QUESTIONS AND
ANSWERS SURE A+
✔✔If the energy (in the previous question) was changed from 15 MV to 6 MV, the MU
would:
A. increase
B. decrease
C. remain the same
D. There is not enough information given to answer the question. - ✔✔A. Since 6-MV x-
rays are less penetrating, more MU would be necessary to deliver the same dose
to midplane depth. In other words, TMR decreases as the energy decreases.
✔✔Which of the following interactions are possible for a 10-MeV electron beam
traversing water?
A. ionization of water molecules
B. photoelectric effect
C. pair production
D. All of the above are true.
E. None of the above is true. - ✔✔A. ionization of water molecules. Electrons are
directly ionizing particles that can interact with a water medium via excitation, ionization,
and bremsstrahlung. Photoelectric effect and pair production are interactions between
photons and a medium.
✔✔Which of the following is FALSE regarding the effective SSD of an electron beam?
A. It is the distance from the scattering foil position to the patient surface.
B. It gives the correct inverse square law relationship for the change in output with
distance.
C. It changes with energy.
D. It changes with cone size.
E. It can be determined based on phantom measurement. - ✔✔A. It is the distance from
the scattering foil position to the patient surface.
, ✔✔According to the AAPM Task Group 142 report, al of the following are daily QA
checks except:
A. X-ray output constancy
B. light field/radiation field coincidence
C. room lasers
D. door interlock
E. collimator size indicator - ✔✔B. light field/radiation field coincidence
✔✔According to AAPM Task Group 142, the x-ray output constancy measured by a
physicist during the monthly QA check should be within of the baseline value.
A. 0.5%
B. 1%
C. 2%
D. 3%
E. 5% - ✔✔C. 2%. Daily constancy is 3%.
✔✔The leak test of a sealed source must be performed at intervals not to exceed___,
and the source is considered to be leaky if a presence of ______or more of removable
contamination is measured.
A. 3 months; 0.05 uCi
B. 3 months; 0.005 uCi
C. 6 months; 0.05 uCi
D. 6 months; 0.005 uCi
E. 6 months; 0.0005 uCi - ✔✔D. According to NRC 10 CFR part 39, the wipe test of
sealed source must be performed using a leak test kit or method approved by the
Commission/Agreement State. The wipe sample must be taken from the nearest
accessible point to the sealed source where contamination might accumulate/must be
analyzed for radioactive contamination. The analysis must be capable of detecting the
presence of 185 Bq (0.005 microcuries) of radioactive material on the test sample. Each
sealed source except an energy compensation source (ECS)-must be tested at intervals
not to exceed 6 months.
✔✔The fraction of ultrasound waves reflected at the interface between two different
media depends on the difference in the _________ and the ______ between the two
media.
A. density; atomic number
B. density; speed of sound
C. density; temperature
D. atomic number: speed of sound
E. atomic number; temperature - ✔✔B. density; speed of sound. Ultrasound wave
reflections or echoes are caused by variations in acoustic impedance of
materials on opposite sides of the interfaces. The acoustic impedance (Z) of a medium
is defined as the product of the density of the medium and the speed of ultrasound
waves in the medium.
ANSWERS SURE A+
✔✔If the energy (in the previous question) was changed from 15 MV to 6 MV, the MU
would:
A. increase
B. decrease
C. remain the same
D. There is not enough information given to answer the question. - ✔✔A. Since 6-MV x-
rays are less penetrating, more MU would be necessary to deliver the same dose
to midplane depth. In other words, TMR decreases as the energy decreases.
✔✔Which of the following interactions are possible for a 10-MeV electron beam
traversing water?
A. ionization of water molecules
B. photoelectric effect
C. pair production
D. All of the above are true.
E. None of the above is true. - ✔✔A. ionization of water molecules. Electrons are
directly ionizing particles that can interact with a water medium via excitation, ionization,
and bremsstrahlung. Photoelectric effect and pair production are interactions between
photons and a medium.
✔✔Which of the following is FALSE regarding the effective SSD of an electron beam?
A. It is the distance from the scattering foil position to the patient surface.
B. It gives the correct inverse square law relationship for the change in output with
distance.
C. It changes with energy.
D. It changes with cone size.
E. It can be determined based on phantom measurement. - ✔✔A. It is the distance from
the scattering foil position to the patient surface.
, ✔✔According to the AAPM Task Group 142 report, al of the following are daily QA
checks except:
A. X-ray output constancy
B. light field/radiation field coincidence
C. room lasers
D. door interlock
E. collimator size indicator - ✔✔B. light field/radiation field coincidence
✔✔According to AAPM Task Group 142, the x-ray output constancy measured by a
physicist during the monthly QA check should be within of the baseline value.
A. 0.5%
B. 1%
C. 2%
D. 3%
E. 5% - ✔✔C. 2%. Daily constancy is 3%.
✔✔The leak test of a sealed source must be performed at intervals not to exceed___,
and the source is considered to be leaky if a presence of ______or more of removable
contamination is measured.
A. 3 months; 0.05 uCi
B. 3 months; 0.005 uCi
C. 6 months; 0.05 uCi
D. 6 months; 0.005 uCi
E. 6 months; 0.0005 uCi - ✔✔D. According to NRC 10 CFR part 39, the wipe test of
sealed source must be performed using a leak test kit or method approved by the
Commission/Agreement State. The wipe sample must be taken from the nearest
accessible point to the sealed source where contamination might accumulate/must be
analyzed for radioactive contamination. The analysis must be capable of detecting the
presence of 185 Bq (0.005 microcuries) of radioactive material on the test sample. Each
sealed source except an energy compensation source (ECS)-must be tested at intervals
not to exceed 6 months.
✔✔The fraction of ultrasound waves reflected at the interface between two different
media depends on the difference in the _________ and the ______ between the two
media.
A. density; atomic number
B. density; speed of sound
C. density; temperature
D. atomic number: speed of sound
E. atomic number; temperature - ✔✔B. density; speed of sound. Ultrasound wave
reflections or echoes are caused by variations in acoustic impedance of
materials on opposite sides of the interfaces. The acoustic impedance (Z) of a medium
is defined as the product of the density of the medium and the speed of ultrasound
waves in the medium.
