RAPHEX CORRECT EXAMS QUESTIONS AND
ANSWERS SURE A+
✔✔What is the major advantage of using kV cone-beam CT rather than gantry mounted
kV orthogonal planar radiographs?
A. Image acquisition and registration is faster.
B. Images can be acquired at large couch angles.
C. Images can be aligned to a soft tissue target.
D. All of the above are true.
E. None of the above is true. - ✔✔C. Images can be aligned to a soft tissue target.
✔✔_________would be expected to have the smallest amount of modulation in the
fluence.
A. An IMRT plan to a target overlapping with a previously irradiated targe
B. An MRI prostate plan for a patient with bilateral hip prostheses.
C. Single brain metastasis treated with dynamic conformal arcs (DCA)
D. Paraspinal SBRT treated with VMAT
E. Conventionally fractionated VMAT head and neck irradiation - ✔✔C. Single brain
metastasis treated with dynamic conformal arcs (DCA).
✔✔The gamma index—used for evaluation of how well a measured dose distribution
matches a corresponding predicted dose distribution and often used in the evaluation of
IMRT QA-is a composite number that combines which two of the following four metrics?
1. distance to agreement between measured and predicted isodose lines
2. difference between the predicted and measured dose at each corresponding point in
the two dose distributions
3. difference between the global minimum dose in each dose distribution
4. difference between the global maximum dose in each dose distribution
A. 1,2
B. 1,3
C. 1,4
D. 2,3
, E. 3, 4 - ✔✔A. When comparing a measured and a predicted dose distribution, the
distributions can be offset
spatially or offset in terms of dose magnitude, and likely are slightly offset both spatially
and
in terms of dose magnitude. Therefore, a composite number that attempts to quantify
both
spatial offset and dose difference is used when evaluating measured and predicted
dose
distributions
✔✔You cannot verify the profile across an IMRT field using a single ionization chamber
at a fixed position in a 3D water tank because the
A. typical IMRT dose rate is too high
B. typical MLC openings are too small
C. beam quality in an IMRT field is different from that in an open field
D. IMRT dose rate to any point in the field is time-dependent
E. None of the above is true. - ✔✔D. The IMRT field would have to be delivered once
for each measurement point, which is too
time consuming (a detector array inside the tank would work).
✔✔Which of the following tests or measurements is NOT part of treatment planning
system
commissioning for IMRT?
A. end-to-end test
B. Winston-Lutz test
C. MLC transmission measurement
D. CT-number to electron density measurement
E. Beam profile measurements - ✔✔B. Winston-Lutz test. The MLC, CT number vs.
electron density curve, and beam profiles all need to be modeled and verified. The
Winston-Lutz test is designed to measure the alignment between the mechanical
axes of the gantry, collimator, and couch. Although this is an important test, especially
for SRS
treatments, it is not part of treatment planning system commissioning.
✔✔Which detector can be used for small-field data collection required for IMRT field
sizes ≥ 3x3 cm??
A. G-M counter
B. Large-volume ion chamber
C. well chamber
D. diode
E. 0.6-cc Farmer chamber - ✔✔D. diode
✔✔According to the AAPM TG-43 formalism, the conversion of air kerma to dose in
water is
performed by
ANSWERS SURE A+
✔✔What is the major advantage of using kV cone-beam CT rather than gantry mounted
kV orthogonal planar radiographs?
A. Image acquisition and registration is faster.
B. Images can be acquired at large couch angles.
C. Images can be aligned to a soft tissue target.
D. All of the above are true.
E. None of the above is true. - ✔✔C. Images can be aligned to a soft tissue target.
✔✔_________would be expected to have the smallest amount of modulation in the
fluence.
A. An IMRT plan to a target overlapping with a previously irradiated targe
B. An MRI prostate plan for a patient with bilateral hip prostheses.
C. Single brain metastasis treated with dynamic conformal arcs (DCA)
D. Paraspinal SBRT treated with VMAT
E. Conventionally fractionated VMAT head and neck irradiation - ✔✔C. Single brain
metastasis treated with dynamic conformal arcs (DCA).
✔✔The gamma index—used for evaluation of how well a measured dose distribution
matches a corresponding predicted dose distribution and often used in the evaluation of
IMRT QA-is a composite number that combines which two of the following four metrics?
1. distance to agreement between measured and predicted isodose lines
2. difference between the predicted and measured dose at each corresponding point in
the two dose distributions
3. difference between the global minimum dose in each dose distribution
4. difference between the global maximum dose in each dose distribution
A. 1,2
B. 1,3
C. 1,4
D. 2,3
, E. 3, 4 - ✔✔A. When comparing a measured and a predicted dose distribution, the
distributions can be offset
spatially or offset in terms of dose magnitude, and likely are slightly offset both spatially
and
in terms of dose magnitude. Therefore, a composite number that attempts to quantify
both
spatial offset and dose difference is used when evaluating measured and predicted
dose
distributions
✔✔You cannot verify the profile across an IMRT field using a single ionization chamber
at a fixed position in a 3D water tank because the
A. typical IMRT dose rate is too high
B. typical MLC openings are too small
C. beam quality in an IMRT field is different from that in an open field
D. IMRT dose rate to any point in the field is time-dependent
E. None of the above is true. - ✔✔D. The IMRT field would have to be delivered once
for each measurement point, which is too
time consuming (a detector array inside the tank would work).
✔✔Which of the following tests or measurements is NOT part of treatment planning
system
commissioning for IMRT?
A. end-to-end test
B. Winston-Lutz test
C. MLC transmission measurement
D. CT-number to electron density measurement
E. Beam profile measurements - ✔✔B. Winston-Lutz test. The MLC, CT number vs.
electron density curve, and beam profiles all need to be modeled and verified. The
Winston-Lutz test is designed to measure the alignment between the mechanical
axes of the gantry, collimator, and couch. Although this is an important test, especially
for SRS
treatments, it is not part of treatment planning system commissioning.
✔✔Which detector can be used for small-field data collection required for IMRT field
sizes ≥ 3x3 cm??
A. G-M counter
B. Large-volume ion chamber
C. well chamber
D. diode
E. 0.6-cc Farmer chamber - ✔✔D. diode
✔✔According to the AAPM TG-43 formalism, the conversion of air kerma to dose in
water is
performed by
