MDCB Practice Test 2026, 2025, 2014
Multiple Choice
Which one of the following DVH results for a pancreatic treatment plan of conventional
fractionation meets QUANTEC recommended dose tolerances? - answer25% of the
stomach will receive 45Gy.
Which of the following is TRUE regarding clinical electron beams? - answerHigh energy
electrons lose energy at a rate of approximately 2 MeV per cm of water or soft tissue.
What factors are instrumental in determining the dose uniformity in equally weighted
parallel opposed beams? - answerbeam energy, tissue inhomogeneity and patient
thickness
Which of the following computer algorithms can most accurately account for the dose
calculation uncertainty in the interface region between inhomogeneous materials for
photon calculations?
*used most often to create uniform dose with photons - answerMonte Carlo method
An IMRT technique in which the patient is treated slice by slice by intensity-modulated
beams in a manner analogous to CT imaging is called: - answerhelical LINAC
Which of the following is the best thermal neutron absorber? - answerboronated
polyethylene
Relative skin dose from a megavoltage photon beam is increased by which of the
following? - answerincreasing the thickness bolus material used
The risk of symptomatic radiation pneumonitis is:
*more "symptoms" with chemo - answerincreased if certain chemotherapy agents are
used.
DVHs can confirm which of the following? - answerThe normal tissue tolerances are
respected.
When comparing identical (IMRT) treatment plans, one delivered with sliding window
and the other delivered with step-and-shoot, the sliding window treatment will most
likely have which of the following? total MU / total tx time - answerhigher / shorter
What will result if a photon field abuts an electron field at the skin surface? -
answerphoton side hot spot, electron side cold spot
,Isocentric, parallel opposed oblique fields with unequal depths may result in: - answera
plan with isodose lines that are similar to a plan with equal depths and unequally
weighted beams.
What can cause increased skin dose in IMRT for prostate cancer? - answercarbon fiber
couch
Which of the following processes best explains how a radiation beam is delivered during
stepand-shoot IMRT? - answerRadiation is only delivered while the MLC is stopped.
Characteristics of MLC, in current medical LINACs, include which of the following: -
answer"scalloped" isodose curves in the penumbra region.
Which of the following can be determined from the V20 obtained from a DVH for both
lungs? - answervolume of both lungs receiving 20 gy
To eliminate the divergence into the lung of both fields when planning an intact breast
treatment using isocentric medial and lateral opposed fields, it would be necessary to: -
answermatch the posterior diverging beam edges.
Physical penumbra width is defined as the lateral distance between which two isodose
curves at the level of dmax?
*physical penumbra = geometric & transmission penumbra, so lateral distance is wide -
answer20% and 80%
Two adjacent electron fields are to be used to treat a post-mastectomy chestwall. The
radiation oncologist has expressed concern that a cold spot at the surface be avoided.
Appropriate techniques include which of the following? - answerMove the junction
several times during the treatment course.
The minimum nominal distance a tissue compensator should be placed from the skin
surface without affecting the skin sparing effect is: - answer20.0 cm.
When treating with electrons typical X-ray contamination dose to a patient ranges from
approximately: - answer0.5% to 5%
Rounded ends on the leaves of a multi-leaf collimator are used to: - answerachieve a
constant penumbra as field size varies.
Which of the following statements regarding geometric penumbra is TRUE? -
answerThe penumbra increases as the distance from the source increases, all other
factors being equal.
, Which calculation method independently calculates the primary and the scattered
components of dose at a point in the calculation volume?
*calcs 2 components. 2 things can be "superimposed" on one another -
answerConvolution superposition
Which of the following statements is CORRECT regarding the concept of equivalent
squares in dose calculation? - answerA rectangular field is equivalent to a square field if
they have the same Area/Perimeter ratio.
Computerized MU calculations for delivery of the prescribed dose to a point near a
block need special care for which of the following reasons? - answerA steep dose
gradient exists near the block.
When an isocentric (SAD) technique is used in place of an SSD technique (both beams
treated at 100SSD) to deliver the same midpoint dose to a patient with two parallel
opposed fields, the: - answerratio of maximum dose to midpoint dose is increased
The number of atoms decaying per second is expressed in terms of their:
*as they decay, their "A" becomes lower than "Ao" - answeractivity.
Based on NCRP recommendations, which of the following is a guideline regarding
pregnancy and radiation exposure? - answerPregnant medical radiation workers can be
considered occupationally exposed individuals.
The dose response model applied in establishing dose limits for occupational workers is
the: - answerlinear no-threshold model.
Which of the following statements is/are TRUE concerning radiation warning signs? -
answerThe terms "Caution" or "Danger" may be used in "High Radiation Areas".
The installation of any new treatment planning system requires the acceptance testing
of which of the following? - answersoftware
At what frequency should treatment chart checks be accomplished for each patient? -
answerweekly
According to AAPM TG Report #142 standards, what is the minimum frequency for
checking the door interlock? - answerdaily
What is the standard file format for network communication that allows handling, storing,
transferring and printing of medical imaging data? - answerDICOM
The force that holds the nucleus together is: - answerstrong nuclear
Multiple Choice
Which one of the following DVH results for a pancreatic treatment plan of conventional
fractionation meets QUANTEC recommended dose tolerances? - answer25% of the
stomach will receive 45Gy.
Which of the following is TRUE regarding clinical electron beams? - answerHigh energy
electrons lose energy at a rate of approximately 2 MeV per cm of water or soft tissue.
What factors are instrumental in determining the dose uniformity in equally weighted
parallel opposed beams? - answerbeam energy, tissue inhomogeneity and patient
thickness
Which of the following computer algorithms can most accurately account for the dose
calculation uncertainty in the interface region between inhomogeneous materials for
photon calculations?
*used most often to create uniform dose with photons - answerMonte Carlo method
An IMRT technique in which the patient is treated slice by slice by intensity-modulated
beams in a manner analogous to CT imaging is called: - answerhelical LINAC
Which of the following is the best thermal neutron absorber? - answerboronated
polyethylene
Relative skin dose from a megavoltage photon beam is increased by which of the
following? - answerincreasing the thickness bolus material used
The risk of symptomatic radiation pneumonitis is:
*more "symptoms" with chemo - answerincreased if certain chemotherapy agents are
used.
DVHs can confirm which of the following? - answerThe normal tissue tolerances are
respected.
When comparing identical (IMRT) treatment plans, one delivered with sliding window
and the other delivered with step-and-shoot, the sliding window treatment will most
likely have which of the following? total MU / total tx time - answerhigher / shorter
What will result if a photon field abuts an electron field at the skin surface? -
answerphoton side hot spot, electron side cold spot
,Isocentric, parallel opposed oblique fields with unequal depths may result in: - answera
plan with isodose lines that are similar to a plan with equal depths and unequally
weighted beams.
What can cause increased skin dose in IMRT for prostate cancer? - answercarbon fiber
couch
Which of the following processes best explains how a radiation beam is delivered during
stepand-shoot IMRT? - answerRadiation is only delivered while the MLC is stopped.
Characteristics of MLC, in current medical LINACs, include which of the following: -
answer"scalloped" isodose curves in the penumbra region.
Which of the following can be determined from the V20 obtained from a DVH for both
lungs? - answervolume of both lungs receiving 20 gy
To eliminate the divergence into the lung of both fields when planning an intact breast
treatment using isocentric medial and lateral opposed fields, it would be necessary to: -
answermatch the posterior diverging beam edges.
Physical penumbra width is defined as the lateral distance between which two isodose
curves at the level of dmax?
*physical penumbra = geometric & transmission penumbra, so lateral distance is wide -
answer20% and 80%
Two adjacent electron fields are to be used to treat a post-mastectomy chestwall. The
radiation oncologist has expressed concern that a cold spot at the surface be avoided.
Appropriate techniques include which of the following? - answerMove the junction
several times during the treatment course.
The minimum nominal distance a tissue compensator should be placed from the skin
surface without affecting the skin sparing effect is: - answer20.0 cm.
When treating with electrons typical X-ray contamination dose to a patient ranges from
approximately: - answer0.5% to 5%
Rounded ends on the leaves of a multi-leaf collimator are used to: - answerachieve a
constant penumbra as field size varies.
Which of the following statements regarding geometric penumbra is TRUE? -
answerThe penumbra increases as the distance from the source increases, all other
factors being equal.
, Which calculation method independently calculates the primary and the scattered
components of dose at a point in the calculation volume?
*calcs 2 components. 2 things can be "superimposed" on one another -
answerConvolution superposition
Which of the following statements is CORRECT regarding the concept of equivalent
squares in dose calculation? - answerA rectangular field is equivalent to a square field if
they have the same Area/Perimeter ratio.
Computerized MU calculations for delivery of the prescribed dose to a point near a
block need special care for which of the following reasons? - answerA steep dose
gradient exists near the block.
When an isocentric (SAD) technique is used in place of an SSD technique (both beams
treated at 100SSD) to deliver the same midpoint dose to a patient with two parallel
opposed fields, the: - answerratio of maximum dose to midpoint dose is increased
The number of atoms decaying per second is expressed in terms of their:
*as they decay, their "A" becomes lower than "Ao" - answeractivity.
Based on NCRP recommendations, which of the following is a guideline regarding
pregnancy and radiation exposure? - answerPregnant medical radiation workers can be
considered occupationally exposed individuals.
The dose response model applied in establishing dose limits for occupational workers is
the: - answerlinear no-threshold model.
Which of the following statements is/are TRUE concerning radiation warning signs? -
answerThe terms "Caution" or "Danger" may be used in "High Radiation Areas".
The installation of any new treatment planning system requires the acceptance testing
of which of the following? - answersoftware
At what frequency should treatment chart checks be accomplished for each patient? -
answerweekly
According to AAPM TG Report #142 standards, what is the minimum frequency for
checking the door interlock? - answerdaily
What is the standard file format for network communication that allows handling, storing,
transferring and printing of medical imaging data? - answerDICOM
The force that holds the nucleus together is: - answerstrong nuclear
