MDCB Practice Test 2023, 2020, 2018 Exam Questions and Answers Which one of the following DVH results for a pancreatic treatment plan of conventional fractionation meets QUANTEC recommended dose tolerances? - Correct Answers ✅25% of the stomach will receive 45Gy.Which of the following is TRUE regarding clinical electron beams? - Correct Answers ✅High 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? - Correct Answers ✅beam 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 - Correct Answers ✅Monte 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: - Correct Answers ✅helical LINAC 1 / 4
MDCB Practice Test 2023, 2020, 2018 Exam Questions and Answers Which of the following is the best thermal neutron absorber? - Correct Answers ✅boronated polyethylene Relative skin dose from a megavoltage photon beam is increased by which of the following? - Correct Answers ✅increasing the thickness bolus material used
The risk of symptomatic radiation pneumonitis is:
*more "symptoms" with chemo - Correct Answers ✅increased if certain chemotherapy agents are used.DVHs can confirm which of the following? - Correct Answers ✅The 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 - Correct Answers ✅higher / shorter What will result if a photon field abuts an electron field at the skin surface? - Correct Answers ✅photon side hot spot, electron side cold spot 2 / 4
MDCB Practice Test 2023, 2020, 2018 Exam Questions and Answers Isocentric, parallel opposed oblique fields with unequal
depths may result in: - Correct Answers ✅a 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? - Correct Answers ✅carbon fiber couch Which of the following processes best explains how a radiation beam is delivered during stepand-shoot IMRT? - Correct Answers ✅Radiation is only delivered while the MLC is stopped.Characteristics of MLC, in current medical LINACs, include
which of the following: - Correct Answers ✅"scalloped"
isodose curves in the penumbra region.Which of the following can be determined from the V20 obtained from a DVH for both lungs? - Correct Answers ✅volume 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: -
Correct Answers ✅match the posterior diverging beam edges. 3 / 4
MDCB Practice Test 2023, 2020, 2018 Exam Questions and Answers 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 - Correct Answers ✅20% 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? - Correct Answers ✅Move 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: - Correct Answers ✅20.0 cm.
When treating with electrons typical X-ray contamination
dose to a patient ranges from approximately: - Correct
Answers ✅0.5% to 5% Rounded ends on the leaves of a multi-leaf collimator are
used to: - Correct Answers ✅achieve a constant penumbra
as field size varies.
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