MDCB Exam Questions with 100 Verified

MDCB Exam Questions with 100% Verified Correct Answers Which one of the following dose volume histogram (DVH) results for a pancreatic treatment plan of conventional fractionation meets QUANTEC recommended dose tolerances?

• 75% of the left kidney will receive 30 Gy.
• 50% of the right kidney will receive 40 Gy.
• 50% of the liver will receive 42 Gy.
• 25% of the stomach will receive 45 Gy. - Correct Answer D. 25% of the stomach will receive 45 Gy.

An algorithm often used for electron beam dose calculations is:

• scatter-air ratio (SAR) summations.
• Batho & Young corrections.
• Clarkson calculations.
• pencil beams. - Correct Answer D. pencil beams.

Any error in the placement of adjacent fields during radiotherapy treatment is most likely to:

• be equally serious for beams of any penumbra.
• be more serious with beams of smaller penumbra.
• have no impact the treatment outcome.
• be more serious with beams of larger penumbra. - Correct Answer B. be more serious with beams

of smaller penumbra.A radiation oncology department has a selection of 6, 10, and 18 MV photon beams. For a 7 beam prostate Intensity Modulated Radiation Therapy (IMRT) plan, it would be appropriate to select a/an:

• 6 MV photon beam because it would deliver no neutron dose and the lowest doses to the tissue

outside the planning target volume (PTV).

• 6 MV photon beam because it would deliver some neutron dose, but give the best dose

distribution to the PTV.

• 10 MV photon beam because it would deliver a lower neutron dose than an 18 MV photon beam

and clinically acceptable doses to the bladder and rectum.

• 10 MV photon beam because it would deliver no neutron dose and the lowest doses to the tissue

outside the PTV. - Correct Answer A. 6 MV photon beam because it would deliver no neutron dose and the lowest doses to the tissue outside the planning target volume (PTV). 1 / 3

What can cause increased skin dose in IMRT for prostate cancer?

• prone position
• wedge under knees- a support device
• use of high energy photons
• carbon fiber couch - Correct Answer D. carbon fiber couch

Characteristics of multileaf collimators, in current medical LINACs, include which of the following:

• accommodates all field sizes.
• "scalloped" isodose curves in the penumbra region.
• ability to conform to all possible field shapes.
• inability to verify leaf shapes. - Correct Answer B. "scalloped" isodose curves in the penumbra

region.The minimum nominal distance a tissue compensator should be placed from the skin surface without

affecting the skin sparing effect is:

• 5.0 cm.
• 10.0 cm.
• 20.0 cm.
• 25.0 cm. - Correct Answer C. 20.0 cm.

When treating with electrons typical X-ray contamination dose to a patient ranges from

approximately:

• 0.1% to 0.4%
• 0.5% to 5%
• 6% to 9%
• 10% to 12% - Correct Answer B. 0.5% to 5%

The most significant factor effecting calculation of dose with tissue inhomogeneity correction is: (A) energy of the beam (B) size of inhomogeneity (C) depth of inhomogeneity - Correct Answer (B) size of inhomogeneity 2 / 3

The five year cure rate for a prostate cancer tumor treated with primary radiation is:

(A) 5 - 10%

(B) 25 - 30%

(C) 50 - 70%

(D) 75 - 95% - Correct Answer (D) 75 - 95% A lung tumor is to be treated utilizing a 90 degree arc. For a target volume centered 6.0 cm below the skin surface, how far below the skin surface should the isocenter be placed?(A) 2.5 cm (B) 6.0 cm (C) 9.0 cm (D) 12.0 cm - Correct Answer (C) 9.0 cm Very accurate specification of dose at depth in a wedged field necessitates that the medical dosimetrist accounts for which of the following factors?(A) same central axis percent depth dose that occurs in a wedged field (B) wedge transmission factor is measured in air or in tissue (C) no variations of the wedge transmission factor with field size (D) reduction in collimator scatter that is reaching the patient - Correct Answer (B) wedge transmission factor is measured in air or in tissue The five year cure rate for a bladder cancer tumor treated with primary radiation is:

(A) 0 - 5%

(B) 5 - 10%

(C) 25 - 30%

(D) 50 - 70% - Correct Answer (C) 25 - 30% The five-year survival rate for a esophageal cancer tumor treated with primary radiation is:

(A) 0 - 5%

(B) 5 - 10%

(C) 25 - 30%

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